2 Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010
3 Free Software Foundation, Inc.
4 This is part of the GNU Fortran manual.
5 For copying conditions, see the file gfortran.texi.
7 Permission is granted to copy, distribute and/or modify this document
8 under the terms of the GNU Free Documentation License, Version 1.3 or
9 any later version published by the Free Software Foundation; with the
10 Invariant Sections being ``Funding Free Software'', the Front-Cover
11 Texts being (a) (see below), and with the Back-Cover Texts being (b)
12 (see below). A copy of the license is included in the gfdl(7) man page.
15 Some basic guidelines for editing this document:
17 (1) The intrinsic procedures are to be listed in alphabetical order.
18 (2) The generic name is to be used.
19 (3) The specific names are included in the function index and in a
20 table at the end of the node (See ABS entry).
21 (4) Try to maintain the same style for each entry.
27 \gdef\acos{\mathop{\rm acos}\nolimits}
28 \gdef\asin{\mathop{\rm asin}\nolimits}
29 \gdef\atan{\mathop{\rm atan}\nolimits}
30 \gdef\acosh{\mathop{\rm acosh}\nolimits}
31 \gdef\asinh{\mathop{\rm asinh}\nolimits}
32 \gdef\atanh{\mathop{\rm atanh}\nolimits}
36 @node Intrinsic Procedures
37 @chapter Intrinsic Procedures
38 @cindex intrinsic procedures
41 * Introduction: Introduction to Intrinsics
42 * @code{ABORT}: ABORT, Abort the program
43 * @code{ABS}: ABS, Absolute value
44 * @code{ACCESS}: ACCESS, Checks file access modes
45 * @code{ACHAR}: ACHAR, Character in @acronym{ASCII} collating sequence
46 * @code{ACOS}: ACOS, Arccosine function
47 * @code{ACOSH}: ACOSH, Inverse hyperbolic cosine function
48 * @code{ADJUSTL}: ADJUSTL, Left adjust a string
49 * @code{ADJUSTR}: ADJUSTR, Right adjust a string
50 * @code{AIMAG}: AIMAG, Imaginary part of complex number
51 * @code{AINT}: AINT, Truncate to a whole number
52 * @code{ALARM}: ALARM, Set an alarm clock
53 * @code{ALL}: ALL, Determine if all values are true
54 * @code{ALLOCATED}: ALLOCATED, Status of allocatable entity
55 * @code{AND}: AND, Bitwise logical AND
56 * @code{ANINT}: ANINT, Nearest whole number
57 * @code{ANY}: ANY, Determine if any values are true
58 * @code{ASIN}: ASIN, Arcsine function
59 * @code{ASINH}: ASINH, Inverse hyperbolic sine function
60 * @code{ASSOCIATED}: ASSOCIATED, Status of a pointer or pointer/target pair
61 * @code{ATAN}: ATAN, Arctangent function
62 * @code{ATAN2}: ATAN2, Arctangent function
63 * @code{ATANH}: ATANH, Inverse hyperbolic tangent function
64 * @code{BESSEL_J0}: BESSEL_J0, Bessel function of the first kind of order 0
65 * @code{BESSEL_J1}: BESSEL_J1, Bessel function of the first kind of order 1
66 * @code{BESSEL_JN}: BESSEL_JN, Bessel function of the first kind
67 * @code{BESSEL_Y0}: BESSEL_Y0, Bessel function of the second kind of order 0
68 * @code{BESSEL_Y1}: BESSEL_Y1, Bessel function of the second kind of order 1
69 * @code{BESSEL_YN}: BESSEL_YN, Bessel function of the second kind
70 * @code{BGE}: BGE, Bitwise greater than or equal to
71 * @code{BGT}: BGT, Bitwise greater than
72 * @code{BIT_SIZE}: BIT_SIZE, Bit size inquiry function
73 * @code{BLE}: BLE, Bitwise less than or equal to
74 * @code{BLT}: BLT, Bitwise less than
75 * @code{BTEST}: BTEST, Bit test function
76 * @code{C_ASSOCIATED}: C_ASSOCIATED, Status of a C pointer
77 * @code{C_F_POINTER}: C_F_POINTER, Convert C into Fortran pointer
78 * @code{C_F_PROCPOINTER}: C_F_PROCPOINTER, Convert C into Fortran procedure pointer
79 * @code{C_FUNLOC}: C_FUNLOC, Obtain the C address of a procedure
80 * @code{C_LOC}: C_LOC, Obtain the C address of an object
81 * @code{C_SIZEOF}: C_SIZEOF, Size in bytes of an expression
82 * @code{CEILING}: CEILING, Integer ceiling function
83 * @code{CHAR}: CHAR, Integer-to-character conversion function
84 * @code{CHDIR}: CHDIR, Change working directory
85 * @code{CHMOD}: CHMOD, Change access permissions of files
86 * @code{CMPLX}: CMPLX, Complex conversion function
87 * @code{COMMAND_ARGUMENT_COUNT}: COMMAND_ARGUMENT_COUNT, Get number of command line arguments
88 * @code{COMPLEX}: COMPLEX, Complex conversion function
89 * @code{COMPILER_VERSION}: COMPILER_VERSION, Compiler version string
90 * @code{COMPILER_OPTIONS}: COMPILER_OPTIONS, Options passed to the compiler
91 * @code{CONJG}: CONJG, Complex conjugate function
92 * @code{COS}: COS, Cosine function
93 * @code{COSH}: COSH, Hyperbolic cosine function
94 * @code{COUNT}: COUNT, Count occurrences of TRUE in an array
95 * @code{CPU_TIME}: CPU_TIME, CPU time subroutine
96 * @code{CSHIFT}: CSHIFT, Circular shift elements of an array
97 * @code{CTIME}: CTIME, Subroutine (or function) to convert a time into a string
98 * @code{DATE_AND_TIME}: DATE_AND_TIME, Date and time subroutine
99 * @code{DBLE}: DBLE, Double precision conversion function
100 * @code{DCMPLX}: DCMPLX, Double complex conversion function
101 * @code{DIGITS}: DIGITS, Significant digits function
102 * @code{DIM}: DIM, Positive difference
103 * @code{DOT_PRODUCT}: DOT_PRODUCT, Dot product function
104 * @code{DPROD}: DPROD, Double product function
105 * @code{DREAL}: DREAL, Double real part function
106 * @code{DSHIFTL}: DSHIFTL, Combined left shift
107 * @code{DSHIFTR}: DSHIFTR, Combined right shift
108 * @code{DTIME}: DTIME, Execution time subroutine (or function)
109 * @code{EOSHIFT}: EOSHIFT, End-off shift elements of an array
110 * @code{EPSILON}: EPSILON, Epsilon function
111 * @code{ERF}: ERF, Error function
112 * @code{ERFC}: ERFC, Complementary error function
113 * @code{ERFC_SCALED}: ERFC_SCALED, Exponentially-scaled complementary error function
114 * @code{ETIME}: ETIME, Execution time subroutine (or function)
115 * @code{EXECUTE_COMMAND_LINE}: EXECUTE_COMMAND_LINE, Execute a shell command
116 * @code{EXIT}: EXIT, Exit the program with status.
117 * @code{EXP}: EXP, Exponential function
118 * @code{EXPONENT}: EXPONENT, Exponent function
119 * @code{EXTENDS_TYPE_OF}: EXTENDS_TYPE_OF, Query dynamic type for extension
120 * @code{FDATE}: FDATE, Subroutine (or function) to get the current time as a string
121 * @code{FGET}: FGET, Read a single character in stream mode from stdin
122 * @code{FGETC}: FGETC, Read a single character in stream mode
123 * @code{FLOOR}: FLOOR, Integer floor function
124 * @code{FLUSH}: FLUSH, Flush I/O unit(s)
125 * @code{FNUM}: FNUM, File number function
126 * @code{FPUT}: FPUT, Write a single character in stream mode to stdout
127 * @code{FPUTC}: FPUTC, Write a single character in stream mode
128 * @code{FRACTION}: FRACTION, Fractional part of the model representation
129 * @code{FREE}: FREE, Memory de-allocation subroutine
130 * @code{FSEEK}: FSEEK, Low level file positioning subroutine
131 * @code{FSTAT}: FSTAT, Get file status
132 * @code{FTELL}: FTELL, Current stream position
133 * @code{GAMMA}: GAMMA, Gamma function
134 * @code{GERROR}: GERROR, Get last system error message
135 * @code{GETARG}: GETARG, Get command line arguments
136 * @code{GET_COMMAND}: GET_COMMAND, Get the entire command line
137 * @code{GET_COMMAND_ARGUMENT}: GET_COMMAND_ARGUMENT, Get command line arguments
138 * @code{GETCWD}: GETCWD, Get current working directory
139 * @code{GETENV}: GETENV, Get an environmental variable
140 * @code{GET_ENVIRONMENT_VARIABLE}: GET_ENVIRONMENT_VARIABLE, Get an environmental variable
141 * @code{GETGID}: GETGID, Group ID function
142 * @code{GETLOG}: GETLOG, Get login name
143 * @code{GETPID}: GETPID, Process ID function
144 * @code{GETUID}: GETUID, User ID function
145 * @code{GMTIME}: GMTIME, Convert time to GMT info
146 * @code{HOSTNM}: HOSTNM, Get system host name
147 * @code{HUGE}: HUGE, Largest number of a kind
148 * @code{HYPOT}: HYPOT, Euclidean distance function
149 * @code{IACHAR}: IACHAR, Code in @acronym{ASCII} collating sequence
150 * @code{IALL}: IALL, Bitwise AND of array elements
151 * @code{IAND}: IAND, Bitwise logical and
152 * @code{IANY}: IANY, Bitwise OR of array elements
153 * @code{IARGC}: IARGC, Get the number of command line arguments
154 * @code{IBCLR}: IBCLR, Clear bit
155 * @code{IBITS}: IBITS, Bit extraction
156 * @code{IBSET}: IBSET, Set bit
157 * @code{ICHAR}: ICHAR, Character-to-integer conversion function
158 * @code{IDATE}: IDATE, Current local time (day/month/year)
159 * @code{IEOR}: IEOR, Bitwise logical exclusive or
160 * @code{IERRNO}: IERRNO, Function to get the last system error number
161 * @code{IMAGE_INDEX}: IMAGE_INDEX, Cosubscript to image index conversion
162 * @code{INDEX}: INDEX intrinsic, Position of a substring within a string
163 * @code{INT}: INT, Convert to integer type
164 * @code{INT2}: INT2, Convert to 16-bit integer type
165 * @code{INT8}: INT8, Convert to 64-bit integer type
166 * @code{IOR}: IOR, Bitwise logical or
167 * @code{IPARITY}: IPARITY, Bitwise XOR of array elements
168 * @code{IRAND}: IRAND, Integer pseudo-random number
169 * @code{IS_IOSTAT_END}: IS_IOSTAT_END, Test for end-of-file value
170 * @code{IS_IOSTAT_EOR}: IS_IOSTAT_EOR, Test for end-of-record value
171 * @code{ISATTY}: ISATTY, Whether a unit is a terminal device
172 * @code{ISHFT}: ISHFT, Shift bits
173 * @code{ISHFTC}: ISHFTC, Shift bits circularly
174 * @code{ISNAN}: ISNAN, Tests for a NaN
175 * @code{ITIME}: ITIME, Current local time (hour/minutes/seconds)
176 * @code{KILL}: KILL, Send a signal to a process
177 * @code{KIND}: KIND, Kind of an entity
178 * @code{LBOUND}: LBOUND, Lower dimension bounds of an array
179 * @code{LCOBOUND}: LCOBOUND, Lower codimension bounds of an array
180 * @code{LEADZ}: LEADZ, Number of leading zero bits of an integer
181 * @code{LEN}: LEN, Length of a character entity
182 * @code{LEN_TRIM}: LEN_TRIM, Length of a character entity without trailing blank characters
183 * @code{LGE}: LGE, Lexical greater than or equal
184 * @code{LGT}: LGT, Lexical greater than
185 * @code{LINK}: LINK, Create a hard link
186 * @code{LLE}: LLE, Lexical less than or equal
187 * @code{LLT}: LLT, Lexical less than
188 * @code{LNBLNK}: LNBLNK, Index of the last non-blank character in a string
189 * @code{LOC}: LOC, Returns the address of a variable
190 * @code{LOG}: LOG, Logarithm function
191 * @code{LOG10}: LOG10, Base 10 logarithm function
192 * @code{LOG_GAMMA}: LOG_GAMMA, Logarithm of the Gamma function
193 * @code{LOGICAL}: LOGICAL, Convert to logical type
194 * @code{LONG}: LONG, Convert to integer type
195 * @code{LSHIFT}: LSHIFT, Left shift bits
196 * @code{LSTAT}: LSTAT, Get file status
197 * @code{LTIME}: LTIME, Convert time to local time info
198 * @code{MALLOC}: MALLOC, Dynamic memory allocation function
199 * @code{MASKL}: MASKL, Left justified mask
200 * @code{MASKR}: MASKR, Right justified mask
201 * @code{MATMUL}: MATMUL, matrix multiplication
202 * @code{MAX}: MAX, Maximum value of an argument list
203 * @code{MAXEXPONENT}: MAXEXPONENT, Maximum exponent of a real kind
204 * @code{MAXLOC}: MAXLOC, Location of the maximum value within an array
205 * @code{MAXVAL}: MAXVAL, Maximum value of an array
206 * @code{MCLOCK}: MCLOCK, Time function
207 * @code{MCLOCK8}: MCLOCK8, Time function (64-bit)
208 * @code{MERGE}: MERGE, Merge arrays
209 * @code{MERGE_BITS}: MERGE_BITS, Merge of bits under mask
210 * @code{MIN}: MIN, Minimum value of an argument list
211 * @code{MINEXPONENT}: MINEXPONENT, Minimum exponent of a real kind
212 * @code{MINLOC}: MINLOC, Location of the minimum value within an array
213 * @code{MINVAL}: MINVAL, Minimum value of an array
214 * @code{MOD}: MOD, Remainder function
215 * @code{MODULO}: MODULO, Modulo function
216 * @code{MOVE_ALLOC}: MOVE_ALLOC, Move allocation from one object to another
217 * @code{MVBITS}: MVBITS, Move bits from one integer to another
218 * @code{NEAREST}: NEAREST, Nearest representable number
219 * @code{NEW_LINE}: NEW_LINE, New line character
220 * @code{NINT}: NINT, Nearest whole number
221 * @code{NORM2}: NORM2, Euclidean vector norm
222 * @code{NOT}: NOT, Logical negation
223 * @code{NULL}: NULL, Function that returns an disassociated pointer
224 * @code{NUM_IMAGES}: NUM_IMAGES, Number of images
225 * @code{OR}: OR, Bitwise logical OR
226 * @code{PACK}: PACK, Pack an array into an array of rank one
227 * @code{PARITY}: PARITY, Reduction with exclusive OR
228 * @code{PERROR}: PERROR, Print system error message
229 * @code{POPCNT}: POPCNT, Number of bits set
230 * @code{POPPAR}: POPPAR, Parity of the number of bits set
231 * @code{PRECISION}: PRECISION, Decimal precision of a real kind
232 * @code{PRESENT}: PRESENT, Determine whether an optional dummy argument is specified
233 * @code{PRODUCT}: PRODUCT, Product of array elements
234 * @code{RADIX}: RADIX, Base of a data model
235 * @code{RANDOM_NUMBER}: RANDOM_NUMBER, Pseudo-random number
236 * @code{RANDOM_SEED}: RANDOM_SEED, Initialize a pseudo-random number sequence
237 * @code{RAND}: RAND, Real pseudo-random number
238 * @code{RANGE}: RANGE, Decimal exponent range
239 * @code{RAN}: RAN, Real pseudo-random number
240 * @code{REAL}: REAL, Convert to real type
241 * @code{RENAME}: RENAME, Rename a file
242 * @code{REPEAT}: REPEAT, Repeated string concatenation
243 * @code{RESHAPE}: RESHAPE, Function to reshape an array
244 * @code{RRSPACING}: RRSPACING, Reciprocal of the relative spacing
245 * @code{RSHIFT}: RSHIFT, Right shift bits
246 * @code{SAME_TYPE_AS}: SAME_TYPE_AS, Query dynamic types for equality
247 * @code{SCALE}: SCALE, Scale a real value
248 * @code{SCAN}: SCAN, Scan a string for the presence of a set of characters
249 * @code{SECNDS}: SECNDS, Time function
250 * @code{SECOND}: SECOND, CPU time function
251 * @code{SELECTED_CHAR_KIND}: SELECTED_CHAR_KIND, Choose character kind
252 * @code{SELECTED_INT_KIND}: SELECTED_INT_KIND, Choose integer kind
253 * @code{SELECTED_REAL_KIND}: SELECTED_REAL_KIND, Choose real kind
254 * @code{SET_EXPONENT}: SET_EXPONENT, Set the exponent of the model
255 * @code{SHAPE}: SHAPE, Determine the shape of an array
256 * @code{SHIFTA}: SHIFTA, Right shift with fill
257 * @code{SHIFTL}: SHIFTL, Left shift
258 * @code{SHIFTR}: SHIFTR, Right shift
259 * @code{SIGN}: SIGN, Sign copying function
260 * @code{SIGNAL}: SIGNAL, Signal handling subroutine (or function)
261 * @code{SIN}: SIN, Sine function
262 * @code{SINH}: SINH, Hyperbolic sine function
263 * @code{SIZE}: SIZE, Function to determine the size of an array
264 * @code{SIZEOF}: SIZEOF, Determine the size in bytes of an expression
265 * @code{SLEEP}: SLEEP, Sleep for the specified number of seconds
266 * @code{SPACING}: SPACING, Smallest distance between two numbers of a given type
267 * @code{SPREAD}: SPREAD, Add a dimension to an array
268 * @code{SQRT}: SQRT, Square-root function
269 * @code{SRAND}: SRAND, Reinitialize the random number generator
270 * @code{STAT}: STAT, Get file status
271 * @code{STORAGE_SIZE}: STORAGE_SIZE, Storage size in bits
272 * @code{SUM}: SUM, Sum of array elements
273 * @code{SYMLNK}: SYMLNK, Create a symbolic link
274 * @code{SYSTEM}: SYSTEM, Execute a shell command
275 * @code{SYSTEM_CLOCK}: SYSTEM_CLOCK, Time function
276 * @code{TAN}: TAN, Tangent function
277 * @code{TANH}: TANH, Hyperbolic tangent function
278 * @code{THIS_IMAGE}: THIS_IMAGE, Cosubscript index of this image
279 * @code{TIME}: TIME, Time function
280 * @code{TIME8}: TIME8, Time function (64-bit)
281 * @code{TINY}: TINY, Smallest positive number of a real kind
282 * @code{TRAILZ}: TRAILZ, Number of trailing zero bits of an integer
283 * @code{TRANSFER}: TRANSFER, Transfer bit patterns
284 * @code{TRANSPOSE}: TRANSPOSE, Transpose an array of rank two
285 * @code{TRIM}: TRIM, Remove trailing blank characters of a string
286 * @code{TTYNAM}: TTYNAM, Get the name of a terminal device.
287 * @code{UBOUND}: UBOUND, Upper dimension bounds of an array
288 * @code{UCOBOUND}: UCOBOUND, Upper codimension bounds of an array
289 * @code{UMASK}: UMASK, Set the file creation mask
290 * @code{UNLINK}: UNLINK, Remove a file from the file system
291 * @code{UNPACK}: UNPACK, Unpack an array of rank one into an array
292 * @code{VERIFY}: VERIFY, Scan a string for the absence of a set of characters
293 * @code{XOR}: XOR, Bitwise logical exclusive or
296 @node Introduction to Intrinsics
297 @section Introduction to intrinsic procedures
299 The intrinsic procedures provided by GNU Fortran include all of the
300 intrinsic procedures required by the Fortran 95 standard, a set of
301 intrinsic procedures for backwards compatibility with G77, and a
302 selection of intrinsic procedures from the Fortran 2003 and Fortran 2008
303 standards. Any conflict between a description here and a description in
304 either the Fortran 95 standard, the Fortran 2003 standard or the Fortran
305 2008 standard is unintentional, and the standard(s) should be considered
308 The enumeration of the @code{KIND} type parameter is processor defined in
309 the Fortran 95 standard. GNU Fortran defines the default integer type and
310 default real type by @code{INTEGER(KIND=4)} and @code{REAL(KIND=4)},
311 respectively. The standard mandates that both data types shall have
312 another kind, which have more precision. On typical target architectures
313 supported by @command{gfortran}, this kind type parameter is @code{KIND=8}.
314 Hence, @code{REAL(KIND=8)} and @code{DOUBLE PRECISION} are equivalent.
315 In the description of generic intrinsic procedures, the kind type parameter
316 will be specified by @code{KIND=*}, and in the description of specific
317 names for an intrinsic procedure the kind type parameter will be explicitly
318 given (e.g., @code{REAL(KIND=4)} or @code{REAL(KIND=8)}). Finally, for
319 brevity the optional @code{KIND=} syntax will be omitted.
321 Many of the intrinsic procedures take one or more optional arguments.
322 This document follows the convention used in the Fortran 95 standard,
323 and denotes such arguments by square brackets.
325 GNU Fortran offers the @option{-std=f95} and @option{-std=gnu} options,
326 which can be used to restrict the set of intrinsic procedures to a
327 given standard. By default, @command{gfortran} sets the @option{-std=gnu}
328 option, and so all intrinsic procedures described here are accepted. There
329 is one caveat. For a select group of intrinsic procedures, @command{g77}
330 implemented both a function and a subroutine. Both classes
331 have been implemented in @command{gfortran} for backwards compatibility
332 with @command{g77}. It is noted here that these functions and subroutines
333 cannot be intermixed in a given subprogram. In the descriptions that follow,
334 the applicable standard for each intrinsic procedure is noted.
339 @section @code{ABORT} --- Abort the program
341 @cindex program termination, with core dump
342 @cindex terminate program, with core dump
346 @item @emph{Description}:
347 @code{ABORT} causes immediate termination of the program. On operating
348 systems that support a core dump, @code{ABORT} will produce a core dump even if
349 the option @option{-fno-dump-core} is in effect, which is suitable for debugging
351 @c TODO: Check if this (with -fno-dump-core) is correct.
353 @item @emph{Standard}:
362 @item @emph{Return value}:
365 @item @emph{Example}:
368 integer :: i = 1, j = 2
369 if (i /= j) call abort
370 end program test_abort
373 @item @emph{See also}:
374 @ref{EXIT}, @ref{KILL}
381 @section @code{ABS} --- Absolute value
388 @cindex absolute value
391 @item @emph{Description}:
392 @code{ABS(A)} computes the absolute value of @code{A}.
394 @item @emph{Standard}:
395 Fortran 77 and later, has overloads that are GNU extensions
401 @code{RESULT = ABS(A)}
403 @item @emph{Arguments}:
404 @multitable @columnfractions .15 .70
405 @item @var{A} @tab The type of the argument shall be an @code{INTEGER},
406 @code{REAL}, or @code{COMPLEX}.
409 @item @emph{Return value}:
410 The return value is of the same type and
411 kind as the argument except the return value is @code{REAL} for a
412 @code{COMPLEX} argument.
414 @item @emph{Example}:
419 complex :: z = (-1.e0,0.e0)
426 @item @emph{Specific names}:
427 @multitable @columnfractions .20 .20 .20 .25
428 @item Name @tab Argument @tab Return type @tab Standard
429 @item @code{ABS(A)} @tab @code{REAL(4) A} @tab @code{REAL(4)} @tab Fortran 77 and later
430 @item @code{CABS(A)} @tab @code{COMPLEX(4) A} @tab @code{REAL(4)} @tab Fortran 77 and later
431 @item @code{DABS(A)} @tab @code{REAL(8) A} @tab @code{REAL(8)} @tab Fortran 77 and later
432 @item @code{IABS(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab Fortran 77 and later
433 @item @code{ZABS(A)} @tab @code{COMPLEX(8) A} @tab @code{COMPLEX(8)} @tab GNU extension
434 @item @code{CDABS(A)} @tab @code{COMPLEX(8) A} @tab @code{COMPLEX(8)} @tab GNU extension
441 @section @code{ACCESS} --- Checks file access modes
443 @cindex file system, access mode
446 @item @emph{Description}:
447 @code{ACCESS(NAME, MODE)} checks whether the file @var{NAME}
448 exists, is readable, writable or executable. Except for the
449 executable check, @code{ACCESS} can be replaced by
450 Fortran 95's @code{INQUIRE}.
452 @item @emph{Standard}:
459 @code{RESULT = ACCESS(NAME, MODE)}
461 @item @emph{Arguments}:
462 @multitable @columnfractions .15 .70
463 @item @var{NAME} @tab Scalar @code{CHARACTER} of default kind with the
464 file name. Tailing blank are ignored unless the character @code{achar(0)}
465 is present, then all characters up to and excluding @code{achar(0)} are
467 @item @var{MODE} @tab Scalar @code{CHARACTER} of default kind with the
468 file access mode, may be any concatenation of @code{"r"} (readable),
469 @code{"w"} (writable) and @code{"x"} (executable), or @code{" "} to check
473 @item @emph{Return value}:
474 Returns a scalar @code{INTEGER}, which is @code{0} if the file is
475 accessible in the given mode; otherwise or if an invalid argument
476 has been given for @code{MODE} the value @code{1} is returned.
478 @item @emph{Example}:
482 character(len=*), parameter :: file = 'test.dat'
483 character(len=*), parameter :: file2 = 'test.dat '//achar(0)
484 if(access(file,' ') == 0) print *, trim(file),' is exists'
485 if(access(file,'r') == 0) print *, trim(file),' is readable'
486 if(access(file,'w') == 0) print *, trim(file),' is writable'
487 if(access(file,'x') == 0) print *, trim(file),' is executable'
488 if(access(file2,'rwx') == 0) &
489 print *, trim(file2),' is readable, writable and executable'
490 end program access_test
492 @item @emph{Specific names}:
493 @item @emph{See also}:
500 @section @code{ACHAR} --- Character in @acronym{ASCII} collating sequence
502 @cindex @acronym{ASCII} collating sequence
503 @cindex collating sequence, @acronym{ASCII}
506 @item @emph{Description}:
507 @code{ACHAR(I)} returns the character located at position @code{I}
508 in the @acronym{ASCII} collating sequence.
510 @item @emph{Standard}:
511 Fortran 77 and later, with @var{KIND} argument Fortran 2003 and later
517 @code{RESULT = ACHAR(I [, KIND])}
519 @item @emph{Arguments}:
520 @multitable @columnfractions .15 .70
521 @item @var{I} @tab The type shall be @code{INTEGER}.
522 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
523 expression indicating the kind parameter of the result.
526 @item @emph{Return value}:
527 The return value is of type @code{CHARACTER} with a length of one.
528 If the @var{KIND} argument is present, the return value is of the
529 specified kind and of the default kind otherwise.
531 @item @emph{Example}:
536 end program test_achar
540 See @ref{ICHAR} for a discussion of converting between numerical values
541 and formatted string representations.
543 @item @emph{See also}:
544 @ref{CHAR}, @ref{IACHAR}, @ref{ICHAR}
551 @section @code{ACOS} --- Arccosine function
554 @cindex trigonometric function, cosine, inverse
555 @cindex cosine, inverse
558 @item @emph{Description}:
559 @code{ACOS(X)} computes the arccosine of @var{X} (inverse of @code{COS(X)}).
561 @item @emph{Standard}:
562 Fortran 77 and later, for a complex argument Fortran 2008 or later
568 @code{RESULT = ACOS(X)}
570 @item @emph{Arguments}:
571 @multitable @columnfractions .15 .70
572 @item @var{X} @tab The type shall either be @code{REAL} with a magnitude that is
573 less than or equal to one - or the type shall be @code{COMPLEX}.
576 @item @emph{Return value}:
577 The return value is of the same type and kind as @var{X}.
578 The real part of the result is in radians and lies in the range
579 @math{0 \leq \Re \acos(x) \leq \pi}.
581 @item @emph{Example}:
584 real(8) :: x = 0.866_8
586 end program test_acos
589 @item @emph{Specific names}:
590 @multitable @columnfractions .20 .20 .20 .25
591 @item Name @tab Argument @tab Return type @tab Standard
592 @item @code{ACOS(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 77 and later
593 @item @code{DACOS(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 77 and later
596 @item @emph{See also}:
597 Inverse function: @ref{COS}
604 @section @code{ACOSH} --- Inverse hyperbolic cosine function
607 @cindex area hyperbolic cosine
608 @cindex inverse hyperbolic cosine
609 @cindex hyperbolic function, cosine, inverse
610 @cindex cosine, hyperbolic, inverse
613 @item @emph{Description}:
614 @code{ACOSH(X)} computes the inverse hyperbolic cosine of @var{X}.
616 @item @emph{Standard}:
617 Fortran 2008 and later
623 @code{RESULT = ACOSH(X)}
625 @item @emph{Arguments}:
626 @multitable @columnfractions .15 .70
627 @item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
630 @item @emph{Return value}:
631 The return value has the same type and kind as @var{X}. If @var{X} is
632 complex, the imaginary part of the result is in radians and lies between
633 @math{ 0 \leq \Im \acosh(x) \leq \pi}.
635 @item @emph{Example}:
638 REAL(8), DIMENSION(3) :: x = (/ 1.0, 2.0, 3.0 /)
643 @item @emph{Specific names}:
644 @multitable @columnfractions .20 .20 .20 .25
645 @item Name @tab Argument @tab Return type @tab Standard
646 @item @code{DACOSH(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU extension
649 @item @emph{See also}:
650 Inverse function: @ref{COSH}
656 @section @code{ADJUSTL} --- Left adjust a string
658 @cindex string, adjust left
659 @cindex adjust string
662 @item @emph{Description}:
663 @code{ADJUSTL(STRING)} will left adjust a string by removing leading spaces.
664 Spaces are inserted at the end of the string as needed.
666 @item @emph{Standard}:
673 @code{RESULT = ADJUSTL(STRING)}
675 @item @emph{Arguments}:
676 @multitable @columnfractions .15 .70
677 @item @var{STRING} @tab The type shall be @code{CHARACTER}.
680 @item @emph{Return value}:
681 The return value is of type @code{CHARACTER} and of the same kind as
682 @var{STRING} where leading spaces are removed and the same number of
683 spaces are inserted on the end of @var{STRING}.
685 @item @emph{Example}:
688 character(len=20) :: str = ' gfortran'
691 end program test_adjustl
694 @item @emph{See also}:
695 @ref{ADJUSTR}, @ref{TRIM}
701 @section @code{ADJUSTR} --- Right adjust a string
703 @cindex string, adjust right
704 @cindex adjust string
707 @item @emph{Description}:
708 @code{ADJUSTR(STRING)} will right adjust a string by removing trailing spaces.
709 Spaces are inserted at the start of the string as needed.
711 @item @emph{Standard}:
718 @code{RESULT = ADJUSTR(STRING)}
720 @item @emph{Arguments}:
721 @multitable @columnfractions .15 .70
722 @item @var{STR} @tab The type shall be @code{CHARACTER}.
725 @item @emph{Return value}:
726 The return value is of type @code{CHARACTER} and of the same kind as
727 @var{STRING} where trailing spaces are removed and the same number of
728 spaces are inserted at the start of @var{STRING}.
730 @item @emph{Example}:
733 character(len=20) :: str = 'gfortran'
736 end program test_adjustr
739 @item @emph{See also}:
740 @ref{ADJUSTL}, @ref{TRIM}
746 @section @code{AIMAG} --- Imaginary part of complex number
751 @cindex complex numbers, imaginary part
754 @item @emph{Description}:
755 @code{AIMAG(Z)} yields the imaginary part of complex argument @code{Z}.
756 The @code{IMAG(Z)} and @code{IMAGPART(Z)} intrinsic functions are provided
757 for compatibility with @command{g77}, and their use in new code is
758 strongly discouraged.
760 @item @emph{Standard}:
761 Fortran 77 and later, has overloads that are GNU extensions
767 @code{RESULT = AIMAG(Z)}
769 @item @emph{Arguments}:
770 @multitable @columnfractions .15 .70
771 @item @var{Z} @tab The type of the argument shall be @code{COMPLEX}.
774 @item @emph{Return value}:
775 The return value is of type @code{REAL} with the
776 kind type parameter of the argument.
778 @item @emph{Example}:
783 z4 = cmplx(1.e0_4, 0.e0_4)
784 z8 = cmplx(0.e0_8, 1.e0_8)
785 print *, aimag(z4), dimag(z8)
786 end program test_aimag
789 @item @emph{Specific names}:
790 @multitable @columnfractions .20 .20 .20 .25
791 @item Name @tab Argument @tab Return type @tab Standard
792 @item @code{AIMAG(Z)} @tab @code{COMPLEX Z} @tab @code{REAL} @tab GNU extension
793 @item @code{DIMAG(Z)} @tab @code{COMPLEX(8) Z} @tab @code{REAL(8)} @tab GNU extension
794 @item @code{IMAG(Z)} @tab @code{COMPLEX Z} @tab @code{REAL} @tab GNU extension
795 @item @code{IMAGPART(Z)} @tab @code{COMPLEX Z} @tab @code{REAL} @tab GNU extension
802 @section @code{AINT} --- Truncate to a whole number
806 @cindex rounding, floor
809 @item @emph{Description}:
810 @code{AINT(A [, KIND])} truncates its argument to a whole number.
812 @item @emph{Standard}:
819 @code{RESULT = AINT(A [, KIND])}
821 @item @emph{Arguments}:
822 @multitable @columnfractions .15 .70
823 @item @var{A} @tab The type of the argument shall be @code{REAL}.
824 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
825 expression indicating the kind parameter of the result.
828 @item @emph{Return value}:
829 The return value is of type @code{REAL} with the kind type parameter of the
830 argument if the optional @var{KIND} is absent; otherwise, the kind
831 type parameter will be given by @var{KIND}. If the magnitude of
832 @var{X} is less than one, @code{AINT(X)} returns zero. If the
833 magnitude is equal to or greater than one then it returns the largest
834 whole number that does not exceed its magnitude. The sign is the same
835 as the sign of @var{X}.
837 @item @emph{Example}:
844 print *, aint(x4), dint(x8)
846 end program test_aint
849 @item @emph{Specific names}:
850 @multitable @columnfractions .20 .20 .20 .25
851 @item Name @tab Argument @tab Return type @tab Standard
852 @item @code{AINT(A)} @tab @code{REAL(4) A} @tab @code{REAL(4)} @tab Fortran 77 and later
853 @item @code{DINT(A)} @tab @code{REAL(8) A} @tab @code{REAL(8)} @tab Fortran 77 and later
860 @section @code{ALARM} --- Execute a routine after a given delay
862 @cindex delayed execution
865 @item @emph{Description}:
866 @code{ALARM(SECONDS, HANDLER [, STATUS])} causes external subroutine @var{HANDLER}
867 to be executed after a delay of @var{SECONDS} by using @code{alarm(2)} to
868 set up a signal and @code{signal(2)} to catch it. If @var{STATUS} is
869 supplied, it will be returned with the number of seconds remaining until
870 any previously scheduled alarm was due to be delivered, or zero if there
871 was no previously scheduled alarm.
873 @item @emph{Standard}:
880 @code{CALL ALARM(SECONDS, HANDLER [, STATUS])}
882 @item @emph{Arguments}:
883 @multitable @columnfractions .15 .70
884 @item @var{SECONDS} @tab The type of the argument shall be a scalar
885 @code{INTEGER}. It is @code{INTENT(IN)}.
886 @item @var{HANDLER} @tab Signal handler (@code{INTEGER FUNCTION} or
887 @code{SUBROUTINE}) or dummy/global @code{INTEGER} scalar. The scalar
888 values may be either @code{SIG_IGN=1} to ignore the alarm generated
889 or @code{SIG_DFL=0} to set the default action. It is @code{INTENT(IN)}.
890 @item @var{STATUS} @tab (Optional) @var{STATUS} shall be a scalar
891 variable of the default @code{INTEGER} kind. It is @code{INTENT(OUT)}.
894 @item @emph{Example}:
897 external handler_print
899 call alarm (3, handler_print, i)
902 end program test_alarm
904 This will cause the external routine @var{handler_print} to be called
911 @section @code{ALL} --- All values in @var{MASK} along @var{DIM} are true
913 @cindex array, apply condition
914 @cindex array, condition testing
917 @item @emph{Description}:
918 @code{ALL(MASK [, DIM])} determines if all the values are true in @var{MASK}
919 in the array along dimension @var{DIM}.
921 @item @emph{Standard}:
925 Transformational function
928 @code{RESULT = ALL(MASK [, DIM])}
930 @item @emph{Arguments}:
931 @multitable @columnfractions .15 .70
932 @item @var{MASK} @tab The type of the argument shall be @code{LOGICAL} and
933 it shall not be scalar.
934 @item @var{DIM} @tab (Optional) @var{DIM} shall be a scalar integer
935 with a value that lies between one and the rank of @var{MASK}.
938 @item @emph{Return value}:
939 @code{ALL(MASK)} returns a scalar value of type @code{LOGICAL} where
940 the kind type parameter is the same as the kind type parameter of
941 @var{MASK}. If @var{DIM} is present, then @code{ALL(MASK, DIM)} returns
942 an array with the rank of @var{MASK} minus 1. The shape is determined from
943 the shape of @var{MASK} where the @var{DIM} dimension is elided.
947 @code{ALL(MASK)} is true if all elements of @var{MASK} are true.
948 It also is true if @var{MASK} has zero size; otherwise, it is false.
950 If the rank of @var{MASK} is one, then @code{ALL(MASK,DIM)} is equivalent
951 to @code{ALL(MASK)}. If the rank is greater than one, then @code{ALL(MASK,DIM)}
952 is determined by applying @code{ALL} to the array sections.
955 @item @emph{Example}:
959 l = all((/.true., .true., .true./))
964 integer a(2,3), b(2,3)
968 print *, all(a .eq. b, 1)
969 print *, all(a .eq. b, 2)
970 end subroutine section
978 @section @code{ALLOCATED} --- Status of an allocatable entity
980 @cindex allocation, status
983 @item @emph{Description}:
984 @code{ALLOCATED(ARRAY)} and @code{ALLOCATED(SCALAR)} check the allocation
985 status of @var{ARRAY} and @var{SCALAR}, respectively.
987 @item @emph{Standard}:
988 Fortran 95 and later. Note, the @code{SCALAR=} keyword and allocatable
989 scalar entities are available in Fortran 2003 and later.
995 @code{RESULT = ALLOCATED(ARRAY)} or @code{RESULT = ALLOCATED(SCALAR)}
997 @item @emph{Arguments}:
998 @multitable @columnfractions .15 .70
999 @item @var{ARRAY} @tab The argument shall be an @code{ALLOCATABLE} array.
1000 @item @var{SCALAR} @tab The argument shall be an @code{ALLOCATABLE} scalar.
1003 @item @emph{Return value}:
1004 The return value is a scalar @code{LOGICAL} with the default logical
1005 kind type parameter. If the argument is allocated, then the result is
1006 @code{.TRUE.}; otherwise, it returns @code{.FALSE.}
1008 @item @emph{Example}:
1010 program test_allocated
1012 real(4), allocatable :: x(:)
1013 if (.not. allocated(x)) allocate(x(i))
1014 end program test_allocated
1021 @section @code{AND} --- Bitwise logical AND
1023 @cindex bitwise logical and
1024 @cindex logical and, bitwise
1027 @item @emph{Description}:
1028 Bitwise logical @code{AND}.
1030 This intrinsic routine is provided for backwards compatibility with
1031 GNU Fortran 77. For integer arguments, programmers should consider
1032 the use of the @ref{IAND} intrinsic defined by the Fortran standard.
1034 @item @emph{Standard}:
1040 @item @emph{Syntax}:
1041 @code{RESULT = AND(I, J)}
1043 @item @emph{Arguments}:
1044 @multitable @columnfractions .15 .70
1045 @item @var{I} @tab The type shall be either a scalar @code{INTEGER}
1046 type or a scalar @code{LOGICAL} type.
1047 @item @var{J} @tab The type shall be the same as the type of @var{I}.
1050 @item @emph{Return value}:
1051 The return type is either a scalar @code{INTEGER} or a scalar
1052 @code{LOGICAL}. If the kind type parameters differ, then the
1053 smaller kind type is implicitly converted to larger kind, and the
1054 return has the larger kind.
1056 @item @emph{Example}:
1059 LOGICAL :: T = .TRUE., F = .FALSE.
1061 DATA a / Z'F' /, b / Z'3' /
1063 WRITE (*,*) AND(T, T), AND(T, F), AND(F, T), AND(F, F)
1064 WRITE (*,*) AND(a, b)
1068 @item @emph{See also}:
1069 Fortran 95 elemental function: @ref{IAND}
1075 @section @code{ANINT} --- Nearest whole number
1079 @cindex rounding, ceiling
1082 @item @emph{Description}:
1083 @code{ANINT(A [, KIND])} rounds its argument to the nearest whole number.
1085 @item @emph{Standard}:
1086 Fortran 77 and later
1091 @item @emph{Syntax}:
1092 @code{RESULT = ANINT(A [, KIND])}
1094 @item @emph{Arguments}:
1095 @multitable @columnfractions .15 .70
1096 @item @var{A} @tab The type of the argument shall be @code{REAL}.
1097 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
1098 expression indicating the kind parameter of the result.
1101 @item @emph{Return value}:
1102 The return value is of type real with the kind type parameter of the
1103 argument if the optional @var{KIND} is absent; otherwise, the kind
1104 type parameter will be given by @var{KIND}. If @var{A} is greater than
1105 zero, @code{ANINT(A)} returns @code{AINT(X+0.5)}. If @var{A} is
1106 less than or equal to zero then it returns @code{AINT(X-0.5)}.
1108 @item @emph{Example}:
1115 print *, anint(x4), dnint(x8)
1117 end program test_anint
1120 @item @emph{Specific names}:
1121 @multitable @columnfractions .20 .20 .20 .25
1122 @item Name @tab Argument @tab Return type @tab Standard
1123 @item @code{AINT(A)} @tab @code{REAL(4) A} @tab @code{REAL(4)} @tab Fortran 77 and later
1124 @item @code{DNINT(A)} @tab @code{REAL(8) A} @tab @code{REAL(8)} @tab Fortran 77 and later
1131 @section @code{ANY} --- Any value in @var{MASK} along @var{DIM} is true
1133 @cindex array, apply condition
1134 @cindex array, condition testing
1137 @item @emph{Description}:
1138 @code{ANY(MASK [, DIM])} determines if any of the values in the logical array
1139 @var{MASK} along dimension @var{DIM} are @code{.TRUE.}.
1141 @item @emph{Standard}:
1142 Fortran 95 and later
1145 Transformational function
1147 @item @emph{Syntax}:
1148 @code{RESULT = ANY(MASK [, DIM])}
1150 @item @emph{Arguments}:
1151 @multitable @columnfractions .15 .70
1152 @item @var{MASK} @tab The type of the argument shall be @code{LOGICAL} and
1153 it shall not be scalar.
1154 @item @var{DIM} @tab (Optional) @var{DIM} shall be a scalar integer
1155 with a value that lies between one and the rank of @var{MASK}.
1158 @item @emph{Return value}:
1159 @code{ANY(MASK)} returns a scalar value of type @code{LOGICAL} where
1160 the kind type parameter is the same as the kind type parameter of
1161 @var{MASK}. If @var{DIM} is present, then @code{ANY(MASK, DIM)} returns
1162 an array with the rank of @var{MASK} minus 1. The shape is determined from
1163 the shape of @var{MASK} where the @var{DIM} dimension is elided.
1167 @code{ANY(MASK)} is true if any element of @var{MASK} is true;
1168 otherwise, it is false. It also is false if @var{MASK} has zero size.
1170 If the rank of @var{MASK} is one, then @code{ANY(MASK,DIM)} is equivalent
1171 to @code{ANY(MASK)}. If the rank is greater than one, then @code{ANY(MASK,DIM)}
1172 is determined by applying @code{ANY} to the array sections.
1175 @item @emph{Example}:
1179 l = any((/.true., .true., .true./))
1184 integer a(2,3), b(2,3)
1188 print *, any(a .eq. b, 1)
1189 print *, any(a .eq. b, 2)
1190 end subroutine section
1191 end program test_any
1198 @section @code{ASIN} --- Arcsine function
1201 @cindex trigonometric function, sine, inverse
1202 @cindex sine, inverse
1205 @item @emph{Description}:
1206 @code{ASIN(X)} computes the arcsine of its @var{X} (inverse of @code{SIN(X)}).
1208 @item @emph{Standard}:
1209 Fortran 77 and later, for a complex argument Fortran 2008 or later
1214 @item @emph{Syntax}:
1215 @code{RESULT = ASIN(X)}
1217 @item @emph{Arguments}:
1218 @multitable @columnfractions .15 .70
1219 @item @var{X} @tab The type shall be either @code{REAL} and a magnitude that is
1220 less than or equal to one - or be @code{COMPLEX}.
1223 @item @emph{Return value}:
1224 The return value is of the same type and kind as @var{X}.
1225 The real part of the result is in radians and lies in the range
1226 @math{-\pi/2 \leq \Re \asin(x) \leq \pi/2}.
1228 @item @emph{Example}:
1231 real(8) :: x = 0.866_8
1233 end program test_asin
1236 @item @emph{Specific names}:
1237 @multitable @columnfractions .20 .20 .20 .25
1238 @item Name @tab Argument @tab Return type @tab Standard
1239 @item @code{ASIN(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 77 and later
1240 @item @code{DASIN(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 77 and later
1243 @item @emph{See also}:
1244 Inverse function: @ref{SIN}
1251 @section @code{ASINH} --- Inverse hyperbolic sine function
1254 @cindex area hyperbolic sine
1255 @cindex inverse hyperbolic sine
1256 @cindex hyperbolic function, sine, inverse
1257 @cindex sine, hyperbolic, inverse
1260 @item @emph{Description}:
1261 @code{ASINH(X)} computes the inverse hyperbolic sine of @var{X}.
1263 @item @emph{Standard}:
1264 Fortran 2008 and later
1269 @item @emph{Syntax}:
1270 @code{RESULT = ASINH(X)}
1272 @item @emph{Arguments}:
1273 @multitable @columnfractions .15 .70
1274 @item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
1277 @item @emph{Return value}:
1278 The return value is of the same type and kind as @var{X}. If @var{X} is
1279 complex, the imaginary part of the result is in radians and lies between
1280 @math{-\pi/2 \leq \Im \asinh(x) \leq \pi/2}.
1282 @item @emph{Example}:
1285 REAL(8), DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /)
1286 WRITE (*,*) ASINH(x)
1290 @item @emph{Specific names}:
1291 @multitable @columnfractions .20 .20 .20 .25
1292 @item Name @tab Argument @tab Return type @tab Standard
1293 @item @code{DASINH(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU extension.
1296 @item @emph{See also}:
1297 Inverse function: @ref{SINH}
1303 @section @code{ASSOCIATED} --- Status of a pointer or pointer/target pair
1305 @cindex pointer, status
1306 @cindex association status
1309 @item @emph{Description}:
1310 @code{ASSOCIATED(POINTER [, TARGET])} determines the status of the pointer
1311 @var{POINTER} or if @var{POINTER} is associated with the target @var{TARGET}.
1313 @item @emph{Standard}:
1314 Fortran 95 and later
1319 @item @emph{Syntax}:
1320 @code{RESULT = ASSOCIATED(POINTER [, TARGET])}
1322 @item @emph{Arguments}:
1323 @multitable @columnfractions .15 .70
1324 @item @var{POINTER} @tab @var{POINTER} shall have the @code{POINTER} attribute
1325 and it can be of any type.
1326 @item @var{TARGET} @tab (Optional) @var{TARGET} shall be a pointer or
1327 a target. It must have the same type, kind type parameter, and
1328 array rank as @var{POINTER}.
1330 The association status of neither @var{POINTER} nor @var{TARGET} shall be
1333 @item @emph{Return value}:
1334 @code{ASSOCIATED(POINTER)} returns a scalar value of type @code{LOGICAL(4)}.
1335 There are several cases:
1337 @item (A) When the optional @var{TARGET} is not present then
1338 @code{ASSOCIATED(POINTER)} is true if @var{POINTER} is associated with a target; otherwise, it returns false.
1339 @item (B) If @var{TARGET} is present and a scalar target, the result is true if
1340 @var{TARGET} is not a zero-sized storage sequence and the target associated with @var{POINTER} occupies the same storage units. If @var{POINTER} is
1341 disassociated, the result is false.
1342 @item (C) If @var{TARGET} is present and an array target, the result is true if
1343 @var{TARGET} and @var{POINTER} have the same shape, are not zero-sized arrays,
1344 are arrays whose elements are not zero-sized storage sequences, and
1345 @var{TARGET} and @var{POINTER} occupy the same storage units in array element
1347 As in case(B), the result is false, if @var{POINTER} is disassociated.
1348 @item (D) If @var{TARGET} is present and an scalar pointer, the result is true
1349 if @var{TARGET} is associated with @var{POINTER}, the target associated with
1350 @var{TARGET} are not zero-sized storage sequences and occupy the same storage
1352 The result is false, if either @var{TARGET} or @var{POINTER} is disassociated.
1353 @item (E) If @var{TARGET} is present and an array pointer, the result is true if
1354 target associated with @var{POINTER} and the target associated with @var{TARGET}
1355 have the same shape, are not zero-sized arrays, are arrays whose elements are
1356 not zero-sized storage sequences, and @var{TARGET} and @var{POINTER} occupy
1357 the same storage units in array element order.
1358 The result is false, if either @var{TARGET} or @var{POINTER} is disassociated.
1361 @item @emph{Example}:
1363 program test_associated
1365 real, target :: tgt(2) = (/1., 2./)
1366 real, pointer :: ptr(:)
1368 if (associated(ptr) .eqv. .false.) call abort
1369 if (associated(ptr,tgt) .eqv. .false.) call abort
1370 end program test_associated
1373 @item @emph{See also}:
1380 @section @code{ATAN} --- Arctangent function
1383 @cindex trigonometric function, tangent, inverse
1384 @cindex tangent, inverse
1387 @item @emph{Description}:
1388 @code{ATAN(X)} computes the arctangent of @var{X}.
1390 @item @emph{Standard}:
1391 Fortran 77 and later, for a complex argument and for two arguments
1392 Fortran 2008 or later
1397 @item @emph{Syntax}:
1398 @code{RESULT = ATAN(X)}
1399 @code{RESULT = ATAN(Y, X)}
1401 @item @emph{Arguments}:
1402 @multitable @columnfractions .15 .70
1403 @item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX};
1404 if @var{Y} is present, @var{X} shall be REAL.
1405 @item @var{Y} shall be of the same type and kind as @var{X}.
1408 @item @emph{Return value}:
1409 The return value is of the same type and kind as @var{X}.
1410 If @var{Y} is present, the result is identical to @code{ATAN2(Y,X)}.
1411 Otherwise, it the arcus tangent of @var{X}, where the real part of
1412 the result is in radians and lies in the range
1413 @math{-\pi/2 \leq \Re \atan(x) \leq \pi/2}.
1415 @item @emph{Example}:
1418 real(8) :: x = 2.866_8
1420 end program test_atan
1423 @item @emph{Specific names}:
1424 @multitable @columnfractions .20 .20 .20 .25
1425 @item Name @tab Argument @tab Return type @tab Standard
1426 @item @code{ATAN(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 77 and later
1427 @item @code{DATAN(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 77 and later
1430 @item @emph{See also}:
1431 Inverse function: @ref{TAN}
1438 @section @code{ATAN2} --- Arctangent function
1441 @cindex trigonometric function, tangent, inverse
1442 @cindex tangent, inverse
1445 @item @emph{Description}:
1446 @code{ATAN2(Y, X)} computes the principal value of the argument
1447 function of the complex number @math{X + i Y}. This function can
1448 be used to transform from Cartesian into polar coordinates and
1449 allows to determine the angle in the correct quadrant.
1451 @item @emph{Standard}:
1452 Fortran 77 and later
1457 @item @emph{Syntax}:
1458 @code{RESULT = ATAN2(Y, X)}
1460 @item @emph{Arguments}:
1461 @multitable @columnfractions .15 .70
1462 @item @var{Y} @tab The type shall be @code{REAL}.
1463 @item @var{X} @tab The type and kind type parameter shall be the same as @var{Y}.
1464 If @var{Y} is zero, then @var{X} must be nonzero.
1467 @item @emph{Return value}:
1468 The return value has the same type and kind type parameter as @var{Y}.
1469 It is the principal value of the complex number @math{X + i Y}. If
1470 @var{X} is nonzero, then it lies in the range @math{-\pi \le \atan (x) \leq \pi}.
1471 The sign is positive if @var{Y} is positive. If @var{Y} is zero, then
1472 the return value is zero if @var{X} is positive and @math{\pi} if @var{X}
1473 is negative. Finally, if @var{X} is zero, then the magnitude of the result
1476 @item @emph{Example}:
1479 real(4) :: x = 1.e0_4, y = 0.5e0_4
1481 end program test_atan2
1484 @item @emph{Specific names}:
1485 @multitable @columnfractions .20 .20 .20 .25
1486 @item Name @tab Argument @tab Return type @tab Standard
1487 @item @code{ATAN2(X, Y)} @tab @code{REAL(4) X, Y} @tab @code{REAL(4)} @tab Fortran 77 and later
1488 @item @code{DATAN2(X, Y)} @tab @code{REAL(8) X, Y} @tab @code{REAL(8)} @tab Fortran 77 and later
1495 @section @code{ATANH} --- Inverse hyperbolic tangent function
1498 @cindex area hyperbolic tangent
1499 @cindex inverse hyperbolic tangent
1500 @cindex hyperbolic function, tangent, inverse
1501 @cindex tangent, hyperbolic, inverse
1504 @item @emph{Description}:
1505 @code{ATANH(X)} computes the inverse hyperbolic tangent of @var{X}.
1507 @item @emph{Standard}:
1508 Fortran 2008 and later
1513 @item @emph{Syntax}:
1514 @code{RESULT = ATANH(X)}
1516 @item @emph{Arguments}:
1517 @multitable @columnfractions .15 .70
1518 @item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
1521 @item @emph{Return value}:
1522 The return value has same type and kind as @var{X}. If @var{X} is
1523 complex, the imaginary part of the result is in radians and lies between
1524 @math{-\pi/2 \leq \Im \atanh(x) \leq \pi/2}.
1526 @item @emph{Example}:
1529 REAL, DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /)
1530 WRITE (*,*) ATANH(x)
1534 @item @emph{Specific names}:
1535 @multitable @columnfractions .20 .20 .20 .25
1536 @item Name @tab Argument @tab Return type @tab Standard
1537 @item @code{DATANH(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU extension
1540 @item @emph{See also}:
1541 Inverse function: @ref{TANH}
1547 @section @code{BESSEL_J0} --- Bessel function of the first kind of order 0
1551 @cindex Bessel function, first kind
1554 @item @emph{Description}:
1555 @code{BESSEL_J0(X)} computes the Bessel function of the first kind of
1556 order 0 of @var{X}. This function is available under the name
1557 @code{BESJ0} as a GNU extension.
1559 @item @emph{Standard}:
1560 Fortran 2008 and later
1565 @item @emph{Syntax}:
1566 @code{RESULT = BESSEL_J0(X)}
1568 @item @emph{Arguments}:
1569 @multitable @columnfractions .15 .70
1570 @item @var{X} @tab The type shall be @code{REAL}, and it shall be scalar.
1573 @item @emph{Return value}:
1574 The return value is of type @code{REAL} and lies in the
1575 range @math{ - 0.4027... \leq Bessel (0,x) \leq 1}. It has the same
1578 @item @emph{Example}:
1581 real(8) :: x = 0.0_8
1583 end program test_besj0
1586 @item @emph{Specific names}:
1587 @multitable @columnfractions .20 .20 .20 .25
1588 @item Name @tab Argument @tab Return type @tab Standard
1589 @item @code{DBESJ0(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU extension
1596 @section @code{BESSEL_J1} --- Bessel function of the first kind of order 1
1600 @cindex Bessel function, first kind
1603 @item @emph{Description}:
1604 @code{BESSEL_J1(X)} computes the Bessel function of the first kind of
1605 order 1 of @var{X}. This function is available under the name
1606 @code{BESJ1} as a GNU extension.
1608 @item @emph{Standard}:
1614 @item @emph{Syntax}:
1615 @code{RESULT = BESSEL_J1(X)}
1617 @item @emph{Arguments}:
1618 @multitable @columnfractions .15 .70
1619 @item @var{X} @tab The type shall be @code{REAL}, and it shall be scalar.
1622 @item @emph{Return value}:
1623 The return value is of type @code{REAL} and it lies in the
1624 range @math{ - 0.5818... \leq Bessel (0,x) \leq 0.5818 }. It has the same
1627 @item @emph{Example}:
1630 real(8) :: x = 1.0_8
1632 end program test_besj1
1635 @item @emph{Specific names}:
1636 @multitable @columnfractions .20 .20 .20 .25
1637 @item Name @tab Argument @tab Return type @tab Standard
1638 @item @code{DBESJ1(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU extension
1645 @section @code{BESSEL_JN} --- Bessel function of the first kind
1649 @cindex Bessel function, first kind
1652 @item @emph{Description}:
1653 @code{BESSEL_JN(N, X)} computes the Bessel function of the first kind of
1654 order @var{N} of @var{X}. This function is available under the name
1655 @code{BESJN} as a GNU extension. If @var{N} and @var{X} are arrays,
1656 their ranks and shapes shall conform.
1658 @code{BESSEL_JN(N1, N2, X)} returns an array with the Bessel functions
1659 of the first kind of the orders @var{N1} to @var{N2}.
1661 @item @emph{Standard}:
1662 Fortran 2008 and later, negative @var{N} is allowed as GNU extension
1665 Elemental function, except for the transformational function
1666 @code{BESSEL_JN(N1, N2, X)}
1668 @item @emph{Syntax}:
1669 @code{RESULT = BESSEL_JN(N, X)}
1670 @code{RESULT = BESSEL_JN(N1, N2, X)}
1672 @item @emph{Arguments}:
1673 @multitable @columnfractions .15 .70
1674 @item @var{N} @tab Shall be a scalar or an array of type @code{INTEGER}.
1675 @item @var{N1} @tab Shall be a non-negative scalar of type @code{INTEGER}.
1676 @item @var{N2} @tab Shall be a non-negative scalar of type @code{INTEGER}.
1677 @item @var{X} @tab Shall be a scalar or an array of type @code{REAL};
1678 for @code{BESSEL_JN(N1, N2, X)} it shall be scalar.
1681 @item @emph{Return value}:
1682 The return value is a scalar of type @code{REAL}. It has the same
1686 The transformational function uses a recurrence algorithm which might,
1687 for some values of @var{X}, lead to different results than calls to
1688 the elemental function.
1690 @item @emph{Example}:
1693 real(8) :: x = 1.0_8
1695 end program test_besjn
1698 @item @emph{Specific names}:
1699 @multitable @columnfractions .20 .20 .20 .25
1700 @item Name @tab Argument @tab Return type @tab Standard
1701 @item @code{DBESJN(N, X)} @tab @code{INTEGER N} @tab @code{REAL(8)} @tab GNU extension
1702 @item @tab @code{REAL(8) X} @tab @tab
1709 @section @code{BESSEL_Y0} --- Bessel function of the second kind of order 0
1713 @cindex Bessel function, second kind
1716 @item @emph{Description}:
1717 @code{BESSEL_Y0(X)} computes the Bessel function of the second kind of
1718 order 0 of @var{X}. This function is available under the name
1719 @code{BESY0} as a GNU extension.
1721 @item @emph{Standard}:
1722 Fortran 2008 and later
1727 @item @emph{Syntax}:
1728 @code{RESULT = BESSEL_Y0(X)}
1730 @item @emph{Arguments}:
1731 @multitable @columnfractions .15 .70
1732 @item @var{X} @tab The type shall be @code{REAL}, and it shall be scalar.
1735 @item @emph{Return value}:
1736 The return value is a scalar of type @code{REAL}. It has the same
1739 @item @emph{Example}:
1742 real(8) :: x = 0.0_8
1744 end program test_besy0
1747 @item @emph{Specific names}:
1748 @multitable @columnfractions .20 .20 .20 .25
1749 @item Name @tab Argument @tab Return type @tab Standard
1750 @item @code{DBESY0(X)}@tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU extension
1757 @section @code{BESSEL_Y1} --- Bessel function of the second kind of order 1
1761 @cindex Bessel function, second kind
1764 @item @emph{Description}:
1765 @code{BESSEL_Y1(X)} computes the Bessel function of the second kind of
1766 order 1 of @var{X}. This function is available under the name
1767 @code{BESY1} as a GNU extension.
1769 @item @emph{Standard}:
1770 Fortran 2008 and later
1775 @item @emph{Syntax}:
1776 @code{RESULT = BESSEL_Y1(X)}
1778 @item @emph{Arguments}:
1779 @multitable @columnfractions .15 .70
1780 @item @var{X} @tab The type shall be @code{REAL}, and it shall be scalar.
1783 @item @emph{Return value}:
1784 The return value is a scalar of type @code{REAL}. It has the same
1787 @item @emph{Example}:
1790 real(8) :: x = 1.0_8
1792 end program test_besy1
1795 @item @emph{Specific names}:
1796 @multitable @columnfractions .20 .20 .20 .25
1797 @item Name @tab Argument @tab Return type @tab Standard
1798 @item @code{DBESY1(X)}@tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU extension
1805 @section @code{BESSEL_YN} --- Bessel function of the second kind
1809 @cindex Bessel function, second kind
1812 @item @emph{Description}:
1813 @code{BESSEL_YN(N, X)} computes the Bessel function of the second kind of
1814 order @var{N} of @var{X}. This function is available under the name
1815 @code{BESYN} as a GNU extension. If @var{N} and @var{X} are arrays,
1816 their ranks and shapes shall conform.
1818 @code{BESSEL_YN(N1, N2, X)} returns an array with the Bessel functions
1819 of the first kind of the orders @var{N1} to @var{N2}.
1821 @item @emph{Standard}:
1822 Fortran 2008 and later, negative @var{N} is allowed as GNU extension
1825 Elemental function, except for the transformational function
1826 @code{BESSEL_YN(N1, N2, X)}
1828 @item @emph{Syntax}:
1829 @code{RESULT = BESSEL_YN(N, X)}
1830 @code{RESULT = BESSEL_YN(N1, N2, X)}
1832 @item @emph{Arguments}:
1833 @multitable @columnfractions .15 .70
1834 @item @var{N} @tab Shall be a scalar or an array of type @code{INTEGER} .
1835 @item @var{N1} @tab Shall be a non-negative scalar of type @code{INTEGER}.
1836 @item @var{N2} @tab Shall be a non-negative scalar of type @code{INTEGER}.
1837 @item @var{X} @tab Shall be a scalar or an array of type @code{REAL};
1838 for @code{BESSEL_YN(N1, N2, X)} it shall be scalar.
1841 @item @emph{Return value}:
1842 The return value is a scalar of type @code{REAL}. It has the same
1846 The transformational function uses a recurrence algorithm which might,
1847 for some values of @var{X}, lead to different results than calls to
1848 the elemental function.
1850 @item @emph{Example}:
1853 real(8) :: x = 1.0_8
1855 end program test_besyn
1858 @item @emph{Specific names}:
1859 @multitable @columnfractions .20 .20 .20 .25
1860 @item Name @tab Argument @tab Return type @tab Standard
1861 @item @code{DBESYN(N,X)} @tab @code{INTEGER N} @tab @code{REAL(8)} @tab GNU extension
1862 @item @tab @code{REAL(8) X} @tab @tab
1869 @section @code{BGE} --- Bitwise greater than or equal to
1871 @cindex bitwise comparison
1874 @item @emph{Description}:
1875 Determines whether an integral is a bitwise greater than or equal to
1878 @item @emph{Standard}:
1879 Fortran 2008 and later
1884 @item @emph{Syntax}:
1885 @code{RESULT = BGE(I, J)}
1887 @item @emph{Arguments}:
1888 @multitable @columnfractions .15 .70
1889 @item @var{I} @tab Shall be of @code{INTEGER} type.
1890 @item @var{J} @tab Shall be of @code{INTEGER} type, and of the same kind
1894 @item @emph{Return value}:
1895 The return value is of type @code{LOGICAL} and of the default kind.
1897 @item @emph{See also}:
1898 @ref{BGT}, @ref{BLE}, @ref{BLT}
1904 @section @code{BGT} --- Bitwise greater than
1906 @cindex bitwise comparison
1909 @item @emph{Description}:
1910 Determines whether an integral is a bitwise greater than another.
1912 @item @emph{Standard}:
1913 Fortran 2008 and later
1918 @item @emph{Syntax}:
1919 @code{RESULT = BGT(I, J)}
1921 @item @emph{Arguments}:
1922 @multitable @columnfractions .15 .70
1923 @item @var{I} @tab Shall be of @code{INTEGER} type.
1924 @item @var{J} @tab Shall be of @code{INTEGER} type, and of the same kind
1928 @item @emph{Return value}:
1929 The return value is of type @code{LOGICAL} and of the default kind.
1931 @item @emph{See also}:
1932 @ref{BGE}, @ref{BLE}, @ref{BLT}
1938 @section @code{BIT_SIZE} --- Bit size inquiry function
1940 @cindex bits, number of
1941 @cindex size of a variable, in bits
1944 @item @emph{Description}:
1945 @code{BIT_SIZE(I)} returns the number of bits (integer precision plus sign bit)
1946 represented by the type of @var{I}. The result of @code{BIT_SIZE(I)} is
1947 independent of the actual value of @var{I}.
1949 @item @emph{Standard}:
1950 Fortran 95 and later
1955 @item @emph{Syntax}:
1956 @code{RESULT = BIT_SIZE(I)}
1958 @item @emph{Arguments}:
1959 @multitable @columnfractions .15 .70
1960 @item @var{I} @tab The type shall be @code{INTEGER}.
1963 @item @emph{Return value}:
1964 The return value is of type @code{INTEGER}
1966 @item @emph{Example}:
1968 program test_bit_size
1973 end program test_bit_size
1980 @section @code{BLE} --- Bitwise less than or equal to
1982 @cindex bitwise comparison
1985 @item @emph{Description}:
1986 Determines whether an integral is a bitwise less than or equal to
1989 @item @emph{Standard}:
1990 Fortran 2008 and later
1995 @item @emph{Syntax}:
1996 @code{RESULT = BLE(I, J)}
1998 @item @emph{Arguments}:
1999 @multitable @columnfractions .15 .70
2000 @item @var{I} @tab Shall be of @code{INTEGER} type.
2001 @item @var{J} @tab Shall be of @code{INTEGER} type, and of the same kind
2005 @item @emph{Return value}:
2006 The return value is of type @code{LOGICAL} and of the default kind.
2008 @item @emph{See also}:
2009 @ref{BGT}, @ref{BGE}, @ref{BLT}
2015 @section @code{BLT} --- Bitwise less than
2017 @cindex bitwise comparison
2020 @item @emph{Description}:
2021 Determines whether an integral is a bitwise less than another.
2023 @item @emph{Standard}:
2024 Fortran 2008 and later
2029 @item @emph{Syntax}:
2030 @code{RESULT = BLT(I, J)}
2032 @item @emph{Arguments}:
2033 @multitable @columnfractions .15 .70
2034 @item @var{I} @tab Shall be of @code{INTEGER} type.
2035 @item @var{J} @tab Shall be of @code{INTEGER} type, and of the same kind
2039 @item @emph{Return value}:
2040 The return value is of type @code{LOGICAL} and of the default kind.
2042 @item @emph{See also}:
2043 @ref{BGE}, @ref{BGT}, @ref{BLE}
2049 @section @code{BTEST} --- Bit test function
2051 @cindex bits, testing
2054 @item @emph{Description}:
2055 @code{BTEST(I,POS)} returns logical @code{.TRUE.} if the bit at @var{POS}
2056 in @var{I} is set. The counting of the bits starts at 0.
2058 @item @emph{Standard}:
2059 Fortran 95 and later
2064 @item @emph{Syntax}:
2065 @code{RESULT = BTEST(I, POS)}
2067 @item @emph{Arguments}:
2068 @multitable @columnfractions .15 .70
2069 @item @var{I} @tab The type shall be @code{INTEGER}.
2070 @item @var{POS} @tab The type shall be @code{INTEGER}.
2073 @item @emph{Return value}:
2074 The return value is of type @code{LOGICAL}
2076 @item @emph{Example}:
2079 integer :: i = 32768 + 1024 + 64
2083 bool = btest(i, pos)
2086 end program test_btest
2092 @section @code{C_ASSOCIATED} --- Status of a C pointer
2093 @fnindex C_ASSOCIATED
2094 @cindex association status, C pointer
2095 @cindex pointer, C association status
2098 @item @emph{Description}:
2099 @code{C_ASSOCIATED(c_prt_1[, c_ptr_2])} determines the status of the C pointer
2100 @var{c_ptr_1} or if @var{c_ptr_1} is associated with the target @var{c_ptr_2}.
2102 @item @emph{Standard}:
2103 Fortran 2003 and later
2108 @item @emph{Syntax}:
2109 @code{RESULT = C_ASSOCIATED(c_prt_1[, c_ptr_2])}
2111 @item @emph{Arguments}:
2112 @multitable @columnfractions .15 .70
2113 @item @var{c_ptr_1} @tab Scalar of the type @code{C_PTR} or @code{C_FUNPTR}.
2114 @item @var{c_ptr_2} @tab (Optional) Scalar of the same type as @var{c_ptr_1}.
2117 @item @emph{Return value}:
2118 The return value is of type @code{LOGICAL}; it is @code{.false.} if either
2119 @var{c_ptr_1} is a C NULL pointer or if @var{c_ptr1} and @var{c_ptr_2}
2120 point to different addresses.
2122 @item @emph{Example}:
2124 subroutine association_test(a,b)
2125 use iso_c_binding, only: c_associated, c_loc, c_ptr
2129 if(c_associated(b, c_loc(a))) &
2130 stop 'b and a do not point to same target'
2131 end subroutine association_test
2134 @item @emph{See also}:
2135 @ref{C_LOC}, @ref{C_FUNLOC}
2140 @section @code{C_FUNLOC} --- Obtain the C address of a procedure
2142 @cindex pointer, C address of procedures
2145 @item @emph{Description}:
2146 @code{C_FUNLOC(x)} determines the C address of the argument.
2148 @item @emph{Standard}:
2149 Fortran 2003 and later
2154 @item @emph{Syntax}:
2155 @code{RESULT = C_FUNLOC(x)}
2157 @item @emph{Arguments}:
2158 @multitable @columnfractions .15 .70
2159 @item @var{x} @tab Interoperable function or pointer to such function.
2162 @item @emph{Return value}:
2163 The return value is of type @code{C_FUNPTR} and contains the C address
2166 @item @emph{Example}:
2172 subroutine sub(a) bind(c)
2182 subroutine my_routine(p) bind(c,name='myC_func')
2184 type(c_funptr), intent(in) :: p
2187 call my_routine(c_funloc(sub))
2191 @item @emph{See also}:
2192 @ref{C_ASSOCIATED}, @ref{C_LOC}, @ref{C_F_POINTER}, @ref{C_F_PROCPOINTER}
2196 @node C_F_PROCPOINTER
2197 @section @code{C_F_PROCPOINTER} --- Convert C into Fortran procedure pointer
2198 @fnindex C_F_PROCPOINTER
2199 @cindex pointer, C address of pointers
2202 @item @emph{Description}:
2203 @code{C_F_PROCPOINTER(CPTR, FPTR)} Assign the target of the C function pointer
2204 @var{CPTR} to the Fortran procedure pointer @var{FPTR}.
2206 @item @emph{Standard}:
2207 Fortran 2003 and later
2212 @item @emph{Syntax}:
2213 @code{CALL C_F_PROCPOINTER(cptr, fptr)}
2215 @item @emph{Arguments}:
2216 @multitable @columnfractions .15 .70
2217 @item @var{CPTR} @tab scalar of the type @code{C_FUNPTR}. It is
2219 @item @var{FPTR} @tab procedure pointer interoperable with @var{cptr}. It is
2223 @item @emph{Example}:
2231 real(c_float), intent(in) :: a
2232 real(c_float) :: func
2236 function getIterFunc() bind(c,name="getIterFunc")
2238 type(c_funptr) :: getIterFunc
2241 type(c_funptr) :: cfunptr
2242 procedure(func), pointer :: myFunc
2243 cfunptr = getIterFunc()
2244 call c_f_procpointer(cfunptr, myFunc)
2248 @item @emph{See also}:
2249 @ref{C_LOC}, @ref{C_F_POINTER}
2254 @section @code{C_F_POINTER} --- Convert C into Fortran pointer
2255 @fnindex C_F_POINTER
2256 @cindex pointer, convert C to Fortran
2259 @item @emph{Description}:
2260 @code{C_F_POINTER(CPTR, FPTR[, SHAPE])} Assign the target the C pointer
2261 @var{CPTR} to the Fortran pointer @var{FPTR} and specify its
2264 @item @emph{Standard}:
2265 Fortran 2003 and later
2270 @item @emph{Syntax}:
2271 @code{CALL C_F_POINTER(CPTR, FPTR[, SHAPE])}
2273 @item @emph{Arguments}:
2274 @multitable @columnfractions .15 .70
2275 @item @var{CPTR} @tab scalar of the type @code{C_PTR}. It is
2277 @item @var{FPTR} @tab pointer interoperable with @var{cptr}. It is
2279 @item @var{SHAPE} @tab (Optional) Rank-one array of type @code{INTEGER}
2280 with @code{INTENT(IN)}. It shall be present
2281 if and only if @var{fptr} is an array. The size
2282 must be equal to the rank of @var{fptr}.
2285 @item @emph{Example}:
2291 subroutine my_routine(p) bind(c,name='myC_func')
2293 type(c_ptr), intent(out) :: p
2297 real,pointer :: a(:)
2298 call my_routine(cptr)
2299 call c_f_pointer(cptr, a, [12])
2303 @item @emph{See also}:
2304 @ref{C_LOC}, @ref{C_F_PROCPOINTER}
2309 @section @code{C_LOC} --- Obtain the C address of an object
2311 @cindex procedure pointer, convert C to Fortran
2314 @item @emph{Description}:
2315 @code{C_LOC(X)} determines the C address of the argument.
2317 @item @emph{Standard}:
2318 Fortran 2003 and later
2323 @item @emph{Syntax}:
2324 @code{RESULT = C_LOC(X)}
2326 @item @emph{Arguments}:
2327 @multitable @columnfractions .10 .75
2328 @item @var{X} @tab Shall have either the POINTER or TARGET attribute. It shall not be a coindexed object. It shall either be a variable with interoperable type and kind type parameters, or be a scalar, nonpolymorphic variable with no length type parameters.
2332 @item @emph{Return value}:
2333 The return value is of type @code{C_PTR} and contains the C address
2336 @item @emph{Example}:
2338 subroutine association_test(a,b)
2339 use iso_c_binding, only: c_associated, c_loc, c_ptr
2343 if(c_associated(b, c_loc(a))) &
2344 stop 'b and a do not point to same target'
2345 end subroutine association_test
2348 @item @emph{See also}:
2349 @ref{C_ASSOCIATED}, @ref{C_FUNLOC}, @ref{C_F_POINTER}, @ref{C_F_PROCPOINTER}
2354 @section @code{C_SIZEOF} --- Size in bytes of an expression
2356 @cindex expression size
2357 @cindex size of an expression
2360 @item @emph{Description}:
2361 @code{C_SIZEOF(X)} calculates the number of bytes of storage the
2362 expression @code{X} occupies.
2364 @item @emph{Standard}:
2368 Inquiry function of the module @code{ISO_C_BINDING}
2370 @item @emph{Syntax}:
2371 @code{N = C_SIZEOF(X)}
2373 @item @emph{Arguments}:
2374 @multitable @columnfractions .15 .70
2375 @item @var{X} @tab The argument shall be an interoperable data entity.
2378 @item @emph{Return value}:
2379 The return value is of type integer and of the system-dependent kind
2380 @code{C_SIZE_T} (from the @code{ISO_C_BINDING} module). Its value is the
2381 number of bytes occupied by the argument. If the argument has the
2382 @code{POINTER} attribute, the number of bytes of the storage area pointed
2383 to is returned. If the argument is of a derived type with @code{POINTER}
2384 or @code{ALLOCATABLE} components, the return value doesn't account for
2385 the sizes of the data pointed to by these components.
2387 @item @emph{Example}:
2391 real(c_float) :: r, s(5)
2392 print *, (c_sizeof(s)/c_sizeof(r) == 5)
2395 The example will print @code{.TRUE.} unless you are using a platform
2396 where default @code{REAL} variables are unusually padded.
2398 @item @emph{See also}:
2399 @ref{SIZEOF}, @ref{STORAGE_SIZE}
2404 @section @code{CEILING} --- Integer ceiling function
2407 @cindex rounding, ceiling
2410 @item @emph{Description}:
2411 @code{CEILING(A)} returns the least integer greater than or equal to @var{A}.
2413 @item @emph{Standard}:
2414 Fortran 95 and later
2419 @item @emph{Syntax}:
2420 @code{RESULT = CEILING(A [, KIND])}
2422 @item @emph{Arguments}:
2423 @multitable @columnfractions .15 .70
2424 @item @var{A} @tab The type shall be @code{REAL}.
2425 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
2426 expression indicating the kind parameter of the result.
2429 @item @emph{Return value}:
2430 The return value is of type @code{INTEGER(KIND)} if @var{KIND} is present
2431 and a default-kind @code{INTEGER} otherwise.
2433 @item @emph{Example}:
2435 program test_ceiling
2438 print *, ceiling(x) ! returns 64
2439 print *, ceiling(y) ! returns -63
2440 end program test_ceiling
2443 @item @emph{See also}:
2444 @ref{FLOOR}, @ref{NINT}
2451 @section @code{CHAR} --- Character conversion function
2453 @cindex conversion, to character
2456 @item @emph{Description}:
2457 @code{CHAR(I [, KIND])} returns the character represented by the integer @var{I}.
2459 @item @emph{Standard}:
2460 Fortran 77 and later
2465 @item @emph{Syntax}:
2466 @code{RESULT = CHAR(I [, KIND])}
2468 @item @emph{Arguments}:
2469 @multitable @columnfractions .15 .70
2470 @item @var{I} @tab The type shall be @code{INTEGER}.
2471 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
2472 expression indicating the kind parameter of the result.
2475 @item @emph{Return value}:
2476 The return value is of type @code{CHARACTER(1)}
2478 @item @emph{Example}:
2484 print *, i, c ! returns 'J'
2485 end program test_char
2488 @item @emph{Specific names}:
2489 @multitable @columnfractions .20 .20 .20 .25
2490 @item Name @tab Argument @tab Return type @tab Standard
2491 @item @code{CHAR(I)} @tab @code{INTEGER I} @tab @code{CHARACTER(LEN=1)} @tab F77 and later
2495 See @ref{ICHAR} for a discussion of converting between numerical values
2496 and formatted string representations.
2498 @item @emph{See also}:
2499 @ref{ACHAR}, @ref{IACHAR}, @ref{ICHAR}
2506 @section @code{CHDIR} --- Change working directory
2508 @cindex system, working directory
2511 @item @emph{Description}:
2512 Change current working directory to a specified path.
2514 This intrinsic is provided in both subroutine and function forms; however,
2515 only one form can be used in any given program unit.
2517 @item @emph{Standard}:
2521 Subroutine, function
2523 @item @emph{Syntax}:
2524 @multitable @columnfractions .80
2525 @item @code{CALL CHDIR(NAME [, STATUS])}
2526 @item @code{STATUS = CHDIR(NAME)}
2529 @item @emph{Arguments}:
2530 @multitable @columnfractions .15 .70
2531 @item @var{NAME} @tab The type shall be @code{CHARACTER} of default
2532 kind and shall specify a valid path within the file system.
2533 @item @var{STATUS} @tab (Optional) @code{INTEGER} status flag of the default
2534 kind. Returns 0 on success, and a system specific and nonzero error code
2538 @item @emph{Example}:
2541 CHARACTER(len=255) :: path
2543 WRITE(*,*) TRIM(path)
2546 WRITE(*,*) TRIM(path)
2550 @item @emph{See also}:
2557 @section @code{CHMOD} --- Change access permissions of files
2559 @cindex file system, change access mode
2562 @item @emph{Description}:
2563 @code{CHMOD} changes the permissions of a file. This function invokes
2564 @code{/bin/chmod} and might therefore not work on all platforms.
2566 This intrinsic is provided in both subroutine and function forms; however,
2567 only one form can be used in any given program unit.
2569 @item @emph{Standard}:
2573 Subroutine, function
2575 @item @emph{Syntax}:
2576 @multitable @columnfractions .80
2577 @item @code{CALL CHMOD(NAME, MODE[, STATUS])}
2578 @item @code{STATUS = CHMOD(NAME, MODE)}
2581 @item @emph{Arguments}:
2582 @multitable @columnfractions .15 .70
2584 @item @var{NAME} @tab Scalar @code{CHARACTER} of default kind with the
2585 file name. Trailing blanks are ignored unless the character
2586 @code{achar(0)} is present, then all characters up to and excluding
2587 @code{achar(0)} are used as the file name.
2589 @item @var{MODE} @tab Scalar @code{CHARACTER} of default kind giving the
2590 file permission. @var{MODE} uses the same syntax as the @var{MODE}
2591 argument of @code{/bin/chmod}.
2593 @item @var{STATUS} @tab (optional) scalar @code{INTEGER}, which is
2594 @code{0} on success and nonzero otherwise.
2597 @item @emph{Return value}:
2598 In either syntax, @var{STATUS} is set to @code{0} on success and nonzero
2601 @item @emph{Example}:
2602 @code{CHMOD} as subroutine
2607 call chmod('test.dat','u+x',status)
2608 print *, 'Status: ', status
2609 end program chmod_test
2611 @code{CHMOD} as function:
2616 status = chmod('test.dat','u+x')
2617 print *, 'Status: ', status
2618 end program chmod_test
2626 @section @code{CMPLX} --- Complex conversion function
2628 @cindex complex numbers, conversion to
2629 @cindex conversion, to complex
2632 @item @emph{Description}:
2633 @code{CMPLX(X [, Y [, KIND]])} returns a complex number where @var{X} is converted to
2634 the real component. If @var{Y} is present it is converted to the imaginary
2635 component. If @var{Y} is not present then the imaginary component is set to
2636 0.0. If @var{X} is complex then @var{Y} must not be present.
2638 @item @emph{Standard}:
2639 Fortran 77 and later
2644 @item @emph{Syntax}:
2645 @code{RESULT = CMPLX(X [, Y [, KIND]])}
2647 @item @emph{Arguments}:
2648 @multitable @columnfractions .15 .70
2649 @item @var{X} @tab The type may be @code{INTEGER}, @code{REAL},
2651 @item @var{Y} @tab (Optional; only allowed if @var{X} is not
2652 @code{COMPLEX}.) May be @code{INTEGER} or @code{REAL}.
2653 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
2654 expression indicating the kind parameter of the result.
2657 @item @emph{Return value}:
2658 The return value is of @code{COMPLEX} type, with a kind equal to
2659 @var{KIND} if it is specified. If @var{KIND} is not specified, the
2660 result is of the default @code{COMPLEX} kind, regardless of the kinds of
2661 @var{X} and @var{Y}.
2663 @item @emph{Example}:
2670 print *, z, cmplx(x)
2671 end program test_cmplx
2674 @item @emph{See also}:
2680 @node COMMAND_ARGUMENT_COUNT
2681 @section @code{COMMAND_ARGUMENT_COUNT} --- Get number of command line arguments
2682 @fnindex COMMAND_ARGUMENT_COUNT
2683 @cindex command-line arguments
2684 @cindex command-line arguments, number of
2685 @cindex arguments, to program
2688 @item @emph{Description}:
2689 @code{COMMAND_ARGUMENT_COUNT()} returns the number of arguments passed on the
2690 command line when the containing program was invoked.
2692 @item @emph{Standard}:
2693 Fortran 2003 and later
2698 @item @emph{Syntax}:
2699 @code{RESULT = COMMAND_ARGUMENT_COUNT()}
2701 @item @emph{Arguments}:
2702 @multitable @columnfractions .15 .70
2706 @item @emph{Return value}:
2707 The return value is an @code{INTEGER} of default kind.
2709 @item @emph{Example}:
2711 program test_command_argument_count
2713 count = command_argument_count()
2715 end program test_command_argument_count
2718 @item @emph{See also}:
2719 @ref{GET_COMMAND}, @ref{GET_COMMAND_ARGUMENT}
2724 @node COMPILER_OPTIONS
2725 @section @code{COMPILER_OPTIONS} --- Options passed to the compiler
2726 @fnindex COMPILER_OPTIONS
2727 @cindex flags inquiry function
2728 @cindex options inquiry function
2729 @cindex compiler flags inquiry function
2732 @item @emph{Description}:
2733 @code{COMPILER_OPTIONS()} returns a string with the options used for
2736 @item @emph{Standard}:
2740 Inquiry function of the module @code{ISO_FORTRAN_ENV}
2742 @item @emph{Syntax}:
2743 @code{STR = COMPILER_OPTIONS()}
2745 @item @emph{Arguments}:
2748 @item @emph{Return value}:
2749 The return value is a default-kind string with system-dependent length.
2750 It contains the compiler flags used to compile the file, which called
2751 the @code{COMPILER_OPTIONS} intrinsic.
2753 @item @emph{Example}:
2756 print '(4a)', 'This file was compiled by ', &
2757 compiler_version(), ' using the the options ', &
2762 @item @emph{See also}:
2763 @ref{COMPILER_VERSION}, @ref{ISO_FORTRAN_ENV}
2768 @node COMPILER_VERSION
2769 @section @code{COMPILER_VERSION} --- Compiler version string
2770 @fnindex COMPILER_VERSION
2771 @cindex compiler, name and version
2772 @cindex version of the compiler
2775 @item @emph{Description}:
2776 @code{COMPILER_VERSION()} returns a string with the name and the
2777 version of the compiler.
2779 @item @emph{Standard}:
2783 Inquiry function of the module @code{ISO_FORTRAN_ENV}
2785 @item @emph{Syntax}:
2786 @code{STR = COMPILER_VERSION()}
2788 @item @emph{Arguments}:
2791 @item @emph{Return value}:
2792 The return value is a default-kind string with system-dependent length.
2793 It contains the name of the compiler and its version number.
2795 @item @emph{Example}:
2798 print '(4a)', 'This file was compiled by ', &
2799 compiler_version(), ' using the the options ', &
2804 @item @emph{See also}:
2805 @ref{COMPILER_OPTIONS}, @ref{ISO_FORTRAN_ENV}
2811 @section @code{COMPLEX} --- Complex conversion function
2813 @cindex complex numbers, conversion to
2814 @cindex conversion, to complex
2817 @item @emph{Description}:
2818 @code{COMPLEX(X, Y)} returns a complex number where @var{X} is converted
2819 to the real component and @var{Y} is converted to the imaginary
2822 @item @emph{Standard}:
2828 @item @emph{Syntax}:
2829 @code{RESULT = COMPLEX(X, Y)}
2831 @item @emph{Arguments}:
2832 @multitable @columnfractions .15 .70
2833 @item @var{X} @tab The type may be @code{INTEGER} or @code{REAL}.
2834 @item @var{Y} @tab The type may be @code{INTEGER} or @code{REAL}.
2837 @item @emph{Return value}:
2838 If @var{X} and @var{Y} are both of @code{INTEGER} type, then the return
2839 value is of default @code{COMPLEX} type.
2841 If @var{X} and @var{Y} are of @code{REAL} type, or one is of @code{REAL}
2842 type and one is of @code{INTEGER} type, then the return value is of
2843 @code{COMPLEX} type with a kind equal to that of the @code{REAL}
2844 argument with the highest precision.
2846 @item @emph{Example}:
2848 program test_complex
2851 print *, complex(i, x)
2852 end program test_complex
2855 @item @emph{See also}:
2862 @section @code{CONJG} --- Complex conjugate function
2865 @cindex complex conjugate
2868 @item @emph{Description}:
2869 @code{CONJG(Z)} returns the conjugate of @var{Z}. If @var{Z} is @code{(x, y)}
2870 then the result is @code{(x, -y)}
2872 @item @emph{Standard}:
2873 Fortran 77 and later, has overloads that are GNU extensions
2878 @item @emph{Syntax}:
2881 @item @emph{Arguments}:
2882 @multitable @columnfractions .15 .70
2883 @item @var{Z} @tab The type shall be @code{COMPLEX}.
2886 @item @emph{Return value}:
2887 The return value is of type @code{COMPLEX}.
2889 @item @emph{Example}:
2892 complex :: z = (2.0, 3.0)
2893 complex(8) :: dz = (2.71_8, -3.14_8)
2898 end program test_conjg
2901 @item @emph{Specific names}:
2902 @multitable @columnfractions .20 .20 .20 .25
2903 @item Name @tab Argument @tab Return type @tab Standard
2904 @item @code{CONJG(Z)} @tab @code{COMPLEX Z} @tab @code{COMPLEX} @tab GNU extension
2905 @item @code{DCONJG(Z)} @tab @code{COMPLEX(8) Z} @tab @code{COMPLEX(8)} @tab GNU extension
2912 @section @code{COS} --- Cosine function
2918 @cindex trigonometric function, cosine
2922 @item @emph{Description}:
2923 @code{COS(X)} computes the cosine of @var{X}.
2925 @item @emph{Standard}:
2926 Fortran 77 and later, has overloads that are GNU extensions
2931 @item @emph{Syntax}:
2932 @code{RESULT = COS(X)}
2934 @item @emph{Arguments}:
2935 @multitable @columnfractions .15 .70
2936 @item @var{X} @tab The type shall be @code{REAL} or
2940 @item @emph{Return value}:
2941 The return value is of the same type and kind as @var{X}. The real part
2942 of the result is in radians. If @var{X} is of the type @code{REAL},
2943 the return value lies in the range @math{ -1 \leq \cos (x) \leq 1}.
2945 @item @emph{Example}:
2950 end program test_cos
2953 @item @emph{Specific names}:
2954 @multitable @columnfractions .20 .20 .20 .25
2955 @item Name @tab Argument @tab Return type @tab Standard
2956 @item @code{COS(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 77 and later
2957 @item @code{DCOS(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 77 and later
2958 @item @code{CCOS(X)} @tab @code{COMPLEX(4) X} @tab @code{COMPLEX(4)} @tab Fortran 77 and later
2959 @item @code{ZCOS(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
2960 @item @code{CDCOS(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
2963 @item @emph{See also}:
2964 Inverse function: @ref{ACOS}
2971 @section @code{COSH} --- Hyperbolic cosine function
2974 @cindex hyperbolic cosine
2975 @cindex hyperbolic function, cosine
2976 @cindex cosine, hyperbolic
2979 @item @emph{Description}:
2980 @code{COSH(X)} computes the hyperbolic cosine of @var{X}.
2982 @item @emph{Standard}:
2983 Fortran 77 and later, for a complex argument Fortran 2008 or later
2988 @item @emph{Syntax}:
2991 @item @emph{Arguments}:
2992 @multitable @columnfractions .15 .70
2993 @item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
2996 @item @emph{Return value}:
2997 The return value has same type and kind as @var{X}. If @var{X} is
2998 complex, the imaginary part of the result is in radians. If @var{X}
2999 is @code{REAL}, the return value has a lower bound of one,
3000 @math{\cosh (x) \geq 1}.
3002 @item @emph{Example}:
3005 real(8) :: x = 1.0_8
3007 end program test_cosh
3010 @item @emph{Specific names}:
3011 @multitable @columnfractions .20 .20 .20 .25
3012 @item Name @tab Argument @tab Return type @tab Standard
3013 @item @code{COSH(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 77 and later
3014 @item @code{DCOSH(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 77 and later
3017 @item @emph{See also}:
3018 Inverse function: @ref{ACOSH}
3025 @section @code{COUNT} --- Count function
3027 @cindex array, conditionally count elements
3028 @cindex array, element counting
3029 @cindex array, number of elements
3032 @item @emph{Description}:
3034 Counts the number of @code{.TRUE.} elements in a logical @var{MASK},
3035 or, if the @var{DIM} argument is supplied, counts the number of
3036 elements along each row of the array in the @var{DIM} direction.
3037 If the array has zero size, or all of the elements of @var{MASK} are
3038 @code{.FALSE.}, then the result is @code{0}.
3040 @item @emph{Standard}:
3041 Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
3044 Transformational function
3046 @item @emph{Syntax}:
3047 @code{RESULT = COUNT(MASK [, DIM, KIND])}
3049 @item @emph{Arguments}:
3050 @multitable @columnfractions .15 .70
3051 @item @var{MASK} @tab The type shall be @code{LOGICAL}.
3052 @item @var{DIM} @tab (Optional) The type shall be @code{INTEGER}.
3053 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
3054 expression indicating the kind parameter of the result.
3057 @item @emph{Return value}:
3058 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
3059 @var{KIND} is absent, the return value is of default integer kind.
3060 If @var{DIM} is present, the result is an array with a rank one less
3061 than the rank of @var{ARRAY}, and a size corresponding to the shape
3062 of @var{ARRAY} with the @var{DIM} dimension removed.
3064 @item @emph{Example}:
3067 integer, dimension(2,3) :: a, b
3068 logical, dimension(2,3) :: mask
3069 a = reshape( (/ 1, 2, 3, 4, 5, 6 /), (/ 2, 3 /))
3070 b = reshape( (/ 0, 7, 3, 4, 5, 8 /), (/ 2, 3 /))
3071 print '(3i3)', a(1,:)
3072 print '(3i3)', a(2,:)
3074 print '(3i3)', b(1,:)
3075 print '(3i3)', b(2,:)
3078 print '(3l3)', mask(1,:)
3079 print '(3l3)', mask(2,:)
3081 print '(3i3)', count(mask)
3083 print '(3i3)', count(mask, 1)
3085 print '(3i3)', count(mask, 2)
3086 end program test_count
3093 @section @code{CPU_TIME} --- CPU elapsed time in seconds
3095 @cindex time, elapsed
3098 @item @emph{Description}:
3099 Returns a @code{REAL} value representing the elapsed CPU time in
3100 seconds. This is useful for testing segments of code to determine
3103 If a time source is available, time will be reported with microsecond
3104 resolution. If no time source is available, @var{TIME} is set to
3107 Note that @var{TIME} may contain a, system dependent, arbitrary offset
3108 and may not start with @code{0.0}. For @code{CPU_TIME}, the absolute
3109 value is meaningless, only differences between subsequent calls to
3110 this subroutine, as shown in the example below, should be used.
3113 @item @emph{Standard}:
3114 Fortran 95 and later
3119 @item @emph{Syntax}:
3120 @code{CALL CPU_TIME(TIME)}
3122 @item @emph{Arguments}:
3123 @multitable @columnfractions .15 .70
3124 @item @var{TIME} @tab The type shall be @code{REAL} with @code{INTENT(OUT)}.
3127 @item @emph{Return value}:
3130 @item @emph{Example}:
3132 program test_cpu_time
3133 real :: start, finish
3134 call cpu_time(start)
3135 ! put code to test here
3136 call cpu_time(finish)
3137 print '("Time = ",f6.3," seconds.")',finish-start
3138 end program test_cpu_time
3141 @item @emph{See also}:
3142 @ref{SYSTEM_CLOCK}, @ref{DATE_AND_TIME}
3148 @section @code{CSHIFT} --- Circular shift elements of an array
3150 @cindex array, shift circularly
3151 @cindex array, permutation
3152 @cindex array, rotate
3155 @item @emph{Description}:
3156 @code{CSHIFT(ARRAY, SHIFT [, DIM])} performs a circular shift on elements of
3157 @var{ARRAY} along the dimension of @var{DIM}. If @var{DIM} is omitted it is
3158 taken to be @code{1}. @var{DIM} is a scalar of type @code{INTEGER} in the
3159 range of @math{1 \leq DIM \leq n)} where @math{n} is the rank of @var{ARRAY}.
3160 If the rank of @var{ARRAY} is one, then all elements of @var{ARRAY} are shifted
3161 by @var{SHIFT} places. If rank is greater than one, then all complete rank one
3162 sections of @var{ARRAY} along the given dimension are shifted. Elements
3163 shifted out one end of each rank one section are shifted back in the other end.
3165 @item @emph{Standard}:
3166 Fortran 95 and later
3169 Transformational function
3171 @item @emph{Syntax}:
3172 @code{RESULT = CSHIFT(ARRAY, SHIFT [, DIM])}
3174 @item @emph{Arguments}:
3175 @multitable @columnfractions .15 .70
3176 @item @var{ARRAY} @tab Shall be an array of any type.
3177 @item @var{SHIFT} @tab The type shall be @code{INTEGER}.
3178 @item @var{DIM} @tab The type shall be @code{INTEGER}.
3181 @item @emph{Return value}:
3182 Returns an array of same type and rank as the @var{ARRAY} argument.
3184 @item @emph{Example}:
3187 integer, dimension(3,3) :: a
3188 a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /))
3189 print '(3i3)', a(1,:)
3190 print '(3i3)', a(2,:)
3191 print '(3i3)', a(3,:)
3192 a = cshift(a, SHIFT=(/1, 2, -1/), DIM=2)
3194 print '(3i3)', a(1,:)
3195 print '(3i3)', a(2,:)
3196 print '(3i3)', a(3,:)
3197 end program test_cshift
3204 @section @code{CTIME} --- Convert a time into a string
3206 @cindex time, conversion to string
3207 @cindex conversion, to string
3210 @item @emph{Description}:
3211 @code{CTIME} converts a system time value, such as returned by
3212 @code{TIME8()}, to a string of the form @samp{Sat Aug 19 18:13:14 1995}.
3214 This intrinsic is provided in both subroutine and function forms; however,
3215 only one form can be used in any given program unit.
3217 @item @emph{Standard}:
3221 Subroutine, function
3223 @item @emph{Syntax}:
3224 @multitable @columnfractions .80
3225 @item @code{CALL CTIME(TIME, RESULT)}.
3226 @item @code{RESULT = CTIME(TIME)}, (not recommended).
3229 @item @emph{Arguments}:
3230 @multitable @columnfractions .15 .70
3231 @item @var{TIME} @tab The type shall be of type @code{INTEGER(KIND=8)}.
3232 @item @var{RESULT} @tab The type shall be of type @code{CHARACTER} and
3236 @item @emph{Return value}:
3237 The converted date and time as a string.
3239 @item @emph{Example}:
3243 character(len=30) :: date
3246 ! Do something, main part of the program
3249 print *, 'Program was started on ', date
3250 end program test_ctime
3253 @item @emph{See Also}:
3254 @ref{GMTIME}, @ref{LTIME}, @ref{TIME}, @ref{TIME8}
3260 @section @code{DATE_AND_TIME} --- Date and time subroutine
3261 @fnindex DATE_AND_TIME
3262 @cindex date, current
3263 @cindex current date
3264 @cindex time, current
3265 @cindex current time
3268 @item @emph{Description}:
3269 @code{DATE_AND_TIME(DATE, TIME, ZONE, VALUES)} gets the corresponding date and
3270 time information from the real-time system clock. @var{DATE} is
3271 @code{INTENT(OUT)} and has form ccyymmdd. @var{TIME} is @code{INTENT(OUT)} and
3272 has form hhmmss.sss. @var{ZONE} is @code{INTENT(OUT)} and has form (+-)hhmm,
3273 representing the difference with respect to Coordinated Universal Time (UTC).
3274 Unavailable time and date parameters return blanks.
3276 @var{VALUES} is @code{INTENT(OUT)} and provides the following:
3278 @multitable @columnfractions .15 .30 .40
3279 @item @tab @code{VALUE(1)}: @tab The year
3280 @item @tab @code{VALUE(2)}: @tab The month
3281 @item @tab @code{VALUE(3)}: @tab The day of the month
3282 @item @tab @code{VALUE(4)}: @tab Time difference with UTC in minutes
3283 @item @tab @code{VALUE(5)}: @tab The hour of the day
3284 @item @tab @code{VALUE(6)}: @tab The minutes of the hour
3285 @item @tab @code{VALUE(7)}: @tab The seconds of the minute
3286 @item @tab @code{VALUE(8)}: @tab The milliseconds of the second
3289 @item @emph{Standard}:
3290 Fortran 95 and later
3295 @item @emph{Syntax}:
3296 @code{CALL DATE_AND_TIME([DATE, TIME, ZONE, VALUES])}
3298 @item @emph{Arguments}:
3299 @multitable @columnfractions .15 .70
3300 @item @var{DATE} @tab (Optional) The type shall be @code{CHARACTER(LEN=8)}
3301 or larger, and of default kind.
3302 @item @var{TIME} @tab (Optional) The type shall be @code{CHARACTER(LEN=10)}
3303 or larger, and of default kind.
3304 @item @var{ZONE} @tab (Optional) The type shall be @code{CHARACTER(LEN=5)}
3305 or larger, and of default kind.
3306 @item @var{VALUES}@tab (Optional) The type shall be @code{INTEGER(8)}.
3309 @item @emph{Return value}:
3312 @item @emph{Example}:
3314 program test_time_and_date
3315 character(8) :: date
3316 character(10) :: time
3317 character(5) :: zone
3318 integer,dimension(8) :: values
3319 ! using keyword arguments
3320 call date_and_time(date,time,zone,values)
3321 call date_and_time(DATE=date,ZONE=zone)
3322 call date_and_time(TIME=time)
3323 call date_and_time(VALUES=values)
3324 print '(a,2x,a,2x,a)', date, time, zone
3325 print '(8i5))', values
3326 end program test_time_and_date
3329 @item @emph{See also}:
3330 @ref{CPU_TIME}, @ref{SYSTEM_CLOCK}
3336 @section @code{DBLE} --- Double conversion function
3338 @cindex conversion, to real
3341 @item @emph{Description}:
3342 @code{DBLE(A)} Converts @var{A} to double precision real type.
3344 @item @emph{Standard}:
3345 Fortran 77 and later
3350 @item @emph{Syntax}:
3351 @code{RESULT = DBLE(A)}
3353 @item @emph{Arguments}:
3354 @multitable @columnfractions .15 .70
3355 @item @var{A} @tab The type shall be @code{INTEGER}, @code{REAL},
3359 @item @emph{Return value}:
3360 The return value is of type double precision real.
3362 @item @emph{Example}:
3367 complex :: z = (2.3,1.14)
3368 print *, dble(x), dble(i), dble(z)
3369 end program test_dble
3372 @item @emph{See also}:
3379 @section @code{DCMPLX} --- Double complex conversion function
3381 @cindex complex numbers, conversion to
3382 @cindex conversion, to complex
3385 @item @emph{Description}:
3386 @code{DCMPLX(X [,Y])} returns a double complex number where @var{X} is
3387 converted to the real component. If @var{Y} is present it is converted to the
3388 imaginary component. If @var{Y} is not present then the imaginary component is
3389 set to 0.0. If @var{X} is complex then @var{Y} must not be present.
3391 @item @emph{Standard}:
3397 @item @emph{Syntax}:
3398 @code{RESULT = DCMPLX(X [, Y])}
3400 @item @emph{Arguments}:
3401 @multitable @columnfractions .15 .70
3402 @item @var{X} @tab The type may be @code{INTEGER}, @code{REAL},
3404 @item @var{Y} @tab (Optional if @var{X} is not @code{COMPLEX}.) May be
3405 @code{INTEGER} or @code{REAL}.
3408 @item @emph{Return value}:
3409 The return value is of type @code{COMPLEX(8)}
3411 @item @emph{Example}:
3421 print *, dcmplx(x,i)
3422 end program test_dcmplx
3428 @section @code{DIGITS} --- Significant binary digits function
3430 @cindex model representation, significant digits
3433 @item @emph{Description}:
3434 @code{DIGITS(X)} returns the number of significant binary digits of the internal
3435 model representation of @var{X}. For example, on a system using a 32-bit
3436 floating point representation, a default real number would likely return 24.
3438 @item @emph{Standard}:
3439 Fortran 95 and later
3444 @item @emph{Syntax}:
3445 @code{RESULT = DIGITS(X)}
3447 @item @emph{Arguments}:
3448 @multitable @columnfractions .15 .70
3449 @item @var{X} @tab The type may be @code{INTEGER} or @code{REAL}.
3452 @item @emph{Return value}:
3453 The return value is of type @code{INTEGER}.
3455 @item @emph{Example}:
3458 integer :: i = 12345
3464 end program test_digits
3471 @section @code{DIM} --- Positive difference
3475 @cindex positive difference
3478 @item @emph{Description}:
3479 @code{DIM(X,Y)} returns the difference @code{X-Y} if the result is positive;
3480 otherwise returns zero.
3482 @item @emph{Standard}:
3483 Fortran 77 and later
3488 @item @emph{Syntax}:
3489 @code{RESULT = DIM(X, Y)}
3491 @item @emph{Arguments}:
3492 @multitable @columnfractions .15 .70
3493 @item @var{X} @tab The type shall be @code{INTEGER} or @code{REAL}
3494 @item @var{Y} @tab The type shall be the same type and kind as @var{X}.
3497 @item @emph{Return value}:
3498 The return value is of type @code{INTEGER} or @code{REAL}.
3500 @item @emph{Example}:
3506 x = dim(4.345_8, 2.111_8)
3509 end program test_dim
3512 @item @emph{Specific names}:
3513 @multitable @columnfractions .20 .20 .20 .25
3514 @item Name @tab Argument @tab Return type @tab Standard
3515 @item @code{DIM(X,Y)} @tab @code{REAL(4) X, Y} @tab @code{REAL(4)} @tab Fortran 77 and later
3516 @item @code{IDIM(X,Y)} @tab @code{INTEGER(4) X, Y} @tab @code{INTEGER(4)} @tab Fortran 77 and later
3517 @item @code{DDIM(X,Y)} @tab @code{REAL(8) X, Y} @tab @code{REAL(8)} @tab Fortran 77 and later
3524 @section @code{DOT_PRODUCT} --- Dot product function
3525 @fnindex DOT_PRODUCT
3527 @cindex vector product
3528 @cindex product, vector
3531 @item @emph{Description}:
3532 @code{DOT_PRODUCT(VECTOR_A, VECTOR_B)} computes the dot product multiplication
3533 of two vectors @var{VECTOR_A} and @var{VECTOR_B}. The two vectors may be
3534 either numeric or logical and must be arrays of rank one and of equal size. If
3535 the vectors are @code{INTEGER} or @code{REAL}, the result is
3536 @code{SUM(VECTOR_A*VECTOR_B)}. If the vectors are @code{COMPLEX}, the result
3537 is @code{SUM(CONJG(VECTOR_A)*VECTOR_B)}. If the vectors are @code{LOGICAL},
3538 the result is @code{ANY(VECTOR_A .AND. VECTOR_B)}.
3540 @item @emph{Standard}:
3541 Fortran 95 and later
3544 Transformational function
3546 @item @emph{Syntax}:
3547 @code{RESULT = DOT_PRODUCT(VECTOR_A, VECTOR_B)}
3549 @item @emph{Arguments}:
3550 @multitable @columnfractions .15 .70
3551 @item @var{VECTOR_A} @tab The type shall be numeric or @code{LOGICAL}, rank 1.
3552 @item @var{VECTOR_B} @tab The type shall be numeric if @var{VECTOR_A} is of numeric type or @code{LOGICAL} if @var{VECTOR_A} is of type @code{LOGICAL}. @var{VECTOR_B} shall be a rank-one array.
3555 @item @emph{Return value}:
3556 If the arguments are numeric, the return value is a scalar of numeric type,
3557 @code{INTEGER}, @code{REAL}, or @code{COMPLEX}. If the arguments are
3558 @code{LOGICAL}, the return value is @code{.TRUE.} or @code{.FALSE.}.
3560 @item @emph{Example}:
3562 program test_dot_prod
3563 integer, dimension(3) :: a, b
3570 print *, dot_product(a,b)
3571 end program test_dot_prod
3578 @section @code{DPROD} --- Double product function
3580 @cindex product, double-precision
3583 @item @emph{Description}:
3584 @code{DPROD(X,Y)} returns the product @code{X*Y}.
3586 @item @emph{Standard}:
3587 Fortran 77 and later
3592 @item @emph{Syntax}:
3593 @code{RESULT = DPROD(X, Y)}
3595 @item @emph{Arguments}:
3596 @multitable @columnfractions .15 .70
3597 @item @var{X} @tab The type shall be @code{REAL}.
3598 @item @var{Y} @tab The type shall be @code{REAL}.
3601 @item @emph{Return value}:
3602 The return value is of type @code{REAL(8)}.
3604 @item @emph{Example}:
3612 end program test_dprod
3615 @item @emph{Specific names}:
3616 @multitable @columnfractions .20 .20 .20 .25
3617 @item Name @tab Argument @tab Return type @tab Standard
3618 @item @code{DPROD(X,Y)} @tab @code{REAL(4) X, Y} @tab @code{REAL(4)} @tab Fortran 77 and later
3625 @section @code{DREAL} --- Double real part function
3627 @cindex complex numbers, real part
3630 @item @emph{Description}:
3631 @code{DREAL(Z)} returns the real part of complex variable @var{Z}.
3633 @item @emph{Standard}:
3639 @item @emph{Syntax}:
3640 @code{RESULT = DREAL(A)}
3642 @item @emph{Arguments}:
3643 @multitable @columnfractions .15 .70
3644 @item @var{A} @tab The type shall be @code{COMPLEX(8)}.
3647 @item @emph{Return value}:
3648 The return value is of type @code{REAL(8)}.
3650 @item @emph{Example}:
3653 complex(8) :: z = (1.3_8,7.2_8)
3655 end program test_dreal
3658 @item @emph{See also}:
3666 @section @code{DSHIFTL} --- Combined left shift
3668 @cindex left shift, combined
3672 @item @emph{Description}:
3673 @code{DSHIFTL(I, J, SHIFT)} combines bits of @var{I} and @var{J}. The
3674 rightmost @var{SHIFT} bits of the result are the leftmost @var{SHIFT}
3675 bits of @var{J}, and the remaining bits are the rightmost bits of
3678 @item @emph{Standard}:
3679 Fortran 2008 and later
3684 @item @emph{Syntax}:
3685 @code{RESULT = DSHIFTL(I, J, SHIFT)}
3687 @item @emph{Arguments}:
3688 @multitable @columnfractions .15 .70
3689 @item @var{I} @tab Shall be of type @code{INTEGER}.
3690 @item @var{J} @tab Shall be of type @code{INTEGER}, and of the same kind
3692 @item @var{SHIFT} @tab Shall be of type @code{INTEGER}.
3695 @item @emph{Return value}:
3696 The return value has same type and kind as @var{I}.
3698 @item @emph{See also}:
3706 @section @code{DSHIFTR} --- Combined right shift
3708 @cindex right shift, combined
3709 @cindex shift, right
3712 @item @emph{Description}:
3713 @code{DSHIFTR(I, J, SHIFT)} combines bits of @var{I} and @var{J}. The
3714 leftmost @var{SHIFT} bits of the result are the rightmost @var{SHIFT}
3715 bits of @var{I}, and the remaining bits are the leftmost bits of
3718 @item @emph{Standard}:
3719 Fortran 2008 and later
3724 @item @emph{Syntax}:
3725 @code{RESULT = DSHIFTR(I, J, SHIFT)}
3727 @item @emph{Arguments}:
3728 @multitable @columnfractions .15 .70
3729 @item @var{I} @tab Shall be of type @code{INTEGER}.
3730 @item @var{J} @tab Shall be of type @code{INTEGER}, and of the same kind
3732 @item @var{SHIFT} @tab Shall be of type @code{INTEGER}.
3735 @item @emph{Return value}:
3736 The return value has same type and kind as @var{I}.
3738 @item @emph{See also}:
3746 @section @code{DTIME} --- Execution time subroutine (or function)
3748 @cindex time, elapsed
3749 @cindex elapsed time
3752 @item @emph{Description}:
3753 @code{DTIME(VALUES, TIME)} initially returns the number of seconds of runtime
3754 since the start of the process's execution in @var{TIME}. @var{VALUES}
3755 returns the user and system components of this time in @code{VALUES(1)} and
3756 @code{VALUES(2)} respectively. @var{TIME} is equal to @code{VALUES(1) +
3759 Subsequent invocations of @code{DTIME} return values accumulated since the
3760 previous invocation.
3762 On some systems, the underlying timings are represented using types with
3763 sufficiently small limits that overflows (wrap around) are possible, such as
3764 32-bit types. Therefore, the values returned by this intrinsic might be, or
3765 become, negative, or numerically less than previous values, during a single
3766 run of the compiled program.
3768 Please note, that this implementation is thread safe if used within OpenMP
3769 directives, i.e., its state will be consistent while called from multiple
3770 threads. However, if @code{DTIME} is called from multiple threads, the result
3771 is still the time since the last invocation. This may not give the intended
3772 results. If possible, use @code{CPU_TIME} instead.
3774 This intrinsic is provided in both subroutine and function forms; however,
3775 only one form can be used in any given program unit.
3777 @var{VALUES} and @var{TIME} are @code{INTENT(OUT)} and provide the following:
3779 @multitable @columnfractions .15 .30 .40
3780 @item @tab @code{VALUES(1)}: @tab User time in seconds.
3781 @item @tab @code{VALUES(2)}: @tab System time in seconds.
3782 @item @tab @code{TIME}: @tab Run time since start in seconds.
3785 @item @emph{Standard}:
3789 Subroutine, function
3791 @item @emph{Syntax}:
3792 @multitable @columnfractions .80
3793 @item @code{CALL DTIME(VALUES, TIME)}.
3794 @item @code{TIME = DTIME(VALUES)}, (not recommended).
3797 @item @emph{Arguments}:
3798 @multitable @columnfractions .15 .70
3799 @item @var{VALUES}@tab The type shall be @code{REAL(4), DIMENSION(2)}.
3800 @item @var{TIME}@tab The type shall be @code{REAL(4)}.
3803 @item @emph{Return value}:
3804 Elapsed time in seconds since the last invocation or since the start of program
3805 execution if not called before.
3807 @item @emph{Example}:
3811 real, dimension(2) :: tarray
3813 call dtime(tarray, result)
3817 do i=1,100000000 ! Just a delay
3820 call dtime(tarray, result)
3824 end program test_dtime
3827 @item @emph{See also}:
3835 @section @code{EOSHIFT} --- End-off shift elements of an array
3837 @cindex array, shift
3840 @item @emph{Description}:
3841 @code{EOSHIFT(ARRAY, SHIFT[, BOUNDARY, DIM])} performs an end-off shift on
3842 elements of @var{ARRAY} along the dimension of @var{DIM}. If @var{DIM} is
3843 omitted it is taken to be @code{1}. @var{DIM} is a scalar of type
3844 @code{INTEGER} in the range of @math{1 \leq DIM \leq n)} where @math{n} is the
3845 rank of @var{ARRAY}. If the rank of @var{ARRAY} is one, then all elements of
3846 @var{ARRAY} are shifted by @var{SHIFT} places. If rank is greater than one,
3847 then all complete rank one sections of @var{ARRAY} along the given dimension are
3848 shifted. Elements shifted out one end of each rank one section are dropped. If
3849 @var{BOUNDARY} is present then the corresponding value of from @var{BOUNDARY}
3850 is copied back in the other end. If @var{BOUNDARY} is not present then the
3851 following are copied in depending on the type of @var{ARRAY}.
3853 @multitable @columnfractions .15 .80
3854 @item @emph{Array Type} @tab @emph{Boundary Value}
3855 @item Numeric @tab 0 of the type and kind of @var{ARRAY}.
3856 @item Logical @tab @code{.FALSE.}.
3857 @item Character(@var{len}) @tab @var{len} blanks.
3860 @item @emph{Standard}:
3861 Fortran 95 and later
3864 Transformational function
3866 @item @emph{Syntax}:
3867 @code{RESULT = EOSHIFT(ARRAY, SHIFT [, BOUNDARY, DIM])}
3869 @item @emph{Arguments}:
3870 @multitable @columnfractions .15 .70
3871 @item @var{ARRAY} @tab May be any type, not scalar.
3872 @item @var{SHIFT} @tab The type shall be @code{INTEGER}.
3873 @item @var{BOUNDARY} @tab Same type as @var{ARRAY}.
3874 @item @var{DIM} @tab The type shall be @code{INTEGER}.
3877 @item @emph{Return value}:
3878 Returns an array of same type and rank as the @var{ARRAY} argument.
3880 @item @emph{Example}:
3882 program test_eoshift
3883 integer, dimension(3,3) :: a
3884 a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /))
3885 print '(3i3)', a(1,:)
3886 print '(3i3)', a(2,:)
3887 print '(3i3)', a(3,:)
3888 a = EOSHIFT(a, SHIFT=(/1, 2, 1/), BOUNDARY=-5, DIM=2)
3890 print '(3i3)', a(1,:)
3891 print '(3i3)', a(2,:)
3892 print '(3i3)', a(3,:)
3893 end program test_eoshift
3900 @section @code{EPSILON} --- Epsilon function
3902 @cindex model representation, epsilon
3905 @item @emph{Description}:
3906 @code{EPSILON(X)} returns the smallest number @var{E} of the same kind
3907 as @var{X} such that @math{1 + E > 1}.
3909 @item @emph{Standard}:
3910 Fortran 95 and later
3915 @item @emph{Syntax}:
3916 @code{RESULT = EPSILON(X)}
3918 @item @emph{Arguments}:
3919 @multitable @columnfractions .15 .70
3920 @item @var{X} @tab The type shall be @code{REAL}.
3923 @item @emph{Return value}:
3924 The return value is of same type as the argument.
3926 @item @emph{Example}:
3928 program test_epsilon
3933 end program test_epsilon
3940 @section @code{ERF} --- Error function
3942 @cindex error function
3945 @item @emph{Description}:
3946 @code{ERF(X)} computes the error function of @var{X}.
3948 @item @emph{Standard}:
3949 Fortran 2008 and later
3954 @item @emph{Syntax}:
3955 @code{RESULT = ERF(X)}
3957 @item @emph{Arguments}:
3958 @multitable @columnfractions .15 .70
3959 @item @var{X} @tab The type shall be @code{REAL}.
3962 @item @emph{Return value}:
3963 The return value is of type @code{REAL}, of the same kind as
3964 @var{X} and lies in the range @math{-1 \leq erf (x) \leq 1 }.
3966 @item @emph{Example}:
3969 real(8) :: x = 0.17_8
3971 end program test_erf
3974 @item @emph{Specific names}:
3975 @multitable @columnfractions .20 .20 .20 .25
3976 @item Name @tab Argument @tab Return type @tab Standard
3977 @item @code{DERF(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU extension
3984 @section @code{ERFC} --- Error function
3986 @cindex error function, complementary
3989 @item @emph{Description}:
3990 @code{ERFC(X)} computes the complementary error function of @var{X}.
3992 @item @emph{Standard}:
3993 Fortran 2008 and later
3998 @item @emph{Syntax}:
3999 @code{RESULT = ERFC(X)}
4001 @item @emph{Arguments}:
4002 @multitable @columnfractions .15 .70
4003 @item @var{X} @tab The type shall be @code{REAL}.
4006 @item @emph{Return value}:
4007 The return value is of type @code{REAL} and of the same kind as @var{X}.
4008 It lies in the range @math{ 0 \leq erfc (x) \leq 2 }.
4010 @item @emph{Example}:
4013 real(8) :: x = 0.17_8
4015 end program test_erfc
4018 @item @emph{Specific names}:
4019 @multitable @columnfractions .20 .20 .20 .25
4020 @item Name @tab Argument @tab Return type @tab Standard
4021 @item @code{DERFC(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU extension
4028 @section @code{ERFC_SCALED} --- Error function
4029 @fnindex ERFC_SCALED
4030 @cindex error function, complementary, exponentially-scaled
4033 @item @emph{Description}:
4034 @code{ERFC_SCALED(X)} computes the exponentially-scaled complementary
4035 error function of @var{X}.
4037 @item @emph{Standard}:
4038 Fortran 2008 and later
4043 @item @emph{Syntax}:
4044 @code{RESULT = ERFC_SCALED(X)}
4046 @item @emph{Arguments}:
4047 @multitable @columnfractions .15 .70
4048 @item @var{X} @tab The type shall be @code{REAL}.
4051 @item @emph{Return value}:
4052 The return value is of type @code{REAL} and of the same kind as @var{X}.
4054 @item @emph{Example}:
4056 program test_erfc_scaled
4057 real(8) :: x = 0.17_8
4059 end program test_erfc_scaled
4066 @section @code{ETIME} --- Execution time subroutine (or function)
4068 @cindex time, elapsed
4071 @item @emph{Description}:
4072 @code{ETIME(VALUES, TIME)} returns the number of seconds of runtime
4073 since the start of the process's execution in @var{TIME}. @var{VALUES}
4074 returns the user and system components of this time in @code{VALUES(1)} and
4075 @code{VALUES(2)} respectively. @var{TIME} is equal to @code{VALUES(1) + VALUES(2)}.
4077 On some systems, the underlying timings are represented using types with
4078 sufficiently small limits that overflows (wrap around) are possible, such as
4079 32-bit types. Therefore, the values returned by this intrinsic might be, or
4080 become, negative, or numerically less than previous values, during a single
4081 run of the compiled program.
4083 This intrinsic is provided in both subroutine and function forms; however,
4084 only one form can be used in any given program unit.
4086 @var{VALUES} and @var{TIME} are @code{INTENT(OUT)} and provide the following:
4088 @multitable @columnfractions .15 .30 .60
4089 @item @tab @code{VALUES(1)}: @tab User time in seconds.
4090 @item @tab @code{VALUES(2)}: @tab System time in seconds.
4091 @item @tab @code{TIME}: @tab Run time since start in seconds.
4094 @item @emph{Standard}:
4098 Subroutine, function
4100 @item @emph{Syntax}:
4101 @multitable @columnfractions .80
4102 @item @code{CALL ETIME(VALUES, TIME)}.
4103 @item @code{TIME = ETIME(VALUES)}, (not recommended).
4106 @item @emph{Arguments}:
4107 @multitable @columnfractions .15 .70
4108 @item @var{VALUES}@tab The type shall be @code{REAL(4), DIMENSION(2)}.
4109 @item @var{TIME}@tab The type shall be @code{REAL(4)}.
4112 @item @emph{Return value}:
4113 Elapsed time in seconds since the start of program execution.
4115 @item @emph{Example}:
4119 real, dimension(2) :: tarray
4121 call ETIME(tarray, result)
4125 do i=1,100000000 ! Just a delay
4128 call ETIME(tarray, result)
4132 end program test_etime
4135 @item @emph{See also}:
4142 @node EXECUTE_COMMAND_LINE
4143 @section @code{EXECUTE_COMMAND_LINE} --- Execute a shell command
4144 @fnindex EXECUTE_COMMAND_LINE
4145 @cindex system, system call
4146 @cindex command line
4149 @item @emph{Description}:
4150 @code{EXECUTE_COMMAND_LINE} runs a shell command, synchronously or
4153 The @code{COMMAND} argument is passed to the shell and executed, using
4154 the C library's @code{system()} call. (The shell is @code{sh} on Unix
4155 systems, and @code{cmd.exe} on Windows.) If @code{WAIT} is present and
4156 has the value false, the execution of the command is asynchronous if the
4157 system supports it; otherwise, the command is executed synchronously.
4159 The three last arguments allow the user to get status information. After
4160 synchronous execution, @code{EXITSTAT} contains the integer exit code of
4161 the command, as returned by @code{system}. @code{CMDSTAT} is set to zero
4162 if the command line was executed (whatever its exit status was).
4163 @code{CMDMSG} is assigned an error message if an error has occurred.
4166 @item @emph{Standard}:
4167 Fortran 2008 and later
4172 @item @emph{Syntax}:
4173 @code{CALL EXECUTE_COMMAND_LINE(COMMAND [, WAIT, EXITSTAT, CMDSTAT, CMDMSG ])}
4175 @item @emph{Arguments}:
4176 @multitable @columnfractions .15 .70
4177 @item @var{COMMAND} @tab Shall be a default @code{CHARACTER} scalar.
4178 @item @var{WAIT} @tab (Optional) Shall be a default @code{LOGICAL} scalar.
4179 @item @var{EXITSTAT} @tab (Optional) Shall be an @code{INTEGER} of the
4181 @item @var{CMDSTAT} @tab (Optional) Shall be an @code{INTEGER} of the
4183 @item @var{CMDMSG} @tab (Optional) Shall be an @code{CHARACTER} scalar of the
4187 @item @emph{Example}:
4192 call execute_command_line ("external_prog.exe", exitstat=i)
4193 print *, "Exit status of external_prog.exe was ", i
4195 call execute_command_line ("reindex_files.exe", wait=.false.)
4196 print *, "Now reindexing files in the background"
4198 end program test_exec
4204 Because this intrinsic is implemented in terms of the @code{system()}
4205 function call, its behavior with respect to signaling is processor
4206 dependent. In particular, on POSIX-compliant systems, the SIGINT and
4207 SIGQUIT signals will be ignored, and the SIGCHLD will be blocked. As
4208 such, if the parent process is terminated, the child process might not be
4209 terminated alongside.
4212 @item @emph{See also}:
4219 @section @code{EXIT} --- Exit the program with status.
4221 @cindex program termination
4222 @cindex terminate program
4225 @item @emph{Description}:
4226 @code{EXIT} causes immediate termination of the program with status. If status
4227 is omitted it returns the canonical @emph{success} for the system. All Fortran
4228 I/O units are closed.
4230 @item @emph{Standard}:
4236 @item @emph{Syntax}:
4237 @code{CALL EXIT([STATUS])}
4239 @item @emph{Arguments}:
4240 @multitable @columnfractions .15 .70
4241 @item @var{STATUS} @tab Shall be an @code{INTEGER} of the default kind.
4244 @item @emph{Return value}:
4245 @code{STATUS} is passed to the parent process on exit.
4247 @item @emph{Example}:
4250 integer :: STATUS = 0
4251 print *, 'This program is going to exit.'
4253 end program test_exit
4256 @item @emph{See also}:
4257 @ref{ABORT}, @ref{KILL}
4263 @section @code{EXP} --- Exponential function
4269 @cindex exponential function
4270 @cindex logarithmic function, inverse
4273 @item @emph{Description}:
4274 @code{EXP(X)} computes the base @math{e} exponential of @var{X}.
4276 @item @emph{Standard}:
4277 Fortran 77 and later, has overloads that are GNU extensions
4282 @item @emph{Syntax}:
4283 @code{RESULT = EXP(X)}
4285 @item @emph{Arguments}:
4286 @multitable @columnfractions .15 .70
4287 @item @var{X} @tab The type shall be @code{REAL} or
4291 @item @emph{Return value}:
4292 The return value has same type and kind as @var{X}.
4294 @item @emph{Example}:
4299 end program test_exp
4302 @item @emph{Specific names}:
4303 @multitable @columnfractions .20 .20 .20 .25
4304 @item Name @tab Argument @tab Return type @tab Standard
4305 @item @code{EXP(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 77 and later
4306 @item @code{DEXP(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 77 and later
4307 @item @code{CEXP(X)} @tab @code{COMPLEX(4) X} @tab @code{COMPLEX(4)} @tab Fortran 77 and later
4308 @item @code{ZEXP(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
4309 @item @code{CDEXP(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
4316 @section @code{EXPONENT} --- Exponent function
4318 @cindex real number, exponent
4319 @cindex floating point, exponent
4322 @item @emph{Description}:
4323 @code{EXPONENT(X)} returns the value of the exponent part of @var{X}. If @var{X}
4324 is zero the value returned is zero.
4326 @item @emph{Standard}:
4327 Fortran 95 and later
4332 @item @emph{Syntax}:
4333 @code{RESULT = EXPONENT(X)}
4335 @item @emph{Arguments}:
4336 @multitable @columnfractions .15 .70
4337 @item @var{X} @tab The type shall be @code{REAL}.
4340 @item @emph{Return value}:
4341 The return value is of type default @code{INTEGER}.
4343 @item @emph{Example}:
4345 program test_exponent
4350 print *, exponent(0.0)
4351 end program test_exponent
4357 @node EXTENDS_TYPE_OF
4358 @section @code{EXTENDS_TYPE_OF} --- Query dynamic type for extension
4359 @fnindex EXTENDS_TYPE_OF
4362 @item @emph{Description}:
4363 Query dynamic type for extension.
4365 @item @emph{Standard}:
4366 Fortran 2003 and later
4371 @item @emph{Syntax}:
4372 @code{RESULT = EXTENDS_TYPE_OF(A, MOLD)}
4374 @item @emph{Arguments}:
4375 @multitable @columnfractions .15 .70
4376 @item @var{A} @tab Shall be an object of extensible declared type or
4377 unlimited polymorphic.
4378 @item @var{MOLD} @tab Shall be an object of extensible declared type or
4379 unlimited polymorphic.
4382 @item @emph{Return value}:
4383 The return value is a scalar of type default logical. It is true if and only if
4384 the dynamic type of A is an extension type of the dynamic type of MOLD.
4387 @item @emph{See also}:
4394 @section @code{FDATE} --- Get the current time as a string
4396 @cindex time, current
4397 @cindex current time
4398 @cindex date, current
4399 @cindex current date
4402 @item @emph{Description}:
4403 @code{FDATE(DATE)} returns the current date (using the same format as
4404 @code{CTIME}) in @var{DATE}. It is equivalent to @code{CALL CTIME(DATE,
4407 This intrinsic is provided in both subroutine and function forms; however,
4408 only one form can be used in any given program unit.
4410 @var{DATE} is an @code{INTENT(OUT)} @code{CHARACTER} variable of the
4413 @item @emph{Standard}:
4417 Subroutine, function
4419 @item @emph{Syntax}:
4420 @multitable @columnfractions .80
4421 @item @code{CALL FDATE(DATE)}.
4422 @item @code{DATE = FDATE()}, (not recommended).
4425 @item @emph{Arguments}:
4426 @multitable @columnfractions .15 .70
4427 @item @var{DATE}@tab The type shall be of type @code{CHARACTER} of the
4431 @item @emph{Return value}:
4432 The current date as a string.
4434 @item @emph{Example}:
4438 character(len=30) :: date
4440 print *, 'Program started on ', date
4441 do i = 1, 100000000 ! Just a delay
4445 print *, 'Program ended on ', date
4446 end program test_fdate
4453 @section @code{FGET} --- Read a single character in stream mode from stdin
4455 @cindex read character, stream mode
4456 @cindex stream mode, read character
4457 @cindex file operation, read character
4460 @item @emph{Description}:
4461 Read a single character in stream mode from stdin by bypassing normal
4462 formatted output. Stream I/O should not be mixed with normal record-oriented
4463 (formatted or unformatted) I/O on the same unit; the results are unpredictable.
4465 This intrinsic is provided in both subroutine and function forms; however,
4466 only one form can be used in any given program unit.
4468 Note that the @code{FGET} intrinsic is provided for backwards compatibility with
4469 @command{g77}. GNU Fortran provides the Fortran 2003 Stream facility.
4470 Programmers should consider the use of new stream IO feature in new code
4471 for future portability. See also @ref{Fortran 2003 status}.
4473 @item @emph{Standard}:
4477 Subroutine, function
4479 @item @emph{Syntax}:
4480 @multitable @columnfractions .80
4481 @item @code{CALL FGET(C [, STATUS])}
4482 @item @code{STATUS = FGET(C)}
4485 @item @emph{Arguments}:
4486 @multitable @columnfractions .15 .70
4487 @item @var{C} @tab The type shall be @code{CHARACTER} and of default
4489 @item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER}.
4490 Returns 0 on success, -1 on end-of-file, and a system specific positive
4491 error code otherwise.
4494 @item @emph{Example}:
4497 INTEGER, PARAMETER :: strlen = 100
4498 INTEGER :: status, i = 1
4499 CHARACTER(len=strlen) :: str = ""
4501 WRITE (*,*) 'Enter text:'
4503 CALL fget(str(i:i), status)
4504 if (status /= 0 .OR. i > strlen) exit
4507 WRITE (*,*) TRIM(str)
4511 @item @emph{See also}:
4512 @ref{FGETC}, @ref{FPUT}, @ref{FPUTC}
4518 @section @code{FGETC} --- Read a single character in stream mode
4520 @cindex read character, stream mode
4521 @cindex stream mode, read character
4522 @cindex file operation, read character
4525 @item @emph{Description}:
4526 Read a single character in stream mode by bypassing normal formatted output.
4527 Stream I/O should not be mixed with normal record-oriented (formatted or
4528 unformatted) I/O on the same unit; the results are unpredictable.
4530 This intrinsic is provided in both subroutine and function forms; however,
4531 only one form can be used in any given program unit.
4533 Note that the @code{FGET} intrinsic is provided for backwards compatibility
4534 with @command{g77}. GNU Fortran provides the Fortran 2003 Stream facility.
4535 Programmers should consider the use of new stream IO feature in new code
4536 for future portability. See also @ref{Fortran 2003 status}.
4538 @item @emph{Standard}:
4542 Subroutine, function
4544 @item @emph{Syntax}:
4545 @multitable @columnfractions .80
4546 @item @code{CALL FGETC(UNIT, C [, STATUS])}
4547 @item @code{STATUS = FGETC(UNIT, C)}
4550 @item @emph{Arguments}:
4551 @multitable @columnfractions .15 .70
4552 @item @var{UNIT} @tab The type shall be @code{INTEGER}.
4553 @item @var{C} @tab The type shall be @code{CHARACTER} and of default
4555 @item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER}.
4556 Returns 0 on success, -1 on end-of-file and a system specific positive
4557 error code otherwise.
4560 @item @emph{Example}:
4563 INTEGER :: fd = 42, status
4566 OPEN(UNIT=fd, FILE="/etc/passwd", ACTION="READ", STATUS = "OLD")
4568 CALL fgetc(fd, c, status)
4569 IF (status /= 0) EXIT
4576 @item @emph{See also}:
4577 @ref{FGET}, @ref{FPUT}, @ref{FPUTC}
4583 @section @code{FLOOR} --- Integer floor function
4586 @cindex rounding, floor
4589 @item @emph{Description}:
4590 @code{FLOOR(A)} returns the greatest integer less than or equal to @var{X}.
4592 @item @emph{Standard}:
4593 Fortran 95 and later
4598 @item @emph{Syntax}:
4599 @code{RESULT = FLOOR(A [, KIND])}
4601 @item @emph{Arguments}:
4602 @multitable @columnfractions .15 .70
4603 @item @var{A} @tab The type shall be @code{REAL}.
4604 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
4605 expression indicating the kind parameter of the result.
4608 @item @emph{Return value}:
4609 The return value is of type @code{INTEGER(KIND)} if @var{KIND} is present
4610 and of default-kind @code{INTEGER} otherwise.
4612 @item @emph{Example}:
4617 print *, floor(x) ! returns 63
4618 print *, floor(y) ! returns -64
4619 end program test_floor
4622 @item @emph{See also}:
4623 @ref{CEILING}, @ref{NINT}
4630 @section @code{FLUSH} --- Flush I/O unit(s)
4632 @cindex file operation, flush
4635 @item @emph{Description}:
4636 Flushes Fortran unit(s) currently open for output. Without the optional
4637 argument, all units are flushed, otherwise just the unit specified.
4639 @item @emph{Standard}:
4645 @item @emph{Syntax}:
4646 @code{CALL FLUSH(UNIT)}
4648 @item @emph{Arguments}:
4649 @multitable @columnfractions .15 .70
4650 @item @var{UNIT} @tab (Optional) The type shall be @code{INTEGER}.
4654 Beginning with the Fortran 2003 standard, there is a @code{FLUSH}
4655 statement that should be preferred over the @code{FLUSH} intrinsic.
4657 The @code{FLUSH} intrinsic and the Fortran 2003 @code{FLUSH} statement
4658 have identical effect: they flush the runtime library's I/O buffer so
4659 that the data becomes visible to other processes. This does not guarantee
4660 that the data is committed to disk.
4662 On POSIX systems, you can request that all data is transferred to the
4663 storage device by calling the @code{fsync} function, with the POSIX file
4664 descriptor of the I/O unit as argument (retrieved with GNU intrinsic
4665 @code{FNUM}). The following example shows how:
4668 ! Declare the interface for POSIX fsync function
4670 function fsync (fd) bind(c,name="fsync")
4671 use iso_c_binding, only: c_int
4672 integer(c_int), value :: fd
4673 integer(c_int) :: fsync
4677 ! Variable declaration
4681 open (10,file="foo")
4684 ! Perform I/O on unit 10
4689 ret = fsync(fnum(10))
4691 ! Handle possible error
4692 if (ret /= 0) stop "Error calling FSYNC"
4700 @section @code{FNUM} --- File number function
4702 @cindex file operation, file number
4705 @item @emph{Description}:
4706 @code{FNUM(UNIT)} returns the POSIX file descriptor number corresponding to the
4707 open Fortran I/O unit @code{UNIT}.
4709 @item @emph{Standard}:
4715 @item @emph{Syntax}:
4716 @code{RESULT = FNUM(UNIT)}
4718 @item @emph{Arguments}:
4719 @multitable @columnfractions .15 .70
4720 @item @var{UNIT} @tab The type shall be @code{INTEGER}.
4723 @item @emph{Return value}:
4724 The return value is of type @code{INTEGER}
4726 @item @emph{Example}:
4730 open (unit=10, status = "scratch")
4734 end program test_fnum
4741 @section @code{FPUT} --- Write a single character in stream mode to stdout
4743 @cindex write character, stream mode
4744 @cindex stream mode, write character
4745 @cindex file operation, write character
4748 @item @emph{Description}:
4749 Write a single character in stream mode to stdout by bypassing normal
4750 formatted output. Stream I/O should not be mixed with normal record-oriented
4751 (formatted or unformatted) I/O on the same unit; the results are unpredictable.
4753 This intrinsic is provided in both subroutine and function forms; however,
4754 only one form can be used in any given program unit.
4756 Note that the @code{FGET} intrinsic is provided for backwards compatibility with
4757 @command{g77}. GNU Fortran provides the Fortran 2003 Stream facility.
4758 Programmers should consider the use of new stream IO feature in new code
4759 for future portability. See also @ref{Fortran 2003 status}.
4761 @item @emph{Standard}:
4765 Subroutine, function
4767 @item @emph{Syntax}:
4768 @multitable @columnfractions .80
4769 @item @code{CALL FPUT(C [, STATUS])}
4770 @item @code{STATUS = FPUT(C)}
4773 @item @emph{Arguments}:
4774 @multitable @columnfractions .15 .70
4775 @item @var{C} @tab The type shall be @code{CHARACTER} and of default
4777 @item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER}.
4778 Returns 0 on success, -1 on end-of-file and a system specific positive
4779 error code otherwise.
4782 @item @emph{Example}:
4785 CHARACTER(len=10) :: str = "gfortran"
4787 DO i = 1, len_trim(str)
4793 @item @emph{See also}:
4794 @ref{FPUTC}, @ref{FGET}, @ref{FGETC}
4800 @section @code{FPUTC} --- Write a single character in stream mode
4802 @cindex write character, stream mode
4803 @cindex stream mode, write character
4804 @cindex file operation, write character
4807 @item @emph{Description}:
4808 Write a single character in stream mode by bypassing normal formatted
4809 output. Stream I/O should not be mixed with normal record-oriented
4810 (formatted or unformatted) I/O on the same unit; the results are unpredictable.
4812 This intrinsic is provided in both subroutine and function forms; however,
4813 only one form can be used in any given program unit.
4815 Note that the @code{FGET} intrinsic is provided for backwards compatibility with
4816 @command{g77}. GNU Fortran provides the Fortran 2003 Stream facility.
4817 Programmers should consider the use of new stream IO feature in new code
4818 for future portability. See also @ref{Fortran 2003 status}.
4820 @item @emph{Standard}:
4824 Subroutine, function
4826 @item @emph{Syntax}:
4827 @multitable @columnfractions .80
4828 @item @code{CALL FPUTC(UNIT, C [, STATUS])}
4829 @item @code{STATUS = FPUTC(UNIT, C)}
4832 @item @emph{Arguments}:
4833 @multitable @columnfractions .15 .70
4834 @item @var{UNIT} @tab The type shall be @code{INTEGER}.
4835 @item @var{C} @tab The type shall be @code{CHARACTER} and of default
4837 @item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER}.
4838 Returns 0 on success, -1 on end-of-file and a system specific positive
4839 error code otherwise.
4842 @item @emph{Example}:
4845 CHARACTER(len=10) :: str = "gfortran"
4846 INTEGER :: fd = 42, i
4848 OPEN(UNIT = fd, FILE = "out", ACTION = "WRITE", STATUS="NEW")
4849 DO i = 1, len_trim(str)
4850 CALL fputc(fd, str(i:i))
4856 @item @emph{See also}:
4857 @ref{FPUT}, @ref{FGET}, @ref{FGETC}
4863 @section @code{FRACTION} --- Fractional part of the model representation
4865 @cindex real number, fraction
4866 @cindex floating point, fraction
4869 @item @emph{Description}:
4870 @code{FRACTION(X)} returns the fractional part of the model
4871 representation of @code{X}.
4873 @item @emph{Standard}:
4874 Fortran 95 and later
4879 @item @emph{Syntax}:
4880 @code{Y = FRACTION(X)}
4882 @item @emph{Arguments}:
4883 @multitable @columnfractions .15 .70
4884 @item @var{X} @tab The type of the argument shall be a @code{REAL}.
4887 @item @emph{Return value}:
4888 The return value is of the same type and kind as the argument.
4889 The fractional part of the model representation of @code{X} is returned;
4890 it is @code{X * RADIX(X)**(-EXPONENT(X))}.
4892 @item @emph{Example}:
4894 program test_fraction
4897 print *, fraction(x), x * radix(x)**(-exponent(x))
4898 end program test_fraction
4906 @section @code{FREE} --- Frees memory
4908 @cindex pointer, cray
4911 @item @emph{Description}:
4912 Frees memory previously allocated by @code{MALLOC()}. The @code{FREE}
4913 intrinsic is an extension intended to be used with Cray pointers, and is
4914 provided in GNU Fortran to allow user to compile legacy code. For
4915 new code using Fortran 95 pointers, the memory de-allocation intrinsic is
4918 @item @emph{Standard}:
4924 @item @emph{Syntax}:
4925 @code{CALL FREE(PTR)}
4927 @item @emph{Arguments}:
4928 @multitable @columnfractions .15 .70
4929 @item @var{PTR} @tab The type shall be @code{INTEGER}. It represents the
4930 location of the memory that should be de-allocated.
4933 @item @emph{Return value}:
4936 @item @emph{Example}:
4937 See @code{MALLOC} for an example.
4939 @item @emph{See also}:
4946 @section @code{FSEEK} --- Low level file positioning subroutine
4948 @cindex file operation, seek
4949 @cindex file operation, position
4952 @item @emph{Description}:
4953 Moves @var{UNIT} to the specified @var{OFFSET}. If @var{WHENCE}
4954 is set to 0, the @var{OFFSET} is taken as an absolute value @code{SEEK_SET},
4955 if set to 1, @var{OFFSET} is taken to be relative to the current position
4956 @code{SEEK_CUR}, and if set to 2 relative to the end of the file @code{SEEK_END}.
4957 On error, @var{STATUS} is set to a nonzero value. If @var{STATUS} the seek
4960 This intrinsic routine is not fully backwards compatible with @command{g77}.
4961 In @command{g77}, the @code{FSEEK} takes a statement label instead of a
4962 @var{STATUS} variable. If FSEEK is used in old code, change
4964 CALL FSEEK(UNIT, OFFSET, WHENCE, *label)
4969 CALL FSEEK(UNIT, OFFSET, WHENCE, status)
4970 IF (status /= 0) GOTO label
4973 Please note that GNU Fortran provides the Fortran 2003 Stream facility.
4974 Programmers should consider the use of new stream IO feature in new code
4975 for future portability. See also @ref{Fortran 2003 status}.
4977 @item @emph{Standard}:
4983 @item @emph{Syntax}:
4984 @code{CALL FSEEK(UNIT, OFFSET, WHENCE[, STATUS])}
4986 @item @emph{Arguments}:
4987 @multitable @columnfractions .15 .70
4988 @item @var{UNIT} @tab Shall be a scalar of type @code{INTEGER}.
4989 @item @var{OFFSET} @tab Shall be a scalar of type @code{INTEGER}.
4990 @item @var{WHENCE} @tab Shall be a scalar of type @code{INTEGER}.
4991 Its value shall be either 0, 1 or 2.
4992 @item @var{STATUS} @tab (Optional) shall be a scalar of type
4996 @item @emph{Example}:
4999 INTEGER, PARAMETER :: SEEK_SET = 0, SEEK_CUR = 1, SEEK_END = 2
5000 INTEGER :: fd, offset, ierr
5006 OPEN(UNIT=fd, FILE="fseek.test")
5007 CALL FSEEK(fd, offset, SEEK_SET, ierr) ! move to OFFSET
5008 print *, FTELL(fd), ierr
5010 CALL FSEEK(fd, 0, SEEK_END, ierr) ! move to end
5011 print *, FTELL(fd), ierr
5013 CALL FSEEK(fd, 0, SEEK_SET, ierr) ! move to beginning
5014 print *, FTELL(fd), ierr
5020 @item @emph{See also}:
5027 @section @code{FSTAT} --- Get file status
5029 @cindex file system, file status
5032 @item @emph{Description}:
5033 @code{FSTAT} is identical to @ref{STAT}, except that information about an
5034 already opened file is obtained.
5036 The elements in @code{VALUES} are the same as described by @ref{STAT}.
5038 This intrinsic is provided in both subroutine and function forms; however,
5039 only one form can be used in any given program unit.
5041 @item @emph{Standard}:
5045 Subroutine, function
5047 @item @emph{Syntax}:
5048 @multitable @columnfractions .80
5049 @item @code{CALL FSTAT(UNIT, VALUES [, STATUS])}
5050 @item @code{STATUS = FSTAT(UNIT, VALUES)}
5053 @item @emph{Arguments}:
5054 @multitable @columnfractions .15 .70
5055 @item @var{UNIT} @tab An open I/O unit number of type @code{INTEGER}.
5056 @item @var{VALUES} @tab The type shall be @code{INTEGER(4), DIMENSION(13)}.
5057 @item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER(4)}. Returns 0
5058 on success and a system specific error code otherwise.
5061 @item @emph{Example}:
5062 See @ref{STAT} for an example.
5064 @item @emph{See also}:
5065 To stat a link: @ref{LSTAT}, to stat a file: @ref{STAT}
5071 @section @code{FTELL} --- Current stream position
5073 @cindex file operation, position
5076 @item @emph{Description}:
5077 Retrieves the current position within an open file.
5079 This intrinsic is provided in both subroutine and function forms; however,
5080 only one form can be used in any given program unit.
5082 @item @emph{Standard}:
5086 Subroutine, function
5088 @item @emph{Syntax}:
5089 @multitable @columnfractions .80
5090 @item @code{CALL FTELL(UNIT, OFFSET)}
5091 @item @code{OFFSET = FTELL(UNIT)}
5094 @item @emph{Arguments}:
5095 @multitable @columnfractions .15 .70
5096 @item @var{OFFSET} @tab Shall of type @code{INTEGER}.
5097 @item @var{UNIT} @tab Shall of type @code{INTEGER}.
5100 @item @emph{Return value}:
5101 In either syntax, @var{OFFSET} is set to the current offset of unit
5102 number @var{UNIT}, or to @math{-1} if the unit is not currently open.
5104 @item @emph{Example}:
5108 OPEN(10, FILE="temp.dat")
5114 @item @emph{See also}:
5121 @section @code{GAMMA} --- Gamma function
5124 @cindex Gamma function
5125 @cindex Factorial function
5128 @item @emph{Description}:
5129 @code{GAMMA(X)} computes Gamma (@math{\Gamma}) of @var{X}. For positive,
5130 integer values of @var{X} the Gamma function simplifies to the factorial
5131 function @math{\Gamma(x)=(x-1)!}.
5135 \Gamma(x) = \int_0^\infty t^{x-1}{\rm e}^{-t}\,{\rm d}t
5139 @item @emph{Standard}:
5140 Fortran 2008 and later
5145 @item @emph{Syntax}:
5148 @item @emph{Arguments}:
5149 @multitable @columnfractions .15 .70
5150 @item @var{X} @tab Shall be of type @code{REAL} and neither zero
5151 nor a negative integer.
5154 @item @emph{Return value}:
5155 The return value is of type @code{REAL} of the same kind as @var{X}.
5157 @item @emph{Example}:
5161 x = gamma(x) ! returns 1.0
5162 end program test_gamma
5165 @item @emph{Specific names}:
5166 @multitable @columnfractions .20 .20 .20 .25
5167 @item Name @tab Argument @tab Return type @tab Standard
5168 @item @code{GAMMA(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab GNU Extension
5169 @item @code{DGAMMA(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU Extension
5172 @item @emph{See also}:
5173 Logarithm of the Gamma function: @ref{LOG_GAMMA}
5180 @section @code{GERROR} --- Get last system error message
5182 @cindex system, error handling
5185 @item @emph{Description}:
5186 Returns the system error message corresponding to the last system error.
5187 This resembles the functionality of @code{strerror(3)} in C.
5189 @item @emph{Standard}:
5195 @item @emph{Syntax}:
5196 @code{CALL GERROR(RESULT)}
5198 @item @emph{Arguments}:
5199 @multitable @columnfractions .15 .70
5200 @item @var{RESULT} @tab Shall of type @code{CHARACTER} and of default
5203 @item @emph{Example}:
5206 CHARACTER(len=100) :: msg
5212 @item @emph{See also}:
5213 @ref{IERRNO}, @ref{PERROR}
5219 @section @code{GETARG} --- Get command line arguments
5221 @cindex command-line arguments
5222 @cindex arguments, to program
5225 @item @emph{Description}:
5226 Retrieve the @var{POS}-th argument that was passed on the
5227 command line when the containing program was invoked.
5229 This intrinsic routine is provided for backwards compatibility with
5230 GNU Fortran 77. In new code, programmers should consider the use of
5231 the @ref{GET_COMMAND_ARGUMENT} intrinsic defined by the Fortran 2003
5234 @item @emph{Standard}:
5240 @item @emph{Syntax}:
5241 @code{CALL GETARG(POS, VALUE)}
5243 @item @emph{Arguments}:
5244 @multitable @columnfractions .15 .70
5245 @item @var{POS} @tab Shall be of type @code{INTEGER} and not wider than
5246 the default integer kind; @math{@var{POS} \geq 0}
5247 @item @var{VALUE} @tab Shall be of type @code{CHARACTER} and of default
5249 @item @var{VALUE} @tab Shall be of type @code{CHARACTER}.
5252 @item @emph{Return value}:
5253 After @code{GETARG} returns, the @var{VALUE} argument holds the
5254 @var{POS}th command line argument. If @var{VALUE} can not hold the
5255 argument, it is truncated to fit the length of @var{VALUE}. If there are
5256 less than @var{POS} arguments specified at the command line, @var{VALUE}
5257 will be filled with blanks. If @math{@var{POS} = 0}, @var{VALUE} is set
5258 to the name of the program (on systems that support this feature).
5260 @item @emph{Example}:
5264 CHARACTER(len=32) :: arg
5273 @item @emph{See also}:
5274 GNU Fortran 77 compatibility function: @ref{IARGC}
5276 Fortran 2003 functions and subroutines: @ref{GET_COMMAND},
5277 @ref{GET_COMMAND_ARGUMENT}, @ref{COMMAND_ARGUMENT_COUNT}
5283 @section @code{GET_COMMAND} --- Get the entire command line
5284 @fnindex GET_COMMAND
5285 @cindex command-line arguments
5286 @cindex arguments, to program
5289 @item @emph{Description}:
5290 Retrieve the entire command line that was used to invoke the program.
5292 @item @emph{Standard}:
5293 Fortran 2003 and later
5298 @item @emph{Syntax}:
5299 @code{CALL GET_COMMAND([COMMAND, LENGTH, STATUS])}
5301 @item @emph{Arguments}:
5302 @multitable @columnfractions .15 .70
5303 @item @var{COMMAND} @tab (Optional) shall be of type @code{CHARACTER} and
5305 @item @var{LENGTH} @tab (Optional) Shall be of type @code{INTEGER} and of
5307 @item @var{STATUS} @tab (Optional) Shall be of type @code{INTEGER} and of
5311 @item @emph{Return value}:
5312 If @var{COMMAND} is present, stores the entire command line that was used
5313 to invoke the program in @var{COMMAND}. If @var{LENGTH} is present, it is
5314 assigned the length of the command line. If @var{STATUS} is present, it
5315 is assigned 0 upon success of the command, -1 if @var{COMMAND} is too
5316 short to store the command line, or a positive value in case of an error.
5318 @item @emph{Example}:
5320 PROGRAM test_get_command
5321 CHARACTER(len=255) :: cmd
5322 CALL get_command(cmd)
5323 WRITE (*,*) TRIM(cmd)
5327 @item @emph{See also}:
5328 @ref{GET_COMMAND_ARGUMENT}, @ref{COMMAND_ARGUMENT_COUNT}
5333 @node GET_COMMAND_ARGUMENT
5334 @section @code{GET_COMMAND_ARGUMENT} --- Get command line arguments
5335 @fnindex GET_COMMAND_ARGUMENT
5336 @cindex command-line arguments
5337 @cindex arguments, to program
5340 @item @emph{Description}:
5341 Retrieve the @var{NUMBER}-th argument that was passed on the
5342 command line when the containing program was invoked.
5344 @item @emph{Standard}:
5345 Fortran 2003 and later
5350 @item @emph{Syntax}:
5351 @code{CALL GET_COMMAND_ARGUMENT(NUMBER [, VALUE, LENGTH, STATUS])}
5353 @item @emph{Arguments}:
5354 @multitable @columnfractions .15 .70
5355 @item @var{NUMBER} @tab Shall be a scalar of type @code{INTEGER} and of
5356 default kind, @math{@var{NUMBER} \geq 0}
5357 @item @var{VALUE} @tab Shall be a scalar of type @code{CHARACTER}
5358 and of default kind.
5359 @item @var{LENGTH} @tab (Option) Shall be a scalar of type @code{INTEGER}
5360 and of default kind.
5361 @item @var{STATUS} @tab (Option) Shall be a scalar of type @code{INTEGER}
5362 and of default kind.
5365 @item @emph{Return value}:
5366 After @code{GET_COMMAND_ARGUMENT} returns, the @var{VALUE} argument holds the
5367 @var{NUMBER}-th command line argument. If @var{VALUE} can not hold the argument, it is
5368 truncated to fit the length of @var{VALUE}. If there are less than @var{NUMBER}
5369 arguments specified at the command line, @var{VALUE} will be filled with blanks.
5370 If @math{@var{NUMBER} = 0}, @var{VALUE} is set to the name of the program (on
5371 systems that support this feature). The @var{LENGTH} argument contains the
5372 length of the @var{NUMBER}-th command line argument. If the argument retrieval
5373 fails, @var{STATUS} is a positive number; if @var{VALUE} contains a truncated
5374 command line argument, @var{STATUS} is -1; and otherwise the @var{STATUS} is
5377 @item @emph{Example}:
5379 PROGRAM test_get_command_argument
5381 CHARACTER(len=32) :: arg
5385 CALL get_command_argument(i, arg)
5386 IF (LEN_TRIM(arg) == 0) EXIT
5388 WRITE (*,*) TRIM(arg)
5394 @item @emph{See also}:
5395 @ref{GET_COMMAND}, @ref{COMMAND_ARGUMENT_COUNT}
5401 @section @code{GETCWD} --- Get current working directory
5403 @cindex system, working directory
5406 @item @emph{Description}:
5407 Get current working directory.
5409 This intrinsic is provided in both subroutine and function forms; however,
5410 only one form can be used in any given program unit.
5412 @item @emph{Standard}:
5416 Subroutine, function
5418 @item @emph{Syntax}:
5419 @multitable @columnfractions .80
5420 @item @code{CALL GETCWD(C [, STATUS])}
5421 @item @code{STATUS = GETCWD(C)}
5424 @item @emph{Arguments}:
5425 @multitable @columnfractions .15 .70
5426 @item @var{C} @tab The type shall be @code{CHARACTER} and of default kind.
5427 @item @var{STATUS} @tab (Optional) status flag. Returns 0 on success,
5428 a system specific and nonzero error code otherwise.
5431 @item @emph{Example}:
5434 CHARACTER(len=255) :: cwd
5436 WRITE(*,*) TRIM(cwd)
5440 @item @emph{See also}:
5447 @section @code{GETENV} --- Get an environmental variable
5449 @cindex environment variable
5452 @item @emph{Description}:
5453 Get the @var{VALUE} of the environmental variable @var{NAME}.
5455 This intrinsic routine is provided for backwards compatibility with
5456 GNU Fortran 77. In new code, programmers should consider the use of
5457 the @ref{GET_ENVIRONMENT_VARIABLE} intrinsic defined by the Fortran
5460 @item @emph{Standard}:
5466 @item @emph{Syntax}:
5467 @code{CALL GETENV(NAME, VALUE)}
5469 @item @emph{Arguments}:
5470 @multitable @columnfractions .15 .70
5471 @item @var{NAME} @tab Shall be of type @code{CHARACTER} and of default kind.
5472 @item @var{VALUE} @tab Shall be of type @code{CHARACTER} and of default kind.
5475 @item @emph{Return value}:
5476 Stores the value of @var{NAME} in @var{VALUE}. If @var{VALUE} is
5477 not large enough to hold the data, it is truncated. If @var{NAME}
5478 is not set, @var{VALUE} will be filled with blanks.
5480 @item @emph{Example}:
5483 CHARACTER(len=255) :: homedir
5484 CALL getenv("HOME", homedir)
5485 WRITE (*,*) TRIM(homedir)
5489 @item @emph{See also}:
5490 @ref{GET_ENVIRONMENT_VARIABLE}
5495 @node GET_ENVIRONMENT_VARIABLE
5496 @section @code{GET_ENVIRONMENT_VARIABLE} --- Get an environmental variable
5497 @fnindex GET_ENVIRONMENT_VARIABLE
5498 @cindex environment variable
5501 @item @emph{Description}:
5502 Get the @var{VALUE} of the environmental variable @var{NAME}.
5504 @item @emph{Standard}:
5505 Fortran 2003 and later
5510 @item @emph{Syntax}:
5511 @code{CALL GET_ENVIRONMENT_VARIABLE(NAME[, VALUE, LENGTH, STATUS, TRIM_NAME)}
5513 @item @emph{Arguments}:
5514 @multitable @columnfractions .15 .70
5515 @item @var{NAME} @tab Shall be a scalar of type @code{CHARACTER}
5516 and of default kind.
5517 @item @var{VALUE} @tab Shall be a scalar of type @code{CHARACTER}
5518 and of default kind.
5519 @item @var{LENGTH} @tab Shall be a scalar of type @code{INTEGER}
5520 and of default kind.
5521 @item @var{STATUS} @tab Shall be a scalar of type @code{INTEGER}
5522 and of default kind.
5523 @item @var{TRIM_NAME} @tab Shall be a scalar of type @code{LOGICAL}
5524 and of default kind.
5527 @item @emph{Return value}:
5528 Stores the value of @var{NAME} in @var{VALUE}. If @var{VALUE} is
5529 not large enough to hold the data, it is truncated. If @var{NAME}
5530 is not set, @var{VALUE} will be filled with blanks. Argument @var{LENGTH}
5531 contains the length needed for storing the environment variable @var{NAME}
5532 or zero if it is not present. @var{STATUS} is -1 if @var{VALUE} is present
5533 but too short for the environment variable; it is 1 if the environment
5534 variable does not exist and 2 if the processor does not support environment
5535 variables; in all other cases @var{STATUS} is zero. If @var{TRIM_NAME} is
5536 present with the value @code{.FALSE.}, the trailing blanks in @var{NAME}
5537 are significant; otherwise they are not part of the environment variable
5540 @item @emph{Example}:
5543 CHARACTER(len=255) :: homedir
5544 CALL get_environment_variable("HOME", homedir)
5545 WRITE (*,*) TRIM(homedir)
5553 @section @code{GETGID} --- Group ID function
5555 @cindex system, group ID
5558 @item @emph{Description}:
5559 Returns the numerical group ID of the current process.
5561 @item @emph{Standard}:
5567 @item @emph{Syntax}:
5568 @code{RESULT = GETGID()}
5570 @item @emph{Return value}:
5571 The return value of @code{GETGID} is an @code{INTEGER} of the default
5575 @item @emph{Example}:
5576 See @code{GETPID} for an example.
5578 @item @emph{See also}:
5579 @ref{GETPID}, @ref{GETUID}
5585 @section @code{GETLOG} --- Get login name
5587 @cindex system, login name
5591 @item @emph{Description}:
5592 Gets the username under which the program is running.
5594 @item @emph{Standard}:
5600 @item @emph{Syntax}:
5601 @code{CALL GETLOG(C)}
5603 @item @emph{Arguments}:
5604 @multitable @columnfractions .15 .70
5605 @item @var{C} @tab Shall be of type @code{CHARACTER} and of default kind.
5608 @item @emph{Return value}:
5609 Stores the current user name in @var{LOGIN}. (On systems where POSIX
5610 functions @code{geteuid} and @code{getpwuid} are not available, and
5611 the @code{getlogin} function is not implemented either, this will
5612 return a blank string.)
5614 @item @emph{Example}:
5617 CHARACTER(32) :: login
5623 @item @emph{See also}:
5630 @section @code{GETPID} --- Process ID function
5632 @cindex system, process ID
5636 @item @emph{Description}:
5637 Returns the numerical process identifier of the current process.
5639 @item @emph{Standard}:
5645 @item @emph{Syntax}:
5646 @code{RESULT = GETPID()}
5648 @item @emph{Return value}:
5649 The return value of @code{GETPID} is an @code{INTEGER} of the default
5653 @item @emph{Example}:
5656 print *, "The current process ID is ", getpid()
5657 print *, "Your numerical user ID is ", getuid()
5658 print *, "Your numerical group ID is ", getgid()
5662 @item @emph{See also}:
5663 @ref{GETGID}, @ref{GETUID}
5669 @section @code{GETUID} --- User ID function
5671 @cindex system, user ID
5675 @item @emph{Description}:
5676 Returns the numerical user ID of the current process.
5678 @item @emph{Standard}:
5684 @item @emph{Syntax}:
5685 @code{RESULT = GETUID()}
5687 @item @emph{Return value}:
5688 The return value of @code{GETUID} is an @code{INTEGER} of the default
5692 @item @emph{Example}:
5693 See @code{GETPID} for an example.
5695 @item @emph{See also}:
5696 @ref{GETPID}, @ref{GETLOG}
5702 @section @code{GMTIME} --- Convert time to GMT info
5704 @cindex time, conversion to GMT info
5707 @item @emph{Description}:
5708 Given a system time value @var{TIME} (as provided by the @code{TIME8()}
5709 intrinsic), fills @var{VALUES} with values extracted from it appropriate
5710 to the UTC time zone (Universal Coordinated Time, also known in some
5711 countries as GMT, Greenwich Mean Time), using @code{gmtime(3)}.
5713 @item @emph{Standard}:
5719 @item @emph{Syntax}:
5720 @code{CALL GMTIME(TIME, VALUES)}
5722 @item @emph{Arguments}:
5723 @multitable @columnfractions .15 .70
5724 @item @var{TIME} @tab An @code{INTEGER} scalar expression
5725 corresponding to a system time, with @code{INTENT(IN)}.
5726 @item @var{VALUES} @tab A default @code{INTEGER} array with 9 elements,
5727 with @code{INTENT(OUT)}.
5730 @item @emph{Return value}:
5731 The elements of @var{VALUES} are assigned as follows:
5733 @item Seconds after the minute, range 0--59 or 0--61 to allow for leap
5735 @item Minutes after the hour, range 0--59
5736 @item Hours past midnight, range 0--23
5737 @item Day of month, range 0--31
5738 @item Number of months since January, range 0--12
5739 @item Years since 1900
5740 @item Number of days since Sunday, range 0--6
5741 @item Days since January 1
5742 @item Daylight savings indicator: positive if daylight savings is in
5743 effect, zero if not, and negative if the information is not available.
5746 @item @emph{See also}:
5747 @ref{CTIME}, @ref{LTIME}, @ref{TIME}, @ref{TIME8}
5754 @section @code{HOSTNM} --- Get system host name
5756 @cindex system, host name
5759 @item @emph{Description}:
5760 Retrieves the host name of the system on which the program is running.
5762 This intrinsic is provided in both subroutine and function forms; however,
5763 only one form can be used in any given program unit.
5765 @item @emph{Standard}:
5769 Subroutine, function
5771 @item @emph{Syntax}:
5772 @multitable @columnfractions .80
5773 @item @code{CALL HOSTNM(C [, STATUS])}
5774 @item @code{STATUS = HOSTNM(NAME)}
5777 @item @emph{Arguments}:
5778 @multitable @columnfractions .15 .70
5779 @item @var{C} @tab Shall of type @code{CHARACTER} and of default kind.
5780 @item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER}.
5781 Returns 0 on success, or a system specific error code otherwise.
5784 @item @emph{Return value}:
5785 In either syntax, @var{NAME} is set to the current hostname if it can
5786 be obtained, or to a blank string otherwise.
5793 @section @code{HUGE} --- Largest number of a kind
5795 @cindex limits, largest number
5796 @cindex model representation, largest number
5799 @item @emph{Description}:
5800 @code{HUGE(X)} returns the largest number that is not an infinity in
5801 the model of the type of @code{X}.
5803 @item @emph{Standard}:
5804 Fortran 95 and later
5809 @item @emph{Syntax}:
5810 @code{RESULT = HUGE(X)}
5812 @item @emph{Arguments}:
5813 @multitable @columnfractions .15 .70
5814 @item @var{X} @tab Shall be of type @code{REAL} or @code{INTEGER}.
5817 @item @emph{Return value}:
5818 The return value is of the same type and kind as @var{X}
5820 @item @emph{Example}:
5822 program test_huge_tiny
5823 print *, huge(0), huge(0.0), huge(0.0d0)
5824 print *, tiny(0.0), tiny(0.0d0)
5825 end program test_huge_tiny
5832 @section @code{HYPOT} --- Euclidean distance function
5834 @cindex Euclidean distance
5837 @item @emph{Description}:
5838 @code{HYPOT(X,Y)} is the Euclidean distance function. It is equal to
5839 @math{\sqrt{X^2 + Y^2}}, without undue underflow or overflow.
5841 @item @emph{Standard}:
5842 Fortran 2008 and later
5847 @item @emph{Syntax}:
5848 @code{RESULT = HYPOT(X, Y)}
5850 @item @emph{Arguments}:
5851 @multitable @columnfractions .15 .70
5852 @item @var{X} @tab The type shall be @code{REAL}.
5853 @item @var{Y} @tab The type and kind type parameter shall be the same as
5857 @item @emph{Return value}:
5858 The return value has the same type and kind type parameter as @var{X}.
5860 @item @emph{Example}:
5863 real(4) :: x = 1.e0_4, y = 0.5e0_4
5865 end program test_hypot
5872 @section @code{IACHAR} --- Code in @acronym{ASCII} collating sequence
5874 @cindex @acronym{ASCII} collating sequence
5875 @cindex collating sequence, @acronym{ASCII}
5876 @cindex conversion, to integer
5879 @item @emph{Description}:
5880 @code{IACHAR(C)} returns the code for the @acronym{ASCII} character
5881 in the first character position of @code{C}.
5883 @item @emph{Standard}:
5884 Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
5889 @item @emph{Syntax}:
5890 @code{RESULT = IACHAR(C [, KIND])}
5892 @item @emph{Arguments}:
5893 @multitable @columnfractions .15 .70
5894 @item @var{C} @tab Shall be a scalar @code{CHARACTER}, with @code{INTENT(IN)}
5895 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
5896 expression indicating the kind parameter of the result.
5899 @item @emph{Return value}:
5900 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
5901 @var{KIND} is absent, the return value is of default integer kind.
5903 @item @emph{Example}:
5908 end program test_iachar
5912 See @ref{ICHAR} for a discussion of converting between numerical values
5913 and formatted string representations.
5915 @item @emph{See also}:
5916 @ref{ACHAR}, @ref{CHAR}, @ref{ICHAR}
5923 @section @code{IALL} --- Bitwise AND of array elements
5926 @cindex bits, AND of array elements
5929 @item @emph{Description}:
5930 Reduces with bitwise AND the elements of @var{ARRAY} along dimension @var{DIM}
5931 if the corresponding element in @var{MASK} is @code{TRUE}.
5933 @item @emph{Standard}:
5934 Fortran 2008 and later
5937 Transformational function
5939 @item @emph{Syntax}:
5940 @multitable @columnfractions .80
5941 @item @code{RESULT = IALL(ARRAY[, MASK])}
5942 @item @code{RESULT = IALL(ARRAY, DIM[, MASK])}
5945 @item @emph{Arguments}:
5946 @multitable @columnfractions .15 .70
5947 @item @var{ARRAY} @tab Shall be an array of type @code{INTEGER}
5948 @item @var{DIM} @tab (Optional) shall be a scalar of type
5949 @code{INTEGER} with a value in the range from 1 to n, where n
5950 equals the rank of @var{ARRAY}.
5951 @item @var{MASK} @tab (Optional) shall be of type @code{LOGICAL}
5952 and either be a scalar or an array of the same shape as @var{ARRAY}.
5955 @item @emph{Return value}:
5956 The result is of the same type as @var{ARRAY}.
5958 If @var{DIM} is absent, a scalar with the bitwise ALL of all elements in
5959 @var{ARRAY} is returned. Otherwise, an array of rank n-1, where n equals
5960 the rank of @var{ARRAY}, and a shape similar to that of @var{ARRAY} with
5961 dimension @var{DIM} dropped is returned.
5963 @item @emph{Example}:
5972 PRINT '(b8.8)', IALL(a)
5976 @item @emph{See also}:
5977 @ref{IANY}, @ref{IPARITY}, @ref{IAND}
5983 @section @code{IAND} --- Bitwise logical and
5985 @cindex bitwise logical and
5986 @cindex logical and, bitwise
5989 @item @emph{Description}:
5990 Bitwise logical @code{AND}.
5992 @item @emph{Standard}:
5993 Fortran 95 and later
5998 @item @emph{Syntax}:
5999 @code{RESULT = IAND(I, J)}
6001 @item @emph{Arguments}:
6002 @multitable @columnfractions .15 .70
6003 @item @var{I} @tab The type shall be @code{INTEGER}.
6004 @item @var{J} @tab The type shall be @code{INTEGER}, of the same
6005 kind as @var{I}. (As a GNU extension, different kinds are also
6009 @item @emph{Return value}:
6010 The return type is @code{INTEGER}, of the same kind as the
6011 arguments. (If the argument kinds differ, it is of the same kind as
6012 the larger argument.)
6014 @item @emph{Example}:
6018 DATA a / Z'F' /, b / Z'3' /
6019 WRITE (*,*) IAND(a, b)
6023 @item @emph{See also}:
6024 @ref{IOR}, @ref{IEOR}, @ref{IBITS}, @ref{IBSET}, @ref{IBCLR}, @ref{NOT}
6031 @section @code{IANY} --- Bitwise XOR of array elements
6034 @cindex bits, OR of array elements
6037 @item @emph{Description}:
6038 Reduces with bitwise OR (inclusive or) the elements of @var{ARRAY} along
6039 dimension @var{DIM} if the corresponding element in @var{MASK} is @code{TRUE}.
6041 @item @emph{Standard}:
6042 Fortran 2008 and later
6045 Transformational function
6047 @item @emph{Syntax}:
6048 @multitable @columnfractions .80
6049 @item @code{RESULT = IANY(ARRAY[, MASK])}
6050 @item @code{RESULT = IANY(ARRAY, DIM[, MASK])}
6053 @item @emph{Arguments}:
6054 @multitable @columnfractions .15 .70
6055 @item @var{ARRAY} @tab Shall be an array of type @code{INTEGER}
6056 @item @var{DIM} @tab (Optional) shall be a scalar of type
6057 @code{INTEGER} with a value in the range from 1 to n, where n
6058 equals the rank of @var{ARRAY}.
6059 @item @var{MASK} @tab (Optional) shall be of type @code{LOGICAL}
6060 and either be a scalar or an array of the same shape as @var{ARRAY}.
6063 @item @emph{Return value}:
6064 The result is of the same type as @var{ARRAY}.
6066 If @var{DIM} is absent, a scalar with the bitwise OR of all elements in
6067 @var{ARRAY} is returned. Otherwise, an array of rank n-1, where n equals
6068 the rank of @var{ARRAY}, and a shape similar to that of @var{ARRAY} with
6069 dimension @var{DIM} dropped is returned.
6071 @item @emph{Example}:
6080 PRINT '(b8.8)', IANY(a)
6084 @item @emph{See also}:
6085 @ref{IPARITY}, @ref{IALL}, @ref{IOR}
6091 @section @code{IARGC} --- Get the number of command line arguments
6093 @cindex command-line arguments
6094 @cindex command-line arguments, number of
6095 @cindex arguments, to program
6098 @item @emph{Description}:
6099 @code{IARGC()} returns the number of arguments passed on the
6100 command line when the containing program was invoked.
6102 This intrinsic routine is provided for backwards compatibility with
6103 GNU Fortran 77. In new code, programmers should consider the use of
6104 the @ref{COMMAND_ARGUMENT_COUNT} intrinsic defined by the Fortran 2003
6107 @item @emph{Standard}:
6113 @item @emph{Syntax}:
6114 @code{RESULT = IARGC()}
6116 @item @emph{Arguments}:
6119 @item @emph{Return value}:
6120 The number of command line arguments, type @code{INTEGER(4)}.
6122 @item @emph{Example}:
6125 @item @emph{See also}:
6126 GNU Fortran 77 compatibility subroutine: @ref{GETARG}
6128 Fortran 2003 functions and subroutines: @ref{GET_COMMAND},
6129 @ref{GET_COMMAND_ARGUMENT}, @ref{COMMAND_ARGUMENT_COUNT}
6135 @section @code{IBCLR} --- Clear bit
6141 @item @emph{Description}:
6142 @code{IBCLR} returns the value of @var{I} with the bit at position
6143 @var{POS} set to zero.
6145 @item @emph{Standard}:
6146 Fortran 95 and later
6151 @item @emph{Syntax}:
6152 @code{RESULT = IBCLR(I, POS)}
6154 @item @emph{Arguments}:
6155 @multitable @columnfractions .15 .70
6156 @item @var{I} @tab The type shall be @code{INTEGER}.
6157 @item @var{POS} @tab The type shall be @code{INTEGER}.
6160 @item @emph{Return value}:
6161 The return value is of type @code{INTEGER} and of the same kind as
6164 @item @emph{See also}:
6165 @ref{IBITS}, @ref{IBSET}, @ref{IAND}, @ref{IOR}, @ref{IEOR}, @ref{MVBITS}
6172 @section @code{IBITS} --- Bit extraction
6175 @cindex bits, extract
6178 @item @emph{Description}:
6179 @code{IBITS} extracts a field of length @var{LEN} from @var{I},
6180 starting from bit position @var{POS} and extending left for @var{LEN}
6181 bits. The result is right-justified and the remaining bits are
6182 zeroed. The value of @code{POS+LEN} must be less than or equal to the
6183 value @code{BIT_SIZE(I)}.
6185 @item @emph{Standard}:
6186 Fortran 95 and later
6191 @item @emph{Syntax}:
6192 @code{RESULT = IBITS(I, POS, LEN)}
6194 @item @emph{Arguments}:
6195 @multitable @columnfractions .15 .70
6196 @item @var{I} @tab The type shall be @code{INTEGER}.
6197 @item @var{POS} @tab The type shall be @code{INTEGER}.
6198 @item @var{LEN} @tab The type shall be @code{INTEGER}.
6201 @item @emph{Return value}:
6202 The return value is of type @code{INTEGER} and of the same kind as
6205 @item @emph{See also}:
6206 @ref{BIT_SIZE}, @ref{IBCLR}, @ref{IBSET}, @ref{IAND}, @ref{IOR}, @ref{IEOR}
6212 @section @code{IBSET} --- Set bit
6217 @item @emph{Description}:
6218 @code{IBSET} returns the value of @var{I} with the bit at position
6219 @var{POS} set to one.
6221 @item @emph{Standard}:
6222 Fortran 95 and later
6227 @item @emph{Syntax}:
6228 @code{RESULT = IBSET(I, POS)}
6230 @item @emph{Arguments}:
6231 @multitable @columnfractions .15 .70
6232 @item @var{I} @tab The type shall be @code{INTEGER}.
6233 @item @var{POS} @tab The type shall be @code{INTEGER}.
6236 @item @emph{Return value}:
6237 The return value is of type @code{INTEGER} and of the same kind as
6240 @item @emph{See also}:
6241 @ref{IBCLR}, @ref{IBITS}, @ref{IAND}, @ref{IOR}, @ref{IEOR}, @ref{MVBITS}
6248 @section @code{ICHAR} --- Character-to-integer conversion function
6250 @cindex conversion, to integer
6253 @item @emph{Description}:
6254 @code{ICHAR(C)} returns the code for the character in the first character
6255 position of @code{C} in the system's native character set.
6256 The correspondence between characters and their codes is not necessarily
6257 the same across different GNU Fortran implementations.
6259 @item @emph{Standard}:
6260 Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
6265 @item @emph{Syntax}:
6266 @code{RESULT = ICHAR(C [, KIND])}
6268 @item @emph{Arguments}:
6269 @multitable @columnfractions .15 .70
6270 @item @var{C} @tab Shall be a scalar @code{CHARACTER}, with @code{INTENT(IN)}
6271 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
6272 expression indicating the kind parameter of the result.
6275 @item @emph{Return value}:
6276 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
6277 @var{KIND} is absent, the return value is of default integer kind.
6279 @item @emph{Example}:
6284 end program test_ichar
6287 @item @emph{Specific names}:
6288 @multitable @columnfractions .20 .20 .20 .25
6289 @item Name @tab Argument @tab Return type @tab Standard
6290 @item @code{ICHAR(C)} @tab @code{CHARACTER C} @tab @code{INTEGER(4)} @tab Fortran 77 and later
6294 No intrinsic exists to convert between a numeric value and a formatted
6295 character string representation -- for instance, given the
6296 @code{CHARACTER} value @code{'154'}, obtaining an @code{INTEGER} or
6297 @code{REAL} value with the value 154, or vice versa. Instead, this
6298 functionality is provided by internal-file I/O, as in the following
6303 character(len=10) string, string2
6306 ! Convert a string to a numeric value
6307 read (string,'(I10)') value
6310 ! Convert a value to a formatted string
6311 write (string2,'(I10)') value
6313 end program read_val
6316 @item @emph{See also}:
6317 @ref{ACHAR}, @ref{CHAR}, @ref{IACHAR}
6324 @section @code{IDATE} --- Get current local time subroutine (day/month/year)
6326 @cindex date, current
6327 @cindex current date
6330 @item @emph{Description}:
6331 @code{IDATE(VALUES)} Fills @var{VALUES} with the numerical values at the
6332 current local time. The day (in the range 1-31), month (in the range 1-12),
6333 and year appear in elements 1, 2, and 3 of @var{VALUES}, respectively.
6334 The year has four significant digits.
6336 @item @emph{Standard}:
6342 @item @emph{Syntax}:
6343 @code{CALL IDATE(VALUES)}
6345 @item @emph{Arguments}:
6346 @multitable @columnfractions .15 .70
6347 @item @var{VALUES} @tab The type shall be @code{INTEGER, DIMENSION(3)} and
6348 the kind shall be the default integer kind.
6351 @item @emph{Return value}:
6352 Does not return anything.
6354 @item @emph{Example}:
6357 integer, dimension(3) :: tarray
6362 end program test_idate
6369 @section @code{IEOR} --- Bitwise logical exclusive or
6371 @cindex bitwise logical exclusive or
6372 @cindex logical exclusive or, bitwise
6375 @item @emph{Description}:
6376 @code{IEOR} returns the bitwise Boolean exclusive-OR of @var{I} and
6379 @item @emph{Standard}:
6380 Fortran 95 and later
6385 @item @emph{Syntax}:
6386 @code{RESULT = IEOR(I, J)}
6388 @item @emph{Arguments}:
6389 @multitable @columnfractions .15 .70
6390 @item @var{I} @tab The type shall be @code{INTEGER}.
6391 @item @var{J} @tab The type shall be @code{INTEGER}, of the same
6392 kind as @var{I}. (As a GNU extension, different kinds are also
6396 @item @emph{Return value}:
6397 The return type is @code{INTEGER}, of the same kind as the
6398 arguments. (If the argument kinds differ, it is of the same kind as
6399 the larger argument.)
6401 @item @emph{See also}:
6402 @ref{IOR}, @ref{IAND}, @ref{IBITS}, @ref{IBSET}, @ref{IBCLR}, @ref{NOT}
6408 @section @code{IERRNO} --- Get the last system error number
6410 @cindex system, error handling
6413 @item @emph{Description}:
6414 Returns the last system error number, as given by the C @code{errno()}
6417 @item @emph{Standard}:
6423 @item @emph{Syntax}:
6424 @code{RESULT = IERRNO()}
6426 @item @emph{Arguments}:
6429 @item @emph{Return value}:
6430 The return value is of type @code{INTEGER} and of the default integer
6433 @item @emph{See also}:
6440 @section @code{IMAGE_INDEX} --- Function that converts a cosubscript to an image index
6441 @fnindex IMAGE_INDEX
6442 @cindex coarray, @code{IMAGE_INDEX}
6443 @cindex images, cosubscript to image index conversion
6446 @item @emph{Description}:
6447 Returns the image index belonging to a cosubscript.
6449 @item @emph{Standard}:
6450 Fortran 2008 and later
6455 @item @emph{Syntax}:
6456 @code{RESULT = IMAGE_INDEX(COARRAY, SUB)}
6458 @item @emph{Arguments}: None.
6459 @multitable @columnfractions .15 .70
6460 @item @var{COARRAY} @tab Coarray of any type.
6461 @item @var{SUB} @tab default integer rank-1 array of a size equal to
6462 the corank of @var{COARRAY}.
6466 @item @emph{Return value}:
6467 Scalar default integer with the value of the image index which corresponds
6468 to the cosubscripts. For invalid cosubscripts the result is zero.
6470 @item @emph{Example}:
6472 INTEGER :: array[2,-1:4,8,*]
6473 ! Writes 28 (or 0 if there are fewer than 28 images)
6474 WRITE (*,*) IMAGE_INDEX (array, [2,0,3,1])
6477 @item @emph{See also}:
6478 @ref{THIS_IMAGE}, @ref{NUM_IMAGES}
6483 @node INDEX intrinsic
6484 @section @code{INDEX} --- Position of a substring within a string
6486 @cindex substring position
6487 @cindex string, find substring
6490 @item @emph{Description}:
6491 Returns the position of the start of the first occurrence of string
6492 @var{SUBSTRING} as a substring in @var{STRING}, counting from one. If
6493 @var{SUBSTRING} is not present in @var{STRING}, zero is returned. If
6494 the @var{BACK} argument is present and true, the return value is the
6495 start of the last occurrence rather than the first.
6497 @item @emph{Standard}:
6498 Fortran 77 and later, with @var{KIND} argument Fortran 2003 and later
6503 @item @emph{Syntax}:
6504 @code{RESULT = INDEX(STRING, SUBSTRING [, BACK [, KIND]])}
6506 @item @emph{Arguments}:
6507 @multitable @columnfractions .15 .70
6508 @item @var{STRING} @tab Shall be a scalar @code{CHARACTER}, with
6510 @item @var{SUBSTRING} @tab Shall be a scalar @code{CHARACTER}, with
6512 @item @var{BACK} @tab (Optional) Shall be a scalar @code{LOGICAL}, with
6514 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
6515 expression indicating the kind parameter of the result.
6518 @item @emph{Return value}:
6519 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
6520 @var{KIND} is absent, the return value is of default integer kind.
6522 @item @emph{Specific names}:
6523 @multitable @columnfractions .20 .20 .20 .25
6524 @item Name @tab Argument @tab Return type @tab Standard
6525 @item @code{INDEX(STRING, SUBSTRING)} @tab @code{CHARACTER} @tab @code{INTEGER(4)} @tab Fortran 77 and later
6528 @item @emph{See also}:
6529 @ref{SCAN}, @ref{VERIFY}
6535 @section @code{INT} --- Convert to integer type
6539 @cindex conversion, to integer
6542 @item @emph{Description}:
6543 Convert to integer type
6545 @item @emph{Standard}:
6546 Fortran 77 and later
6551 @item @emph{Syntax}:
6552 @code{RESULT = INT(A [, KIND))}
6554 @item @emph{Arguments}:
6555 @multitable @columnfractions .15 .70
6556 @item @var{A} @tab Shall be of type @code{INTEGER},
6557 @code{REAL}, or @code{COMPLEX}.
6558 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
6559 expression indicating the kind parameter of the result.
6562 @item @emph{Return value}:
6563 These functions return a @code{INTEGER} variable or array under
6564 the following rules:
6568 If @var{A} is of type @code{INTEGER}, @code{INT(A) = A}
6570 If @var{A} is of type @code{REAL} and @math{|A| < 1}, @code{INT(A)} equals @code{0}.
6571 If @math{|A| \geq 1}, then @code{INT(A)} equals the largest integer that does not exceed
6572 the range of @var{A} and whose sign is the same as the sign of @var{A}.
6574 If @var{A} is of type @code{COMPLEX}, rule B is applied to the real part of @var{A}.
6577 @item @emph{Example}:
6581 complex :: z = (-3.7, 1.0)
6583 print *, int(z), int(z,8)
6587 @item @emph{Specific names}:
6588 @multitable @columnfractions .20 .20 .20 .25
6589 @item Name @tab Argument @tab Return type @tab Standard
6590 @item @code{INT(A)} @tab @code{REAL(4) A} @tab @code{INTEGER} @tab Fortran 77 and later
6591 @item @code{IFIX(A)} @tab @code{REAL(4) A} @tab @code{INTEGER} @tab Fortran 77 and later
6592 @item @code{IDINT(A)} @tab @code{REAL(8) A} @tab @code{INTEGER} @tab Fortran 77 and later
6599 @section @code{INT2} --- Convert to 16-bit integer type
6602 @cindex conversion, to integer
6605 @item @emph{Description}:
6606 Convert to a @code{KIND=2} integer type. This is equivalent to the
6607 standard @code{INT} intrinsic with an optional argument of
6608 @code{KIND=2}, and is only included for backwards compatibility.
6610 The @code{SHORT} intrinsic is equivalent to @code{INT2}.
6612 @item @emph{Standard}:
6618 @item @emph{Syntax}:
6619 @code{RESULT = INT2(A)}
6621 @item @emph{Arguments}:
6622 @multitable @columnfractions .15 .70
6623 @item @var{A} @tab Shall be of type @code{INTEGER},
6624 @code{REAL}, or @code{COMPLEX}.
6627 @item @emph{Return value}:
6628 The return value is a @code{INTEGER(2)} variable.
6630 @item @emph{See also}:
6631 @ref{INT}, @ref{INT8}, @ref{LONG}
6637 @section @code{INT8} --- Convert to 64-bit integer type
6639 @cindex conversion, to integer
6642 @item @emph{Description}:
6643 Convert to a @code{KIND=8} integer type. This is equivalent to the
6644 standard @code{INT} intrinsic with an optional argument of
6645 @code{KIND=8}, and is only included for backwards compatibility.
6647 @item @emph{Standard}:
6653 @item @emph{Syntax}:
6654 @code{RESULT = INT8(A)}
6656 @item @emph{Arguments}:
6657 @multitable @columnfractions .15 .70
6658 @item @var{A} @tab Shall be of type @code{INTEGER},
6659 @code{REAL}, or @code{COMPLEX}.
6662 @item @emph{Return value}:
6663 The return value is a @code{INTEGER(8)} variable.
6665 @item @emph{See also}:
6666 @ref{INT}, @ref{INT2}, @ref{LONG}
6672 @section @code{IOR} --- Bitwise logical or
6674 @cindex bitwise logical or
6675 @cindex logical or, bitwise
6678 @item @emph{Description}:
6679 @code{IOR} returns the bitwise Boolean inclusive-OR of @var{I} and
6682 @item @emph{Standard}:
6683 Fortran 95 and later
6688 @item @emph{Syntax}:
6689 @code{RESULT = IOR(I, J)}
6691 @item @emph{Arguments}:
6692 @multitable @columnfractions .15 .70
6693 @item @var{I} @tab The type shall be @code{INTEGER}.
6694 @item @var{J} @tab The type shall be @code{INTEGER}, of the same
6695 kind as @var{I}. (As a GNU extension, different kinds are also
6699 @item @emph{Return value}:
6700 The return type is @code{INTEGER}, of the same kind as the
6701 arguments. (If the argument kinds differ, it is of the same kind as
6702 the larger argument.)
6704 @item @emph{See also}:
6705 @ref{IEOR}, @ref{IAND}, @ref{IBITS}, @ref{IBSET}, @ref{IBCLR}, @ref{NOT}
6711 @section @code{IPARITY} --- Bitwise XOR of array elements
6713 @cindex array, parity
6715 @cindex bits, XOR of array elements
6718 @item @emph{Description}:
6719 Reduces with bitwise XOR (exclusive or) the elements of @var{ARRAY} along
6720 dimension @var{DIM} if the corresponding element in @var{MASK} is @code{TRUE}.
6722 @item @emph{Standard}:
6723 Fortran 2008 and later
6726 Transformational function
6728 @item @emph{Syntax}:
6729 @multitable @columnfractions .80
6730 @item @code{RESULT = IPARITY(ARRAY[, MASK])}
6731 @item @code{RESULT = IPARITY(ARRAY, DIM[, MASK])}
6734 @item @emph{Arguments}:
6735 @multitable @columnfractions .15 .70
6736 @item @var{ARRAY} @tab Shall be an array of type @code{INTEGER}
6737 @item @var{DIM} @tab (Optional) shall be a scalar of type
6738 @code{INTEGER} with a value in the range from 1 to n, where n
6739 equals the rank of @var{ARRAY}.
6740 @item @var{MASK} @tab (Optional) shall be of type @code{LOGICAL}
6741 and either be a scalar or an array of the same shape as @var{ARRAY}.
6744 @item @emph{Return value}:
6745 The result is of the same type as @var{ARRAY}.
6747 If @var{DIM} is absent, a scalar with the bitwise XOR of all elements in
6748 @var{ARRAY} is returned. Otherwise, an array of rank n-1, where n equals
6749 the rank of @var{ARRAY}, and a shape similar to that of @var{ARRAY} with
6750 dimension @var{DIM} dropped is returned.
6752 @item @emph{Example}:
6754 PROGRAM test_iparity
6761 PRINT '(b8.8)', IPARITY(a)
6765 @item @emph{See also}:
6766 @ref{IANY}, @ref{IALL}, @ref{IEOR}, @ref{PARITY}
6772 @section @code{IRAND} --- Integer pseudo-random number
6774 @cindex random number generation
6777 @item @emph{Description}:
6778 @code{IRAND(FLAG)} returns a pseudo-random number from a uniform
6779 distribution between 0 and a system-dependent limit (which is in most
6780 cases 2147483647). If @var{FLAG} is 0, the next number
6781 in the current sequence is returned; if @var{FLAG} is 1, the generator
6782 is restarted by @code{CALL SRAND(0)}; if @var{FLAG} has any other value,
6783 it is used as a new seed with @code{SRAND}.
6785 This intrinsic routine is provided for backwards compatibility with
6786 GNU Fortran 77. It implements a simple modulo generator as provided
6787 by @command{g77}. For new code, one should consider the use of
6788 @ref{RANDOM_NUMBER} as it implements a superior algorithm.
6790 @item @emph{Standard}:
6796 @item @emph{Syntax}:
6797 @code{RESULT = IRAND(I)}
6799 @item @emph{Arguments}:
6800 @multitable @columnfractions .15 .70
6801 @item @var{I} @tab Shall be a scalar @code{INTEGER} of kind 4.
6804 @item @emph{Return value}:
6805 The return value is of @code{INTEGER(kind=4)} type.
6807 @item @emph{Example}:
6810 integer,parameter :: seed = 86456
6813 print *, irand(), irand(), irand(), irand()
6814 print *, irand(seed), irand(), irand(), irand()
6815 end program test_irand
6823 @section @code{IS_IOSTAT_END} --- Test for end-of-file value
6824 @fnindex IS_IOSTAT_END
6825 @cindex @code{IOSTAT}, end of file
6828 @item @emph{Description}:
6829 @code{IS_IOSTAT_END} tests whether an variable has the value of the I/O
6830 status ``end of file''. The function is equivalent to comparing the variable
6831 with the @code{IOSTAT_END} parameter of the intrinsic module
6832 @code{ISO_FORTRAN_ENV}.
6834 @item @emph{Standard}:
6835 Fortran 2003 and later
6840 @item @emph{Syntax}:
6841 @code{RESULT = IS_IOSTAT_END(I)}
6843 @item @emph{Arguments}:
6844 @multitable @columnfractions .15 .70
6845 @item @var{I} @tab Shall be of the type @code{INTEGER}.
6848 @item @emph{Return value}:
6849 Returns a @code{LOGICAL} of the default kind, which @code{.TRUE.} if
6850 @var{I} has the value which indicates an end of file condition for
6851 @code{IOSTAT=} specifiers, and is @code{.FALSE.} otherwise.
6853 @item @emph{Example}:
6858 OPEN(88, FILE='test.dat')
6859 READ(88, *, IOSTAT=stat) i
6860 IF(IS_IOSTAT_END(stat)) STOP 'END OF FILE'
6868 @section @code{IS_IOSTAT_EOR} --- Test for end-of-record value
6869 @fnindex IS_IOSTAT_EOR
6870 @cindex @code{IOSTAT}, end of record
6873 @item @emph{Description}:
6874 @code{IS_IOSTAT_EOR} tests whether an variable has the value of the I/O
6875 status ``end of record''. The function is equivalent to comparing the
6876 variable with the @code{IOSTAT_EOR} parameter of the intrinsic module
6877 @code{ISO_FORTRAN_ENV}.
6879 @item @emph{Standard}:
6880 Fortran 2003 and later
6885 @item @emph{Syntax}:
6886 @code{RESULT = IS_IOSTAT_EOR(I)}
6888 @item @emph{Arguments}:
6889 @multitable @columnfractions .15 .70
6890 @item @var{I} @tab Shall be of the type @code{INTEGER}.
6893 @item @emph{Return value}:
6894 Returns a @code{LOGICAL} of the default kind, which @code{.TRUE.} if
6895 @var{I} has the value which indicates an end of file condition for
6896 @code{IOSTAT=} specifiers, and is @code{.FALSE.} otherwise.
6898 @item @emph{Example}:
6902 INTEGER :: stat, i(50)
6903 OPEN(88, FILE='test.dat', FORM='UNFORMATTED')
6904 READ(88, IOSTAT=stat) i
6905 IF(IS_IOSTAT_EOR(stat)) STOP 'END OF RECORD'
6913 @section @code{ISATTY} --- Whether a unit is a terminal device.
6915 @cindex system, terminal
6918 @item @emph{Description}:
6919 Determine whether a unit is connected to a terminal device.
6921 @item @emph{Standard}:
6927 @item @emph{Syntax}:
6928 @code{RESULT = ISATTY(UNIT)}
6930 @item @emph{Arguments}:
6931 @multitable @columnfractions .15 .70
6932 @item @var{UNIT} @tab Shall be a scalar @code{INTEGER}.
6935 @item @emph{Return value}:
6936 Returns @code{.TRUE.} if the @var{UNIT} is connected to a terminal
6937 device, @code{.FALSE.} otherwise.
6939 @item @emph{Example}:
6942 INTEGER(kind=1) :: unit
6944 write(*,*) isatty(unit=unit)
6948 @item @emph{See also}:
6955 @section @code{ISHFT} --- Shift bits
6960 @item @emph{Description}:
6961 @code{ISHFT} returns a value corresponding to @var{I} with all of the
6962 bits shifted @var{SHIFT} places. A value of @var{SHIFT} greater than
6963 zero corresponds to a left shift, a value of zero corresponds to no
6964 shift, and a value less than zero corresponds to a right shift. If the
6965 absolute value of @var{SHIFT} is greater than @code{BIT_SIZE(I)}, the
6966 value is undefined. Bits shifted out from the left end or right end are
6967 lost; zeros are shifted in from the opposite end.
6969 @item @emph{Standard}:
6970 Fortran 95 and later
6975 @item @emph{Syntax}:
6976 @code{RESULT = ISHFT(I, SHIFT)}
6978 @item @emph{Arguments}:
6979 @multitable @columnfractions .15 .70
6980 @item @var{I} @tab The type shall be @code{INTEGER}.
6981 @item @var{SHIFT} @tab The type shall be @code{INTEGER}.
6984 @item @emph{Return value}:
6985 The return value is of type @code{INTEGER} and of the same kind as
6988 @item @emph{See also}:
6995 @section @code{ISHFTC} --- Shift bits circularly
6997 @cindex bits, shift circular
7000 @item @emph{Description}:
7001 @code{ISHFTC} returns a value corresponding to @var{I} with the
7002 rightmost @var{SIZE} bits shifted circularly @var{SHIFT} places; that
7003 is, bits shifted out one end are shifted into the opposite end. A value
7004 of @var{SHIFT} greater than zero corresponds to a left shift, a value of
7005 zero corresponds to no shift, and a value less than zero corresponds to
7006 a right shift. The absolute value of @var{SHIFT} must be less than
7007 @var{SIZE}. If the @var{SIZE} argument is omitted, it is taken to be
7008 equivalent to @code{BIT_SIZE(I)}.
7010 @item @emph{Standard}:
7011 Fortran 95 and later
7016 @item @emph{Syntax}:
7017 @code{RESULT = ISHFTC(I, SHIFT [, SIZE])}
7019 @item @emph{Arguments}:
7020 @multitable @columnfractions .15 .70
7021 @item @var{I} @tab The type shall be @code{INTEGER}.
7022 @item @var{SHIFT} @tab The type shall be @code{INTEGER}.
7023 @item @var{SIZE} @tab (Optional) The type shall be @code{INTEGER};
7024 the value must be greater than zero and less than or equal to
7028 @item @emph{Return value}:
7029 The return value is of type @code{INTEGER} and of the same kind as
7032 @item @emph{See also}:
7039 @section @code{ISNAN} --- Test for a NaN
7044 @item @emph{Description}:
7045 @code{ISNAN} tests whether a floating-point value is an IEEE
7047 @item @emph{Standard}:
7053 @item @emph{Syntax}:
7056 @item @emph{Arguments}:
7057 @multitable @columnfractions .15 .70
7058 @item @var{X} @tab Variable of the type @code{REAL}.
7062 @item @emph{Return value}:
7063 Returns a default-kind @code{LOGICAL}. The returned value is @code{TRUE}
7064 if @var{X} is a NaN and @code{FALSE} otherwise.
7066 @item @emph{Example}:
7073 if (isnan(x)) stop '"x" is a NaN'
7074 end program test_nan
7081 @section @code{ITIME} --- Get current local time subroutine (hour/minutes/seconds)
7083 @cindex time, current
7084 @cindex current time
7087 @item @emph{Description}:
7088 @code{IDATE(VALUES)} Fills @var{VALUES} with the numerical values at the
7089 current local time. The hour (in the range 1-24), minute (in the range 1-60),
7090 and seconds (in the range 1-60) appear in elements 1, 2, and 3 of @var{VALUES},
7093 @item @emph{Standard}:
7099 @item @emph{Syntax}:
7100 @code{CALL ITIME(VALUES)}
7102 @item @emph{Arguments}:
7103 @multitable @columnfractions .15 .70
7104 @item @var{VALUES} @tab The type shall be @code{INTEGER, DIMENSION(3)}
7105 and the kind shall be the default integer kind.
7108 @item @emph{Return value}:
7109 Does not return anything.
7112 @item @emph{Example}:
7115 integer, dimension(3) :: tarray
7120 end program test_itime
7127 @section @code{KILL} --- Send a signal to a process
7131 @item @emph{Description}:
7132 @item @emph{Standard}:
7133 Sends the signal specified by @var{SIGNAL} to the process @var{PID}.
7136 This intrinsic is provided in both subroutine and function forms; however,
7137 only one form can be used in any given program unit.
7140 Subroutine, function
7142 @item @emph{Syntax}:
7143 @multitable @columnfractions .80
7144 @item @code{CALL KILL(C, VALUE [, STATUS])}
7145 @item @code{STATUS = KILL(C, VALUE)}
7148 @item @emph{Arguments}:
7149 @multitable @columnfractions .15 .70
7150 @item @var{C} @tab Shall be a scalar @code{INTEGER}, with
7152 @item @var{VALUE} @tab Shall be a scalar @code{INTEGER}, with
7154 @item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER(4)} or
7155 @code{INTEGER(8)}. Returns 0 on success, or a system-specific error code
7159 @item @emph{See also}:
7160 @ref{ABORT}, @ref{EXIT}
7166 @section @code{KIND} --- Kind of an entity
7171 @item @emph{Description}:
7172 @code{KIND(X)} returns the kind value of the entity @var{X}.
7174 @item @emph{Standard}:
7175 Fortran 95 and later
7180 @item @emph{Syntax}:
7183 @item @emph{Arguments}:
7184 @multitable @columnfractions .15 .70
7185 @item @var{X} @tab Shall be of type @code{LOGICAL}, @code{INTEGER},
7186 @code{REAL}, @code{COMPLEX} or @code{CHARACTER}.
7189 @item @emph{Return value}:
7190 The return value is a scalar of type @code{INTEGER} and of the default
7193 @item @emph{Example}:
7196 integer,parameter :: kc = kind(' ')
7197 integer,parameter :: kl = kind(.true.)
7199 print *, "The default character kind is ", kc
7200 print *, "The default logical kind is ", kl
7201 end program test_kind
7209 @section @code{LBOUND} --- Lower dimension bounds of an array
7211 @cindex array, lower bound
7214 @item @emph{Description}:
7215 Returns the lower bounds of an array, or a single lower bound
7216 along the @var{DIM} dimension.
7217 @item @emph{Standard}:
7218 Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
7223 @item @emph{Syntax}:
7224 @code{RESULT = LBOUND(ARRAY [, DIM [, KIND]])}
7226 @item @emph{Arguments}:
7227 @multitable @columnfractions .15 .70
7228 @item @var{ARRAY} @tab Shall be an array, of any type.
7229 @item @var{DIM} @tab (Optional) Shall be a scalar @code{INTEGER}.
7230 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
7231 expression indicating the kind parameter of the result.
7234 @item @emph{Return value}:
7235 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
7236 @var{KIND} is absent, the return value is of default integer kind.
7237 If @var{DIM} is absent, the result is an array of the lower bounds of
7238 @var{ARRAY}. If @var{DIM} is present, the result is a scalar
7239 corresponding to the lower bound of the array along that dimension. If
7240 @var{ARRAY} is an expression rather than a whole array or array
7241 structure component, or if it has a zero extent along the relevant
7242 dimension, the lower bound is taken to be 1.
7244 @item @emph{See also}:
7245 @ref{UBOUND}, @ref{LCOBOUND}
7251 @section @code{LCOBOUND} --- Lower codimension bounds of an array
7253 @cindex coarray, lower bound
7256 @item @emph{Description}:
7257 Returns the lower bounds of a coarray, or a single lower cobound
7258 along the @var{DIM} codimension.
7259 @item @emph{Standard}:
7260 Fortran 2008 and later
7265 @item @emph{Syntax}:
7266 @code{RESULT = LCOBOUND(COARRAY [, DIM [, KIND]])}
7268 @item @emph{Arguments}:
7269 @multitable @columnfractions .15 .70
7270 @item @var{ARRAY} @tab Shall be an coarray, of any type.
7271 @item @var{DIM} @tab (Optional) Shall be a scalar @code{INTEGER}.
7272 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
7273 expression indicating the kind parameter of the result.
7276 @item @emph{Return value}:
7277 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
7278 @var{KIND} is absent, the return value is of default integer kind.
7279 If @var{DIM} is absent, the result is an array of the lower cobounds of
7280 @var{COARRAY}. If @var{DIM} is present, the result is a scalar
7281 corresponding to the lower cobound of the array along that codimension.
7283 @item @emph{See also}:
7284 @ref{UCOBOUND}, @ref{LBOUND}
7290 @section @code{LEADZ} --- Number of leading zero bits of an integer
7295 @item @emph{Description}:
7296 @code{LEADZ} returns the number of leading zero bits of an integer.
7298 @item @emph{Standard}:
7299 Fortran 2008 and later
7304 @item @emph{Syntax}:
7305 @code{RESULT = LEADZ(I)}
7307 @item @emph{Arguments}:
7308 @multitable @columnfractions .15 .70
7309 @item @var{I} @tab Shall be of type @code{INTEGER}.
7312 @item @emph{Return value}:
7313 The type of the return value is the default @code{INTEGER}.
7314 If all the bits of @code{I} are zero, the result value is @code{BIT_SIZE(I)}.
7316 @item @emph{Example}:
7319 WRITE (*,*) LEADZ(1) ! prints 8 if BITSIZE(I) has the value 32
7323 @item @emph{See also}:
7324 @ref{BIT_SIZE}, @ref{TRAILZ}, @ref{POPCNT}, @ref{POPPAR}
7330 @section @code{LEN} --- Length of a character entity
7332 @cindex string, length
7335 @item @emph{Description}:
7336 Returns the length of a character string. If @var{STRING} is an array,
7337 the length of an element of @var{STRING} is returned. Note that
7338 @var{STRING} need not be defined when this intrinsic is invoked, since
7339 only the length, not the content, of @var{STRING} is needed.
7341 @item @emph{Standard}:
7342 Fortran 77 and later, with @var{KIND} argument Fortran 2003 and later
7347 @item @emph{Syntax}:
7348 @code{L = LEN(STRING [, KIND])}
7350 @item @emph{Arguments}:
7351 @multitable @columnfractions .15 .70
7352 @item @var{STRING} @tab Shall be a scalar or array of type
7353 @code{CHARACTER}, with @code{INTENT(IN)}
7354 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
7355 expression indicating the kind parameter of the result.
7358 @item @emph{Return value}:
7359 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
7360 @var{KIND} is absent, the return value is of default integer kind.
7363 @item @emph{Specific names}:
7364 @multitable @columnfractions .20 .20 .20 .25
7365 @item Name @tab Argument @tab Return type @tab Standard
7366 @item @code{LEN(STRING)} @tab @code{CHARACTER} @tab @code{INTEGER} @tab Fortran 77 and later
7370 @item @emph{See also}:
7371 @ref{LEN_TRIM}, @ref{ADJUSTL}, @ref{ADJUSTR}
7377 @section @code{LEN_TRIM} --- Length of a character entity without trailing blank characters
7379 @cindex string, length, without trailing whitespace
7382 @item @emph{Description}:
7383 Returns the length of a character string, ignoring any trailing blanks.
7385 @item @emph{Standard}:
7386 Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
7391 @item @emph{Syntax}:
7392 @code{RESULT = LEN_TRIM(STRING [, KIND])}
7394 @item @emph{Arguments}:
7395 @multitable @columnfractions .15 .70
7396 @item @var{STRING} @tab Shall be a scalar of type @code{CHARACTER},
7397 with @code{INTENT(IN)}
7398 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
7399 expression indicating the kind parameter of the result.
7402 @item @emph{Return value}:
7403 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
7404 @var{KIND} is absent, the return value is of default integer kind.
7406 @item @emph{See also}:
7407 @ref{LEN}, @ref{ADJUSTL}, @ref{ADJUSTR}
7413 @section @code{LGE} --- Lexical greater than or equal
7415 @cindex lexical comparison of strings
7416 @cindex string, comparison
7419 @item @emph{Description}:
7420 Determines whether one string is lexically greater than or equal to
7421 another string, where the two strings are interpreted as containing
7422 ASCII character codes. If the String A and String B are not the same
7423 length, the shorter is compared as if spaces were appended to it to form
7424 a value that has the same length as the longer.
7426 In general, the lexical comparison intrinsics @code{LGE}, @code{LGT},
7427 @code{LLE}, and @code{LLT} differ from the corresponding intrinsic
7428 operators @code{.GE.}, @code{.GT.}, @code{.LE.}, and @code{.LT.}, in
7429 that the latter use the processor's character ordering (which is not
7430 ASCII on some targets), whereas the former always use the ASCII
7433 @item @emph{Standard}:
7434 Fortran 77 and later
7439 @item @emph{Syntax}:
7440 @code{RESULT = LGE(STRING_A, STRING_B)}
7442 @item @emph{Arguments}:
7443 @multitable @columnfractions .15 .70
7444 @item @var{STRING_A} @tab Shall be of default @code{CHARACTER} type.
7445 @item @var{STRING_B} @tab Shall be of default @code{CHARACTER} type.
7448 @item @emph{Return value}:
7449 Returns @code{.TRUE.} if @code{STRING_A >= STRING_B}, and @code{.FALSE.}
7450 otherwise, based on the ASCII ordering.
7452 @item @emph{Specific names}:
7453 @multitable @columnfractions .20 .20 .20 .25
7454 @item Name @tab Argument @tab Return type @tab Standard
7455 @item @code{LGE(STRING_A, STRING_B)} @tab @code{CHARACTER} @tab @code{LOGICAL} @tab Fortran 77 and later
7458 @item @emph{See also}:
7459 @ref{LGT}, @ref{LLE}, @ref{LLT}
7465 @section @code{LGT} --- Lexical greater than
7467 @cindex lexical comparison of strings
7468 @cindex string, comparison
7471 @item @emph{Description}:
7472 Determines whether one string is lexically greater than another string,
7473 where the two strings are interpreted as containing ASCII character
7474 codes. If the String A and String B are not the same length, the
7475 shorter is compared as if spaces were appended to it to form a value
7476 that has the same length as the longer.
7478 In general, the lexical comparison intrinsics @code{LGE}, @code{LGT},
7479 @code{LLE}, and @code{LLT} differ from the corresponding intrinsic
7480 operators @code{.GE.}, @code{.GT.}, @code{.LE.}, and @code{.LT.}, in
7481 that the latter use the processor's character ordering (which is not
7482 ASCII on some targets), whereas the former always use the ASCII
7485 @item @emph{Standard}:
7486 Fortran 77 and later
7491 @item @emph{Syntax}:
7492 @code{RESULT = LGT(STRING_A, STRING_B)}
7494 @item @emph{Arguments}:
7495 @multitable @columnfractions .15 .70
7496 @item @var{STRING_A} @tab Shall be of default @code{CHARACTER} type.
7497 @item @var{STRING_B} @tab Shall be of default @code{CHARACTER} type.
7500 @item @emph{Return value}:
7501 Returns @code{.TRUE.} if @code{STRING_A > STRING_B}, and @code{.FALSE.}
7502 otherwise, based on the ASCII ordering.
7504 @item @emph{Specific names}:
7505 @multitable @columnfractions .20 .20 .20 .25
7506 @item Name @tab Argument @tab Return type @tab Standard
7507 @item @code{LGT(STRING_A, STRING_B)} @tab @code{CHARACTER} @tab @code{LOGICAL} @tab Fortran 77 and later
7510 @item @emph{See also}:
7511 @ref{LGE}, @ref{LLE}, @ref{LLT}
7517 @section @code{LINK} --- Create a hard link
7519 @cindex file system, create link
7520 @cindex file system, hard link
7523 @item @emph{Description}:
7524 Makes a (hard) link from file @var{PATH1} to @var{PATH2}. A null
7525 character (@code{CHAR(0)}) can be used to mark the end of the names in
7526 @var{PATH1} and @var{PATH2}; otherwise, trailing blanks in the file
7527 names are ignored. If the @var{STATUS} argument is supplied, it
7528 contains 0 on success or a nonzero error code upon return; see
7531 This intrinsic is provided in both subroutine and function forms;
7532 however, only one form can be used in any given program unit.
7534 @item @emph{Standard}:
7538 Subroutine, function
7540 @item @emph{Syntax}:
7541 @multitable @columnfractions .80
7542 @item @code{CALL LINK(PATH1, PATH2 [, STATUS])}
7543 @item @code{STATUS = LINK(PATH1, PATH2)}
7546 @item @emph{Arguments}:
7547 @multitable @columnfractions .15 .70
7548 @item @var{PATH1} @tab Shall be of default @code{CHARACTER} type.
7549 @item @var{PATH2} @tab Shall be of default @code{CHARACTER} type.
7550 @item @var{STATUS} @tab (Optional) Shall be of default @code{INTEGER} type.
7553 @item @emph{See also}:
7554 @ref{SYMLNK}, @ref{UNLINK}
7560 @section @code{LLE} --- Lexical less than or equal
7562 @cindex lexical comparison of strings
7563 @cindex string, comparison
7566 @item @emph{Description}:
7567 Determines whether one string is lexically less than or equal to another
7568 string, where the two strings are interpreted as containing ASCII
7569 character codes. If the String A and String B are not the same length,
7570 the shorter is compared as if spaces were appended to it to form a value
7571 that has the same length as the longer.
7573 In general, the lexical comparison intrinsics @code{LGE}, @code{LGT},
7574 @code{LLE}, and @code{LLT} differ from the corresponding intrinsic
7575 operators @code{.GE.}, @code{.GT.}, @code{.LE.}, and @code{.LT.}, in
7576 that the latter use the processor's character ordering (which is not
7577 ASCII on some targets), whereas the former always use the ASCII
7580 @item @emph{Standard}:
7581 Fortran 77 and later
7586 @item @emph{Syntax}:
7587 @code{RESULT = LLE(STRING_A, STRING_B)}
7589 @item @emph{Arguments}:
7590 @multitable @columnfractions .15 .70
7591 @item @var{STRING_A} @tab Shall be of default @code{CHARACTER} type.
7592 @item @var{STRING_B} @tab Shall be of default @code{CHARACTER} type.
7595 @item @emph{Return value}:
7596 Returns @code{.TRUE.} if @code{STRING_A <= STRING_B}, and @code{.FALSE.}
7597 otherwise, based on the ASCII ordering.
7599 @item @emph{Specific names}:
7600 @multitable @columnfractions .20 .20 .20 .25
7601 @item Name @tab Argument @tab Return type @tab Standard
7602 @item @code{LLE(STRING_A, STRING_B)} @tab @code{CHARACTER} @tab @code{LOGICAL} @tab Fortran 77 and later
7605 @item @emph{See also}:
7606 @ref{LGE}, @ref{LGT}, @ref{LLT}
7612 @section @code{LLT} --- Lexical less than
7614 @cindex lexical comparison of strings
7615 @cindex string, comparison
7618 @item @emph{Description}:
7619 Determines whether one string is lexically less than another string,
7620 where the two strings are interpreted as containing ASCII character
7621 codes. If the String A and String B are not the same length, the
7622 shorter is compared as if spaces were appended to it to form a value
7623 that has the same length as the longer.
7625 In general, the lexical comparison intrinsics @code{LGE}, @code{LGT},
7626 @code{LLE}, and @code{LLT} differ from the corresponding intrinsic
7627 operators @code{.GE.}, @code{.GT.}, @code{.LE.}, and @code{.LT.}, in
7628 that the latter use the processor's character ordering (which is not
7629 ASCII on some targets), whereas the former always use the ASCII
7632 @item @emph{Standard}:
7633 Fortran 77 and later
7638 @item @emph{Syntax}:
7639 @code{RESULT = LLT(STRING_A, STRING_B)}
7641 @item @emph{Arguments}:
7642 @multitable @columnfractions .15 .70
7643 @item @var{STRING_A} @tab Shall be of default @code{CHARACTER} type.
7644 @item @var{STRING_B} @tab Shall be of default @code{CHARACTER} type.
7647 @item @emph{Return value}:
7648 Returns @code{.TRUE.} if @code{STRING_A < STRING_B}, and @code{.FALSE.}
7649 otherwise, based on the ASCII ordering.
7651 @item @emph{Specific names}:
7652 @multitable @columnfractions .20 .20 .20 .25
7653 @item Name @tab Argument @tab Return type @tab Standard
7654 @item @code{LLT(STRING_A, STRING_B)} @tab @code{CHARACTER} @tab @code{LOGICAL} @tab Fortran 77 and later
7657 @item @emph{See also}:
7658 @ref{LGE}, @ref{LGT}, @ref{LLE}
7664 @section @code{LNBLNK} --- Index of the last non-blank character in a string
7666 @cindex string, find non-blank character
7669 @item @emph{Description}:
7670 Returns the length of a character string, ignoring any trailing blanks.
7671 This is identical to the standard @code{LEN_TRIM} intrinsic, and is only
7672 included for backwards compatibility.
7674 @item @emph{Standard}:
7680 @item @emph{Syntax}:
7681 @code{RESULT = LNBLNK(STRING)}
7683 @item @emph{Arguments}:
7684 @multitable @columnfractions .15 .70
7685 @item @var{STRING} @tab Shall be a scalar of type @code{CHARACTER},
7686 with @code{INTENT(IN)}
7689 @item @emph{Return value}:
7690 The return value is of @code{INTEGER(kind=4)} type.
7692 @item @emph{See also}:
7693 @ref{INDEX intrinsic}, @ref{LEN_TRIM}
7699 @section @code{LOC} --- Returns the address of a variable
7701 @cindex location of a variable in memory
7704 @item @emph{Description}:
7705 @code{LOC(X)} returns the address of @var{X} as an integer.
7707 @item @emph{Standard}:
7713 @item @emph{Syntax}:
7714 @code{RESULT = LOC(X)}
7716 @item @emph{Arguments}:
7717 @multitable @columnfractions .15 .70
7718 @item @var{X} @tab Variable of any type.
7721 @item @emph{Return value}:
7722 The return value is of type @code{INTEGER}, with a @code{KIND}
7723 corresponding to the size (in bytes) of a memory address on the target
7726 @item @emph{Example}:
7733 end program test_loc
7740 @section @code{LOG} --- Logarithm function
7747 @cindex exponential function, inverse
7748 @cindex logarithmic function
7751 @item @emph{Description}:
7752 @code{LOG(X)} computes the logarithm of @var{X}.
7754 @item @emph{Standard}:
7755 Fortran 77 and later
7760 @item @emph{Syntax}:
7761 @code{RESULT = LOG(X)}
7763 @item @emph{Arguments}:
7764 @multitable @columnfractions .15 .70
7765 @item @var{X} @tab The type shall be @code{REAL} or
7769 @item @emph{Return value}:
7770 The return value is of type @code{REAL} or @code{COMPLEX}.
7771 The kind type parameter is the same as @var{X}.
7772 If @var{X} is @code{COMPLEX}, the imaginary part @math{\omega} is in the range
7773 @math{-\pi \leq \omega \leq \pi}.
7775 @item @emph{Example}:
7778 real(8) :: x = 1.0_8
7779 complex :: z = (1.0, 2.0)
7782 end program test_log
7785 @item @emph{Specific names}:
7786 @multitable @columnfractions .20 .20 .20 .25
7787 @item Name @tab Argument @tab Return type @tab Standard
7788 @item @code{ALOG(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab f95, gnu
7789 @item @code{DLOG(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab f95, gnu
7790 @item @code{CLOG(X)} @tab @code{COMPLEX(4) X} @tab @code{COMPLEX(4)} @tab f95, gnu
7791 @item @code{ZLOG(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab f95, gnu
7792 @item @code{CDLOG(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab f95, gnu
7799 @section @code{LOG10} --- Base 10 logarithm function
7803 @cindex exponential function, inverse
7804 @cindex logarithmic function
7807 @item @emph{Description}:
7808 @code{LOG10(X)} computes the base 10 logarithm of @var{X}.
7810 @item @emph{Standard}:
7811 Fortran 77 and later
7816 @item @emph{Syntax}:
7817 @code{RESULT = LOG10(X)}
7819 @item @emph{Arguments}:
7820 @multitable @columnfractions .15 .70
7821 @item @var{X} @tab The type shall be @code{REAL}.
7824 @item @emph{Return value}:
7825 The return value is of type @code{REAL} or @code{COMPLEX}.
7826 The kind type parameter is the same as @var{X}.
7828 @item @emph{Example}:
7831 real(8) :: x = 10.0_8
7833 end program test_log10
7836 @item @emph{Specific names}:
7837 @multitable @columnfractions .20 .20 .20 .25
7838 @item Name @tab Argument @tab Return type @tab Standard
7839 @item @code{ALOG10(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 95 and later
7840 @item @code{DLOG10(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 95 and later
7847 @section @code{LOG_GAMMA} --- Logarithm of the Gamma function
7852 @cindex Gamma function, logarithm of
7855 @item @emph{Description}:
7856 @code{LOG_GAMMA(X)} computes the natural logarithm of the absolute value
7857 of the Gamma (@math{\Gamma}) function.
7859 @item @emph{Standard}:
7860 Fortran 2008 and later
7865 @item @emph{Syntax}:
7866 @code{X = LOG_GAMMA(X)}
7868 @item @emph{Arguments}:
7869 @multitable @columnfractions .15 .70
7870 @item @var{X} @tab Shall be of type @code{REAL} and neither zero
7871 nor a negative integer.
7874 @item @emph{Return value}:
7875 The return value is of type @code{REAL} of the same kind as @var{X}.
7877 @item @emph{Example}:
7879 program test_log_gamma
7881 x = lgamma(x) ! returns 0.0
7882 end program test_log_gamma
7885 @item @emph{Specific names}:
7886 @multitable @columnfractions .20 .20 .20 .25
7887 @item Name @tab Argument @tab Return type @tab Standard
7888 @item @code{LGAMMA(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab GNU Extension
7889 @item @code{ALGAMA(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab GNU Extension
7890 @item @code{DLGAMA(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab GNU Extension
7893 @item @emph{See also}:
7894 Gamma function: @ref{GAMMA}
7901 @section @code{LOGICAL} --- Convert to logical type
7903 @cindex conversion, to logical
7906 @item @emph{Description}:
7907 Converts one kind of @code{LOGICAL} variable to another.
7909 @item @emph{Standard}:
7910 Fortran 95 and later
7915 @item @emph{Syntax}:
7916 @code{RESULT = LOGICAL(L [, KIND])}
7918 @item @emph{Arguments}:
7919 @multitable @columnfractions .15 .70
7920 @item @var{L} @tab The type shall be @code{LOGICAL}.
7921 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
7922 expression indicating the kind parameter of the result.
7925 @item @emph{Return value}:
7926 The return value is a @code{LOGICAL} value equal to @var{L}, with a
7927 kind corresponding to @var{KIND}, or of the default logical kind if
7928 @var{KIND} is not given.
7930 @item @emph{See also}:
7931 @ref{INT}, @ref{REAL}, @ref{CMPLX}
7937 @section @code{LONG} --- Convert to integer type
7939 @cindex conversion, to integer
7942 @item @emph{Description}:
7943 Convert to a @code{KIND=4} integer type, which is the same size as a C
7944 @code{long} integer. This is equivalent to the standard @code{INT}
7945 intrinsic with an optional argument of @code{KIND=4}, and is only
7946 included for backwards compatibility.
7948 @item @emph{Standard}:
7954 @item @emph{Syntax}:
7955 @code{RESULT = LONG(A)}
7957 @item @emph{Arguments}:
7958 @multitable @columnfractions .15 .70
7959 @item @var{A} @tab Shall be of type @code{INTEGER},
7960 @code{REAL}, or @code{COMPLEX}.
7963 @item @emph{Return value}:
7964 The return value is a @code{INTEGER(4)} variable.
7966 @item @emph{See also}:
7967 @ref{INT}, @ref{INT2}, @ref{INT8}
7973 @section @code{LSHIFT} --- Left shift bits
7975 @cindex bits, shift left
7978 @item @emph{Description}:
7979 @code{LSHIFT} returns a value corresponding to @var{I} with all of the
7980 bits shifted left by @var{SHIFT} places. If the absolute value of
7981 @var{SHIFT} is greater than @code{BIT_SIZE(I)}, the value is undefined.
7982 Bits shifted out from the left end are lost; zeros are shifted in from
7985 This function has been superseded by the @code{ISHFT} intrinsic, which
7986 is standard in Fortran 95 and later, and the @code{SHIFTL} intrinsic,
7987 which is standard in Fortran 2008 and later.
7989 @item @emph{Standard}:
7995 @item @emph{Syntax}:
7996 @code{RESULT = LSHIFT(I, SHIFT)}
7998 @item @emph{Arguments}:
7999 @multitable @columnfractions .15 .70
8000 @item @var{I} @tab The type shall be @code{INTEGER}.
8001 @item @var{SHIFT} @tab The type shall be @code{INTEGER}.
8004 @item @emph{Return value}:
8005 The return value is of type @code{INTEGER} and of the same kind as
8008 @item @emph{See also}:
8009 @ref{ISHFT}, @ref{ISHFTC}, @ref{RSHIFT}, @ref{SHIFTA}, @ref{SHIFTL},
8017 @section @code{LSTAT} --- Get file status
8019 @cindex file system, file status
8022 @item @emph{Description}:
8023 @code{LSTAT} is identical to @ref{STAT}, except that if path is a
8024 symbolic link, then the link itself is statted, not the file that it
8027 The elements in @code{VALUES} are the same as described by @ref{STAT}.
8029 This intrinsic is provided in both subroutine and function forms;
8030 however, only one form can be used in any given program unit.
8032 @item @emph{Standard}:
8036 Subroutine, function
8038 @item @emph{Syntax}:
8039 @multitable @columnfractions .80
8040 @item @code{CALL LSTAT(NAME, VALUES [, STATUS])}
8041 @item @code{STATUS = LSTAT(NAME, VALUES)}
8044 @item @emph{Arguments}:
8045 @multitable @columnfractions .15 .70
8046 @item @var{NAME} @tab The type shall be @code{CHARACTER} of the default
8047 kind, a valid path within the file system.
8048 @item @var{VALUES} @tab The type shall be @code{INTEGER(4), DIMENSION(13)}.
8049 @item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER(4)}.
8050 Returns 0 on success and a system specific error code otherwise.
8053 @item @emph{Example}:
8054 See @ref{STAT} for an example.
8056 @item @emph{See also}:
8057 To stat an open file: @ref{FSTAT}, to stat a file: @ref{STAT}
8063 @section @code{LTIME} --- Convert time to local time info
8065 @cindex time, conversion to local time info
8068 @item @emph{Description}:
8069 Given a system time value @var{TIME} (as provided by the @code{TIME8()}
8070 intrinsic), fills @var{VALUES} with values extracted from it appropriate
8071 to the local time zone using @code{localtime(3)}.
8073 @item @emph{Standard}:
8079 @item @emph{Syntax}:
8080 @code{CALL LTIME(TIME, VALUES)}
8082 @item @emph{Arguments}:
8083 @multitable @columnfractions .15 .70
8084 @item @var{TIME} @tab An @code{INTEGER} scalar expression
8085 corresponding to a system time, with @code{INTENT(IN)}.
8086 @item @var{VALUES} @tab A default @code{INTEGER} array with 9 elements,
8087 with @code{INTENT(OUT)}.
8090 @item @emph{Return value}:
8091 The elements of @var{VALUES} are assigned as follows:
8093 @item Seconds after the minute, range 0--59 or 0--61 to allow for leap
8095 @item Minutes after the hour, range 0--59
8096 @item Hours past midnight, range 0--23
8097 @item Day of month, range 0--31
8098 @item Number of months since January, range 0--12
8099 @item Years since 1900
8100 @item Number of days since Sunday, range 0--6
8101 @item Days since January 1
8102 @item Daylight savings indicator: positive if daylight savings is in
8103 effect, zero if not, and negative if the information is not available.
8106 @item @emph{See also}:
8107 @ref{CTIME}, @ref{GMTIME}, @ref{TIME}, @ref{TIME8}
8114 @section @code{MALLOC} --- Allocate dynamic memory
8116 @cindex pointer, cray
8119 @item @emph{Description}:
8120 @code{MALLOC(SIZE)} allocates @var{SIZE} bytes of dynamic memory and
8121 returns the address of the allocated memory. The @code{MALLOC} intrinsic
8122 is an extension intended to be used with Cray pointers, and is provided
8123 in GNU Fortran to allow the user to compile legacy code. For new code
8124 using Fortran 95 pointers, the memory allocation intrinsic is
8127 @item @emph{Standard}:
8133 @item @emph{Syntax}:
8134 @code{PTR = MALLOC(SIZE)}
8136 @item @emph{Arguments}:
8137 @multitable @columnfractions .15 .70
8138 @item @var{SIZE} @tab The type shall be @code{INTEGER}.
8141 @item @emph{Return value}:
8142 The return value is of type @code{INTEGER(K)}, with @var{K} such that
8143 variables of type @code{INTEGER(K)} have the same size as
8144 C pointers (@code{sizeof(void *)}).
8146 @item @emph{Example}:
8147 The following example demonstrates the use of @code{MALLOC} and
8148 @code{FREE} with Cray pointers.
8157 ptr_x = malloc(20*8)
8159 x(i) = sqrt(1.0d0 / i)
8167 end program test_malloc
8170 @item @emph{See also}:
8177 @section @code{MASKL} --- Left justified mask
8179 @cindex mask, left justified
8182 @item @emph{Description}:
8183 @code{MASKL(I[, KIND])} has its leftmost @var{I} bits set to 1, and the
8184 remaining bits set to 0.
8186 @item @emph{Standard}:
8187 Fortran 2008 and later
8192 @item @emph{Syntax}:
8193 @code{RESULT = MASKL(I[, KIND])}
8195 @item @emph{Arguments}:
8196 @multitable @columnfractions .15 .70
8197 @item @var{I} @tab Shall be of type @code{INTEGER}.
8198 @item @var{KIND} @tab Shall be a scalar constant expression of type
8202 @item @emph{Return value}:
8203 The return value is of type @code{INTEGER}. If @var{KIND} is present, it
8204 specifies the kind value of the return type; otherwise, it is of the
8205 default integer kind.
8207 @item @emph{See also}:
8214 @section @code{MASKR} --- Right justified mask
8216 @cindex mask, right justified
8219 @item @emph{Description}:
8220 @code{MASKL(I[, KIND])} has its rightmost @var{I} bits set to 1, and the
8221 remaining bits set to 0.
8223 @item @emph{Standard}:
8224 Fortran 2008 and later
8229 @item @emph{Syntax}:
8230 @code{RESULT = MASKR(I[, KIND])}
8232 @item @emph{Arguments}:
8233 @multitable @columnfractions .15 .70
8234 @item @var{I} @tab Shall be of type @code{INTEGER}.
8235 @item @var{KIND} @tab Shall be a scalar constant expression of type
8239 @item @emph{Return value}:
8240 The return value is of type @code{INTEGER}. If @var{KIND} is present, it
8241 specifies the kind value of the return type; otherwise, it is of the
8242 default integer kind.
8244 @item @emph{See also}:
8251 @section @code{MATMUL} --- matrix multiplication
8253 @cindex matrix multiplication
8254 @cindex product, matrix
8257 @item @emph{Description}:
8258 Performs a matrix multiplication on numeric or logical arguments.
8260 @item @emph{Standard}:
8261 Fortran 95 and later
8264 Transformational function
8266 @item @emph{Syntax}:
8267 @code{RESULT = MATMUL(MATRIX_A, MATRIX_B)}
8269 @item @emph{Arguments}:
8270 @multitable @columnfractions .15 .70
8271 @item @var{MATRIX_A} @tab An array of @code{INTEGER},
8272 @code{REAL}, @code{COMPLEX}, or @code{LOGICAL} type, with a rank of
8274 @item @var{MATRIX_B} @tab An array of @code{INTEGER},
8275 @code{REAL}, or @code{COMPLEX} type if @var{MATRIX_A} is of a numeric
8276 type; otherwise, an array of @code{LOGICAL} type. The rank shall be one
8277 or two, and the first (or only) dimension of @var{MATRIX_B} shall be
8278 equal to the last (or only) dimension of @var{MATRIX_A}.
8281 @item @emph{Return value}:
8282 The matrix product of @var{MATRIX_A} and @var{MATRIX_B}. The type and
8283 kind of the result follow the usual type and kind promotion rules, as
8284 for the @code{*} or @code{.AND.} operators.
8286 @item @emph{See also}:
8292 @section @code{MAX} --- Maximum value of an argument list
8299 @cindex maximum value
8302 @item @emph{Description}:
8303 Returns the argument with the largest (most positive) value.
8305 @item @emph{Standard}:
8306 Fortran 77 and later
8311 @item @emph{Syntax}:
8312 @code{RESULT = MAX(A1, A2 [, A3 [, ...]])}
8314 @item @emph{Arguments}:
8315 @multitable @columnfractions .15 .70
8316 @item @var{A1} @tab The type shall be @code{INTEGER} or
8318 @item @var{A2}, @var{A3}, ... @tab An expression of the same type and kind
8319 as @var{A1}. (As a GNU extension, arguments of different kinds are
8323 @item @emph{Return value}:
8324 The return value corresponds to the maximum value among the arguments,
8325 and has the same type and kind as the first argument.
8327 @item @emph{Specific names}:
8328 @multitable @columnfractions .20 .20 .20 .25
8329 @item Name @tab Argument @tab Return type @tab Standard
8330 @item @code{MAX0(A1)} @tab @code{INTEGER(4) A1} @tab @code{INTEGER(4)} @tab Fortran 77 and later
8331 @item @code{AMAX0(A1)} @tab @code{INTEGER(4) A1} @tab @code{REAL(MAX(X))} @tab Fortran 77 and later
8332 @item @code{MAX1(A1)} @tab @code{REAL A1} @tab @code{INT(MAX(X))} @tab Fortran 77 and later
8333 @item @code{AMAX1(A1)} @tab @code{REAL(4) A1} @tab @code{REAL(4)} @tab Fortran 77 and later
8334 @item @code{DMAX1(A1)} @tab @code{REAL(8) A1} @tab @code{REAL(8)} @tab Fortran 77 and later
8337 @item @emph{See also}:
8338 @ref{MAXLOC} @ref{MAXVAL}, @ref{MIN}
8345 @section @code{MAXEXPONENT} --- Maximum exponent of a real kind
8346 @fnindex MAXEXPONENT
8347 @cindex model representation, maximum exponent
8350 @item @emph{Description}:
8351 @code{MAXEXPONENT(X)} returns the maximum exponent in the model of the
8354 @item @emph{Standard}:
8355 Fortran 95 and later
8360 @item @emph{Syntax}:
8361 @code{RESULT = MAXEXPONENT(X)}
8363 @item @emph{Arguments}:
8364 @multitable @columnfractions .15 .70
8365 @item @var{X} @tab Shall be of type @code{REAL}.
8368 @item @emph{Return value}:
8369 The return value is of type @code{INTEGER} and of the default integer
8372 @item @emph{Example}:
8378 print *, minexponent(x), maxexponent(x)
8379 print *, minexponent(y), maxexponent(y)
8380 end program exponents
8387 @section @code{MAXLOC} --- Location of the maximum value within an array
8389 @cindex array, location of maximum element
8392 @item @emph{Description}:
8393 Determines the location of the element in the array with the maximum
8394 value, or, if the @var{DIM} argument is supplied, determines the
8395 locations of the maximum element along each row of the array in the
8396 @var{DIM} direction. If @var{MASK} is present, only the elements for
8397 which @var{MASK} is @code{.TRUE.} are considered. If more than one
8398 element in the array has the maximum value, the location returned is
8399 that of the first such element in array element order. If the array has
8400 zero size, or all of the elements of @var{MASK} are @code{.FALSE.}, then
8401 the result is an array of zeroes. Similarly, if @var{DIM} is supplied
8402 and all of the elements of @var{MASK} along a given row are zero, the
8403 result value for that row is zero.
8405 @item @emph{Standard}:
8406 Fortran 95 and later
8409 Transformational function
8411 @item @emph{Syntax}:
8412 @multitable @columnfractions .80
8413 @item @code{RESULT = MAXLOC(ARRAY, DIM [, MASK])}
8414 @item @code{RESULT = MAXLOC(ARRAY [, MASK])}
8417 @item @emph{Arguments}:
8418 @multitable @columnfractions .15 .70
8419 @item @var{ARRAY} @tab Shall be an array of type @code{INTEGER} or
8421 @item @var{DIM} @tab (Optional) Shall be a scalar of type
8422 @code{INTEGER}, with a value between one and the rank of @var{ARRAY},
8423 inclusive. It may not be an optional dummy argument.
8424 @item @var{MASK} @tab Shall be an array of type @code{LOGICAL},
8425 and conformable with @var{ARRAY}.
8428 @item @emph{Return value}:
8429 If @var{DIM} is absent, the result is a rank-one array with a length
8430 equal to the rank of @var{ARRAY}. If @var{DIM} is present, the result
8431 is an array with a rank one less than the rank of @var{ARRAY}, and a
8432 size corresponding to the size of @var{ARRAY} with the @var{DIM}
8433 dimension removed. If @var{DIM} is present and @var{ARRAY} has a rank
8434 of one, the result is a scalar. In all cases, the result is of default
8435 @code{INTEGER} type.
8437 @item @emph{See also}:
8438 @ref{MAX}, @ref{MAXVAL}
8445 @section @code{MAXVAL} --- Maximum value of an array
8447 @cindex array, maximum value
8448 @cindex maximum value
8451 @item @emph{Description}:
8452 Determines the maximum value of the elements in an array value, or, if
8453 the @var{DIM} argument is supplied, determines the maximum value along
8454 each row of the array in the @var{DIM} direction. If @var{MASK} is
8455 present, only the elements for which @var{MASK} is @code{.TRUE.} are
8456 considered. If the array has zero size, or all of the elements of
8457 @var{MASK} are @code{.FALSE.}, then the result is @code{-HUGE(ARRAY)}
8458 if @var{ARRAY} is numeric, or a string of nulls if @var{ARRAY} is of character
8461 @item @emph{Standard}:
8462 Fortran 95 and later
8465 Transformational function
8467 @item @emph{Syntax}:
8468 @multitable @columnfractions .80
8469 @item @code{RESULT = MAXVAL(ARRAY, DIM [, MASK])}
8470 @item @code{RESULT = MAXVAL(ARRAY [, MASK])}
8473 @item @emph{Arguments}:
8474 @multitable @columnfractions .15 .70
8475 @item @var{ARRAY} @tab Shall be an array of type @code{INTEGER} or
8477 @item @var{DIM} @tab (Optional) Shall be a scalar of type
8478 @code{INTEGER}, with a value between one and the rank of @var{ARRAY},
8479 inclusive. It may not be an optional dummy argument.
8480 @item @var{MASK} @tab Shall be an array of type @code{LOGICAL},
8481 and conformable with @var{ARRAY}.
8484 @item @emph{Return value}:
8485 If @var{DIM} is absent, or if @var{ARRAY} has a rank of one, the result
8486 is a scalar. If @var{DIM} is present, the result is an array with a
8487 rank one less than the rank of @var{ARRAY}, and a size corresponding to
8488 the size of @var{ARRAY} with the @var{DIM} dimension removed. In all
8489 cases, the result is of the same type and kind as @var{ARRAY}.
8491 @item @emph{See also}:
8492 @ref{MAX}, @ref{MAXLOC}
8498 @section @code{MCLOCK} --- Time function
8500 @cindex time, clock ticks
8504 @item @emph{Description}:
8505 Returns the number of clock ticks since the start of the process, based
8506 on the UNIX function @code{clock(3)}.
8508 This intrinsic is not fully portable, such as to systems with 32-bit
8509 @code{INTEGER} types but supporting times wider than 32 bits. Therefore,
8510 the values returned by this intrinsic might be, or become, negative, or
8511 numerically less than previous values, during a single run of the
8514 @item @emph{Standard}:
8520 @item @emph{Syntax}:
8521 @code{RESULT = MCLOCK()}
8523 @item @emph{Return value}:
8524 The return value is a scalar of type @code{INTEGER(4)}, equal to the
8525 number of clock ticks since the start of the process, or @code{-1} if
8526 the system does not support @code{clock(3)}.
8528 @item @emph{See also}:
8529 @ref{CTIME}, @ref{GMTIME}, @ref{LTIME}, @ref{MCLOCK}, @ref{TIME}
8536 @section @code{MCLOCK8} --- Time function (64-bit)
8538 @cindex time, clock ticks
8542 @item @emph{Description}:
8543 Returns the number of clock ticks since the start of the process, based
8544 on the UNIX function @code{clock(3)}.
8546 @emph{Warning:} this intrinsic does not increase the range of the timing
8547 values over that returned by @code{clock(3)}. On a system with a 32-bit
8548 @code{clock(3)}, @code{MCLOCK8()} will return a 32-bit value, even though
8549 it is converted to a 64-bit @code{INTEGER(8)} value. That means
8550 overflows of the 32-bit value can still occur. Therefore, the values
8551 returned by this intrinsic might be or become negative or numerically
8552 less than previous values during a single run of the compiled program.
8554 @item @emph{Standard}:
8560 @item @emph{Syntax}:
8561 @code{RESULT = MCLOCK8()}
8563 @item @emph{Return value}:
8564 The return value is a scalar of type @code{INTEGER(8)}, equal to the
8565 number of clock ticks since the start of the process, or @code{-1} if
8566 the system does not support @code{clock(3)}.
8568 @item @emph{See also}:
8569 @ref{CTIME}, @ref{GMTIME}, @ref{LTIME}, @ref{MCLOCK}, @ref{TIME8}
8576 @section @code{MERGE} --- Merge variables
8578 @cindex array, merge arrays
8579 @cindex array, combine arrays
8582 @item @emph{Description}:
8583 Select values from two arrays according to a logical mask. The result
8584 is equal to @var{TSOURCE} if @var{MASK} is @code{.TRUE.}, or equal to
8585 @var{FSOURCE} if it is @code{.FALSE.}.
8587 @item @emph{Standard}:
8588 Fortran 95 and later
8593 @item @emph{Syntax}:
8594 @code{RESULT = MERGE(TSOURCE, FSOURCE, MASK)}
8596 @item @emph{Arguments}:
8597 @multitable @columnfractions .15 .70
8598 @item @var{TSOURCE} @tab May be of any type.
8599 @item @var{FSOURCE} @tab Shall be of the same type and type parameters
8601 @item @var{MASK} @tab Shall be of type @code{LOGICAL}.
8604 @item @emph{Return value}:
8605 The result is of the same type and type parameters as @var{TSOURCE}.
8612 @section @code{MERGE_BITS} --- Merge of bits under mask
8617 @item @emph{Description}:
8618 @code{MERGE_BITS(I, J, MASK)} merges the bits of @var{I} and @var{J}
8619 as determined by the mask. The i-th bit of the result is equal to the
8620 i-th bit of @var{I} if the i-th bit of @var{MASK} is 1; it is equal to
8621 the i-th bit of @var{J} otherwise.
8623 @item @emph{Standard}:
8624 Fortran 2008 and later
8629 @item @emph{Syntax}:
8630 @code{RESULT = MERGE_BITS(I, J, MASK)}
8632 @item @emph{Arguments}:
8633 @multitable @columnfractions .15 .70
8634 @item @var{I} @tab Shall be of type @code{INTEGER}.
8635 @item @var{J} @tab Shall be of type @code{INTEGER} and of the same
8637 @item @var{MASK} @tab Shall be of type @code{INTEGER} and of the same
8641 @item @emph{Return value}:
8642 The result is of the same type and kind as @var{I}.
8649 @section @code{MIN} --- Minimum value of an argument list
8656 @cindex minimum value
8659 @item @emph{Description}:
8660 Returns the argument with the smallest (most negative) value.
8662 @item @emph{Standard}:
8663 Fortran 77 and later
8668 @item @emph{Syntax}:
8669 @code{RESULT = MIN(A1, A2 [, A3, ...])}
8671 @item @emph{Arguments}:
8672 @multitable @columnfractions .15 .70
8673 @item @var{A1} @tab The type shall be @code{INTEGER} or
8675 @item @var{A2}, @var{A3}, ... @tab An expression of the same type and kind
8676 as @var{A1}. (As a GNU extension, arguments of different kinds are
8680 @item @emph{Return value}:
8681 The return value corresponds to the maximum value among the arguments,
8682 and has the same type and kind as the first argument.
8684 @item @emph{Specific names}:
8685 @multitable @columnfractions .20 .20 .20 .25
8686 @item Name @tab Argument @tab Return type @tab Standard
8687 @item @code{MIN0(A1)} @tab @code{INTEGER(4) A1} @tab @code{INTEGER(4)} @tab Fortran 77 and later
8688 @item @code{AMIN0(A1)} @tab @code{INTEGER(4) A1} @tab @code{REAL(4)} @tab Fortran 77 and later
8689 @item @code{MIN1(A1)} @tab @code{REAL A1} @tab @code{INTEGER(4)} @tab Fortran 77 and later
8690 @item @code{AMIN1(A1)} @tab @code{REAL(4) A1} @tab @code{REAL(4)} @tab Fortran 77 and later
8691 @item @code{DMIN1(A1)} @tab @code{REAL(8) A1} @tab @code{REAL(8)} @tab Fortran 77 and later
8694 @item @emph{See also}:
8695 @ref{MAX}, @ref{MINLOC}, @ref{MINVAL}
8701 @section @code{MINEXPONENT} --- Minimum exponent of a real kind
8702 @fnindex MINEXPONENT
8703 @cindex model representation, minimum exponent
8706 @item @emph{Description}:
8707 @code{MINEXPONENT(X)} returns the minimum exponent in the model of the
8710 @item @emph{Standard}:
8711 Fortran 95 and later
8716 @item @emph{Syntax}:
8717 @code{RESULT = MINEXPONENT(X)}
8719 @item @emph{Arguments}:
8720 @multitable @columnfractions .15 .70
8721 @item @var{X} @tab Shall be of type @code{REAL}.
8724 @item @emph{Return value}:
8725 The return value is of type @code{INTEGER} and of the default integer
8728 @item @emph{Example}:
8729 See @code{MAXEXPONENT} for an example.
8735 @section @code{MINLOC} --- Location of the minimum value within an array
8737 @cindex array, location of minimum element
8740 @item @emph{Description}:
8741 Determines the location of the element in the array with the minimum
8742 value, or, if the @var{DIM} argument is supplied, determines the
8743 locations of the minimum element along each row of the array in the
8744 @var{DIM} direction. If @var{MASK} is present, only the elements for
8745 which @var{MASK} is @code{.TRUE.} are considered. If more than one
8746 element in the array has the minimum value, the location returned is
8747 that of the first such element in array element order. If the array has
8748 zero size, or all of the elements of @var{MASK} are @code{.FALSE.}, then
8749 the result is an array of zeroes. Similarly, if @var{DIM} is supplied
8750 and all of the elements of @var{MASK} along a given row are zero, the
8751 result value for that row is zero.
8753 @item @emph{Standard}:
8754 Fortran 95 and later
8757 Transformational function
8759 @item @emph{Syntax}:
8760 @multitable @columnfractions .80
8761 @item @code{RESULT = MINLOC(ARRAY, DIM [, MASK])}
8762 @item @code{RESULT = MINLOC(ARRAY [, MASK])}
8765 @item @emph{Arguments}:
8766 @multitable @columnfractions .15 .70
8767 @item @var{ARRAY} @tab Shall be an array of type @code{INTEGER} or
8769 @item @var{DIM} @tab (Optional) Shall be a scalar of type
8770 @code{INTEGER}, with a value between one and the rank of @var{ARRAY},
8771 inclusive. It may not be an optional dummy argument.
8772 @item @var{MASK} @tab Shall be an array of type @code{LOGICAL},
8773 and conformable with @var{ARRAY}.
8776 @item @emph{Return value}:
8777 If @var{DIM} is absent, the result is a rank-one array with a length
8778 equal to the rank of @var{ARRAY}. If @var{DIM} is present, the result
8779 is an array with a rank one less than the rank of @var{ARRAY}, and a
8780 size corresponding to the size of @var{ARRAY} with the @var{DIM}
8781 dimension removed. If @var{DIM} is present and @var{ARRAY} has a rank
8782 of one, the result is a scalar. In all cases, the result is of default
8783 @code{INTEGER} type.
8785 @item @emph{See also}:
8786 @ref{MIN}, @ref{MINVAL}
8793 @section @code{MINVAL} --- Minimum value of an array
8795 @cindex array, minimum value
8796 @cindex minimum value
8799 @item @emph{Description}:
8800 Determines the minimum value of the elements in an array value, or, if
8801 the @var{DIM} argument is supplied, determines the minimum value along
8802 each row of the array in the @var{DIM} direction. If @var{MASK} is
8803 present, only the elements for which @var{MASK} is @code{.TRUE.} are
8804 considered. If the array has zero size, or all of the elements of
8805 @var{MASK} are @code{.FALSE.}, then the result is @code{HUGE(ARRAY)} if
8806 @var{ARRAY} is numeric, or a string of @code{CHAR(255)} characters if
8807 @var{ARRAY} is of character type.
8809 @item @emph{Standard}:
8810 Fortran 95 and later
8813 Transformational function
8815 @item @emph{Syntax}:
8816 @multitable @columnfractions .80
8817 @item @code{RESULT = MINVAL(ARRAY, DIM [, MASK])}
8818 @item @code{RESULT = MINVAL(ARRAY [, MASK])}
8821 @item @emph{Arguments}:
8822 @multitable @columnfractions .15 .70
8823 @item @var{ARRAY} @tab Shall be an array of type @code{INTEGER} or
8825 @item @var{DIM} @tab (Optional) Shall be a scalar of type
8826 @code{INTEGER}, with a value between one and the rank of @var{ARRAY},
8827 inclusive. It may not be an optional dummy argument.
8828 @item @var{MASK} @tab Shall be an array of type @code{LOGICAL},
8829 and conformable with @var{ARRAY}.
8832 @item @emph{Return value}:
8833 If @var{DIM} is absent, or if @var{ARRAY} has a rank of one, the result
8834 is a scalar. If @var{DIM} is present, the result is an array with a
8835 rank one less than the rank of @var{ARRAY}, and a size corresponding to
8836 the size of @var{ARRAY} with the @var{DIM} dimension removed. In all
8837 cases, the result is of the same type and kind as @var{ARRAY}.
8839 @item @emph{See also}:
8840 @ref{MIN}, @ref{MINLOC}
8847 @section @code{MOD} --- Remainder function
8852 @cindex division, remainder
8855 @item @emph{Description}:
8856 @code{MOD(A,P)} computes the remainder of the division of A by P@. It is
8857 calculated as @code{A - (INT(A/P) * P)}.
8859 @item @emph{Standard}:
8860 Fortran 77 and later
8865 @item @emph{Syntax}:
8866 @code{RESULT = MOD(A, P)}
8868 @item @emph{Arguments}:
8869 @multitable @columnfractions .15 .70
8870 @item @var{A} @tab Shall be a scalar of type @code{INTEGER} or @code{REAL}
8871 @item @var{P} @tab Shall be a scalar of the same type as @var{A} and not
8875 @item @emph{Return value}:
8876 The kind of the return value is the result of cross-promoting
8877 the kinds of the arguments.
8879 @item @emph{Example}:
8883 print *, mod(17.5,5.5)
8884 print *, mod(17.5d0,5.5)
8885 print *, mod(17.5,5.5d0)
8888 print *, mod(-17.5,5.5)
8889 print *, mod(-17.5d0,5.5)
8890 print *, mod(-17.5,5.5d0)
8893 print *, mod(17.5,-5.5)
8894 print *, mod(17.5d0,-5.5)
8895 print *, mod(17.5,-5.5d0)
8896 end program test_mod
8899 @item @emph{Specific names}:
8900 @multitable @columnfractions .20 .20 .20 .25
8901 @item Name @tab Arguments @tab Return type @tab Standard
8902 @item @code{MOD(A,P)} @tab @code{INTEGER A,P} @tab @code{INTEGER} @tab Fortran 95 and later
8903 @item @code{AMOD(A,P)} @tab @code{REAL(4) A,P} @tab @code{REAL(4)} @tab Fortran 95 and later
8904 @item @code{DMOD(A,P)} @tab @code{REAL(8) A,P} @tab @code{REAL(8)} @tab Fortran 95 and later
8911 @section @code{MODULO} --- Modulo function
8914 @cindex division, modulo
8917 @item @emph{Description}:
8918 @code{MODULO(A,P)} computes the @var{A} modulo @var{P}.
8920 @item @emph{Standard}:
8921 Fortran 95 and later
8926 @item @emph{Syntax}:
8927 @code{RESULT = MODULO(A, P)}
8929 @item @emph{Arguments}:
8930 @multitable @columnfractions .15 .70
8931 @item @var{A} @tab Shall be a scalar of type @code{INTEGER} or @code{REAL}
8932 @item @var{P} @tab Shall be a scalar of the same type and kind as @var{A}
8935 @item @emph{Return value}:
8936 The type and kind of the result are those of the arguments.
8938 @item If @var{A} and @var{P} are of type @code{INTEGER}:
8939 @code{MODULO(A,P)} has the value @var{R} such that @code{A=Q*P+R}, where
8940 @var{Q} is an integer and @var{R} is between 0 (inclusive) and @var{P}
8942 @item If @var{A} and @var{P} are of type @code{REAL}:
8943 @code{MODULO(A,P)} has the value of @code{A - FLOOR (A / P) * P}.
8945 In all cases, if @var{P} is zero the result is processor-dependent.
8947 @item @emph{Example}:
8950 print *, modulo(17,3)
8951 print *, modulo(17.5,5.5)
8953 print *, modulo(-17,3)
8954 print *, modulo(-17.5,5.5)
8956 print *, modulo(17,-3)
8957 print *, modulo(17.5,-5.5)
8966 @section @code{MOVE_ALLOC} --- Move allocation from one object to another
8968 @cindex moving allocation
8969 @cindex allocation, moving
8972 @item @emph{Description}:
8973 @code{MOVE_ALLOC(FROM, TO)} moves the allocation from @var{FROM} to
8974 @var{TO}. @var{FROM} will become deallocated in the process.
8976 @item @emph{Standard}:
8977 Fortran 2003 and later
8982 @item @emph{Syntax}:
8983 @code{CALL MOVE_ALLOC(FROM, TO)}
8985 @item @emph{Arguments}:
8986 @multitable @columnfractions .15 .70
8987 @item @var{FROM} @tab @code{ALLOCATABLE}, @code{INTENT(INOUT)}, may be
8988 of any type and kind.
8989 @item @var{TO} @tab @code{ALLOCATABLE}, @code{INTENT(OUT)}, shall be
8990 of the same type, kind and rank as @var{FROM}.
8993 @item @emph{Return value}:
8996 @item @emph{Example}:
8998 program test_move_alloc
8999 integer, allocatable :: a(:), b(:)
9003 call move_alloc(a, b)
9004 print *, allocated(a), allocated(b)
9006 end program test_move_alloc
9013 @section @code{MVBITS} --- Move bits from one integer to another
9018 @item @emph{Description}:
9019 Moves @var{LEN} bits from positions @var{FROMPOS} through
9020 @code{FROMPOS+LEN-1} of @var{FROM} to positions @var{TOPOS} through
9021 @code{TOPOS+LEN-1} of @var{TO}. The portion of argument @var{TO} not
9022 affected by the movement of bits is unchanged. The values of
9023 @code{FROMPOS+LEN-1} and @code{TOPOS+LEN-1} must be less than
9024 @code{BIT_SIZE(FROM)}.
9026 @item @emph{Standard}:
9027 Fortran 95 and later
9030 Elemental subroutine
9032 @item @emph{Syntax}:
9033 @code{CALL MVBITS(FROM, FROMPOS, LEN, TO, TOPOS)}
9035 @item @emph{Arguments}:
9036 @multitable @columnfractions .15 .70
9037 @item @var{FROM} @tab The type shall be @code{INTEGER}.
9038 @item @var{FROMPOS} @tab The type shall be @code{INTEGER}.
9039 @item @var{LEN} @tab The type shall be @code{INTEGER}.
9040 @item @var{TO} @tab The type shall be @code{INTEGER}, of the
9041 same kind as @var{FROM}.
9042 @item @var{TOPOS} @tab The type shall be @code{INTEGER}.
9045 @item @emph{See also}:
9046 @ref{IBCLR}, @ref{IBSET}, @ref{IBITS}, @ref{IAND}, @ref{IOR}, @ref{IEOR}
9052 @section @code{NEAREST} --- Nearest representable number
9054 @cindex real number, nearest different
9055 @cindex floating point, nearest different
9058 @item @emph{Description}:
9059 @code{NEAREST(X, S)} returns the processor-representable number nearest
9060 to @code{X} in the direction indicated by the sign of @code{S}.
9062 @item @emph{Standard}:
9063 Fortran 95 and later
9068 @item @emph{Syntax}:
9069 @code{RESULT = NEAREST(X, S)}
9071 @item @emph{Arguments}:
9072 @multitable @columnfractions .15 .70
9073 @item @var{X} @tab Shall be of type @code{REAL}.
9074 @item @var{S} @tab (Optional) shall be of type @code{REAL} and
9078 @item @emph{Return value}:
9079 The return value is of the same type as @code{X}. If @code{S} is
9080 positive, @code{NEAREST} returns the processor-representable number
9081 greater than @code{X} and nearest to it. If @code{S} is negative,
9082 @code{NEAREST} returns the processor-representable number smaller than
9083 @code{X} and nearest to it.
9085 @item @emph{Example}:
9087 program test_nearest
9089 x = nearest(42.0, 1.0)
9090 y = nearest(42.0, -1.0)
9091 write (*,"(3(G20.15))") x, y, x - y
9092 end program test_nearest
9099 @section @code{NEW_LINE} --- New line character
9102 @cindex output, newline
9105 @item @emph{Description}:
9106 @code{NEW_LINE(C)} returns the new-line character.
9108 @item @emph{Standard}:
9109 Fortran 2003 and later
9114 @item @emph{Syntax}:
9115 @code{RESULT = NEW_LINE(C)}
9117 @item @emph{Arguments}:
9118 @multitable @columnfractions .15 .70
9119 @item @var{C} @tab The argument shall be a scalar or array of the
9120 type @code{CHARACTER}.
9123 @item @emph{Return value}:
9124 Returns a @var{CHARACTER} scalar of length one with the new-line character of
9125 the same kind as parameter @var{C}.
9127 @item @emph{Example}:
9131 write(*,'(A)') 'This is record 1.'//NEW_LINE('A')//'This is record 2.'
9139 @section @code{NINT} --- Nearest whole number
9142 @cindex rounding, nearest whole number
9145 @item @emph{Description}:
9146 @code{NINT(A)} rounds its argument to the nearest whole number.
9148 @item @emph{Standard}:
9149 Fortran 77 and later, with @var{KIND} argument Fortran 90 and later
9154 @item @emph{Syntax}:
9155 @code{RESULT = NINT(A [, KIND])}
9157 @item @emph{Arguments}:
9158 @multitable @columnfractions .15 .70
9159 @item @var{A} @tab The type of the argument shall be @code{REAL}.
9160 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
9161 expression indicating the kind parameter of the result.
9164 @item @emph{Return value}:
9165 Returns @var{A} with the fractional portion of its magnitude eliminated by
9166 rounding to the nearest whole number and with its sign preserved,
9167 converted to an @code{INTEGER} of the default kind.
9169 @item @emph{Example}:
9176 print *, nint(x4), idnint(x8)
9177 end program test_nint
9180 @item @emph{Specific names}:
9181 @multitable @columnfractions .20 .20 .20 .25
9182 @item Name @tab Argument @tab Return Type @tab Standard
9183 @item @code{NINT(A)} @tab @code{REAL(4) A} @tab @code{INTEGER} @tab Fortran 95 and later
9184 @item @code{IDNINT(A)} @tab @code{REAL(8) A} @tab @code{INTEGER} @tab Fortran 95 and later
9187 @item @emph{See also}:
9188 @ref{CEILING}, @ref{FLOOR}
9195 @section @code{NORM2} --- Euclidean vector norms
9197 @cindex Euclidean vector norm
9198 @cindex L2 vector norm
9199 @cindex norm, Euclidean
9202 @item @emph{Description}:
9203 Calculates the Euclidean vector norm (@math{L_2} norm) of
9204 of @var{ARRAY} along dimension @var{DIM}.
9206 @item @emph{Standard}:
9207 Fortran 2008 and later
9210 Transformational function
9212 @item @emph{Syntax}:
9213 @multitable @columnfractions .80
9214 @item @code{RESULT = NORM2(ARRAY[, DIM])}
9217 @item @emph{Arguments}:
9218 @multitable @columnfractions .15 .70
9219 @item @var{ARRAY} @tab Shall be an array of type @code{REAL}
9220 @item @var{DIM} @tab (Optional) shall be a scalar of type
9221 @code{INTEGER} with a value in the range from 1 to n, where n
9222 equals the rank of @var{ARRAY}.
9225 @item @emph{Return value}:
9226 The result is of the same type as @var{ARRAY}.
9228 If @var{DIM} is absent, a scalar with the square root of the sum of all
9229 elements in @var{ARRAY} squared is returned. Otherwise, an array of
9230 rank @math{n-1}, where @math{n} equals the rank of @var{ARRAY}, and a
9231 shape similar to that of @var{ARRAY} with dimension @var{DIM} dropped
9234 @item @emph{Example}:
9237 REAL :: x(5) = [ real :: 1, 2, 3, 4, 5 ]
9238 print *, NORM2(x) ! = sqrt(55.) ~ 7.416
9246 @section @code{NOT} --- Logical negation
9248 @cindex bits, negate
9249 @cindex bitwise logical not
9250 @cindex logical not, bitwise
9253 @item @emph{Description}:
9254 @code{NOT} returns the bitwise Boolean inverse of @var{I}.
9256 @item @emph{Standard}:
9257 Fortran 95 and later
9262 @item @emph{Syntax}:
9263 @code{RESULT = NOT(I)}
9265 @item @emph{Arguments}:
9266 @multitable @columnfractions .15 .70
9267 @item @var{I} @tab The type shall be @code{INTEGER}.
9270 @item @emph{Return value}:
9271 The return type is @code{INTEGER}, of the same kind as the
9274 @item @emph{See also}:
9275 @ref{IAND}, @ref{IEOR}, @ref{IOR}, @ref{IBITS}, @ref{IBSET}, @ref{IBCLR}
9282 @section @code{NULL} --- Function that returns an disassociated pointer
9284 @cindex pointer, status
9285 @cindex pointer, disassociated
9288 @item @emph{Description}:
9289 Returns a disassociated pointer.
9291 If @var{MOLD} is present, a disassociated pointer of the same type is
9292 returned, otherwise the type is determined by context.
9294 In Fortran 95, @var{MOLD} is optional. Please note that Fortran 2003
9295 includes cases where it is required.
9297 @item @emph{Standard}:
9298 Fortran 95 and later
9301 Transformational function
9303 @item @emph{Syntax}:
9304 @code{PTR => NULL([MOLD])}
9306 @item @emph{Arguments}:
9307 @multitable @columnfractions .15 .70
9308 @item @var{MOLD} @tab (Optional) shall be a pointer of any association
9309 status and of any type.
9312 @item @emph{Return value}:
9313 A disassociated pointer.
9315 @item @emph{Example}:
9317 REAL, POINTER, DIMENSION(:) :: VEC => NULL ()
9320 @item @emph{See also}:
9327 @section @code{NUM_IMAGES} --- Function that returns the number of images
9329 @cindex coarray, @code{NUM_IMAGES}
9330 @cindex images, number of
9333 @item @emph{Description}:
9334 Returns the number of images.
9336 @item @emph{Standard}:
9337 Fortran 2008 and later
9340 Transformational function
9342 @item @emph{Syntax}:
9343 @code{RESULT = NUM_IMAGES()}
9345 @item @emph{Arguments}: None.
9347 @item @emph{Return value}:
9348 Scalar default-kind integer.
9350 @item @emph{Example}:
9354 value = THIS_IMAGE()
9356 IF (THIS_IMAGE() == 1) THEN
9357 DO i = 1, NUM_IMAGES()
9358 WRITE(*,'(2(a,i0))') 'value[', i, '] is ', value[i]
9363 @item @emph{See also}:
9364 @ref{THIS_IMAGE}, @ref{IMAGE_INDEX}
9370 @section @code{OR} --- Bitwise logical OR
9372 @cindex bitwise logical or
9373 @cindex logical or, bitwise
9376 @item @emph{Description}:
9377 Bitwise logical @code{OR}.
9379 This intrinsic routine is provided for backwards compatibility with
9380 GNU Fortran 77. For integer arguments, programmers should consider
9381 the use of the @ref{IOR} intrinsic defined by the Fortran standard.
9383 @item @emph{Standard}:
9389 @item @emph{Syntax}:
9390 @code{RESULT = OR(I, J)}
9392 @item @emph{Arguments}:
9393 @multitable @columnfractions .15 .70
9394 @item @var{I} @tab The type shall be either a scalar @code{INTEGER}
9395 type or a scalar @code{LOGICAL} type.
9396 @item @var{J} @tab The type shall be the same as the type of @var{J}.
9399 @item @emph{Return value}:
9400 The return type is either a scalar @code{INTEGER} or a scalar
9401 @code{LOGICAL}. If the kind type parameters differ, then the
9402 smaller kind type is implicitly converted to larger kind, and the
9403 return has the larger kind.
9405 @item @emph{Example}:
9408 LOGICAL :: T = .TRUE., F = .FALSE.
9410 DATA a / Z'F' /, b / Z'3' /
9412 WRITE (*,*) OR(T, T), OR(T, F), OR(F, T), OR(F, F)
9413 WRITE (*,*) OR(a, b)
9417 @item @emph{See also}:
9418 Fortran 95 elemental function: @ref{IOR}
9424 @section @code{PACK} --- Pack an array into an array of rank one
9426 @cindex array, packing
9427 @cindex array, reduce dimension
9428 @cindex array, gather elements
9431 @item @emph{Description}:
9432 Stores the elements of @var{ARRAY} in an array of rank one.
9434 The beginning of the resulting array is made up of elements whose @var{MASK}
9435 equals @code{TRUE}. Afterwards, positions are filled with elements taken from
9438 @item @emph{Standard}:
9439 Fortran 95 and later
9442 Transformational function
9444 @item @emph{Syntax}:
9445 @code{RESULT = PACK(ARRAY, MASK[,VECTOR]}
9447 @item @emph{Arguments}:
9448 @multitable @columnfractions .15 .70
9449 @item @var{ARRAY} @tab Shall be an array of any type.
9450 @item @var{MASK} @tab Shall be an array of type @code{LOGICAL} and
9451 of the same size as @var{ARRAY}. Alternatively, it may be a @code{LOGICAL}
9453 @item @var{VECTOR} @tab (Optional) shall be an array of the same type
9454 as @var{ARRAY} and of rank one. If present, the number of elements in
9455 @var{VECTOR} shall be equal to or greater than the number of true elements
9456 in @var{MASK}. If @var{MASK} is scalar, the number of elements in
9457 @var{VECTOR} shall be equal to or greater than the number of elements in
9461 @item @emph{Return value}:
9462 The result is an array of rank one and the same type as that of @var{ARRAY}.
9463 If @var{VECTOR} is present, the result size is that of @var{VECTOR}, the
9464 number of @code{TRUE} values in @var{MASK} otherwise.
9466 @item @emph{Example}:
9467 Gathering nonzero elements from an array:
9471 m = (/ 1, 0, 0, 0, 5, 0 /)
9472 WRITE(*, FMT="(6(I0, ' '))") pack(m, m /= 0) ! "1 5"
9476 Gathering nonzero elements from an array and appending elements from @var{VECTOR}:
9480 m = (/ 1, 0, 0, 2 /)
9481 WRITE(*, FMT="(4(I0, ' '))") pack(m, m /= 0, (/ 0, 0, 3, 4 /)) ! "1 2 3 4"
9485 @item @emph{See also}:
9492 @section @code{PARITY} --- Reduction with exclusive OR
9495 @cindex Reduction, XOR
9496 @cindex XOR reduction
9499 @item @emph{Description}:
9500 Calculates the parity, i.e. the reduction using @code{.XOR.},
9501 of @var{MASK} along dimension @var{DIM}.
9503 @item @emph{Standard}:
9504 Fortran 2008 and later
9507 Transformational function
9509 @item @emph{Syntax}:
9510 @multitable @columnfractions .80
9511 @item @code{RESULT = PARITY(MASK[, DIM])}
9514 @item @emph{Arguments}:
9515 @multitable @columnfractions .15 .70
9516 @item @var{LOGICAL} @tab Shall be an array of type @code{LOGICAL}
9517 @item @var{DIM} @tab (Optional) shall be a scalar of type
9518 @code{INTEGER} with a value in the range from 1 to n, where n
9519 equals the rank of @var{MASK}.
9522 @item @emph{Return value}:
9523 The result is of the same type as @var{MASK}.
9525 If @var{DIM} is absent, a scalar with the parity of all elements in
9526 @var{MASK} is returned, i.e. true if an odd number of elements is
9527 @code{.true.} and false otherwise. If @var{DIM} is present, an array
9528 of rank @math{n-1}, where @math{n} equals the rank of @var{ARRAY},
9529 and a shape similar to that of @var{MASK} with dimension @var{DIM}
9530 dropped is returned.
9532 @item @emph{Example}:
9535 LOGICAL :: x(2) = [ .true., .false. ]
9536 print *, PARITY(x) ! prints "T" (true).
9544 @section @code{PERROR} --- Print system error message
9546 @cindex system, error handling
9549 @item @emph{Description}:
9550 Prints (on the C @code{stderr} stream) a newline-terminated error
9551 message corresponding to the last system error. This is prefixed by
9552 @var{STRING}, a colon and a space. See @code{perror(3)}.
9554 @item @emph{Standard}:
9560 @item @emph{Syntax}:
9561 @code{CALL PERROR(STRING)}
9563 @item @emph{Arguments}:
9564 @multitable @columnfractions .15 .70
9565 @item @var{STRING} @tab A scalar of type @code{CHARACTER} and of the
9569 @item @emph{See also}:
9576 @section @code{PRECISION} --- Decimal precision of a real kind
9578 @cindex model representation, precision
9581 @item @emph{Description}:
9582 @code{PRECISION(X)} returns the decimal precision in the model of the
9585 @item @emph{Standard}:
9586 Fortran 95 and later
9591 @item @emph{Syntax}:
9592 @code{RESULT = PRECISION(X)}
9594 @item @emph{Arguments}:
9595 @multitable @columnfractions .15 .70
9596 @item @var{X} @tab Shall be of type @code{REAL} or @code{COMPLEX}.
9599 @item @emph{Return value}:
9600 The return value is of type @code{INTEGER} and of the default integer
9603 @item @emph{See also}:
9604 @ref{SELECTED_REAL_KIND}, @ref{RANGE}
9606 @item @emph{Example}:
9608 program prec_and_range
9609 real(kind=4) :: x(2)
9610 complex(kind=8) :: y
9612 print *, precision(x), range(x)
9613 print *, precision(y), range(y)
9614 end program prec_and_range
9621 @section @code{POPCNT} --- Number of bits set
9623 @cindex binary representation
9627 @item @emph{Description}:
9628 @code{POPCNT(I)} returns the number of bits set ('1' bits) in the binary
9629 representation of @code{I}.
9631 @item @emph{Standard}:
9632 Fortran 2008 and later
9637 @item @emph{Syntax}:
9638 @code{RESULT = POPCNT(I)}
9640 @item @emph{Arguments}:
9641 @multitable @columnfractions .15 .70
9642 @item @var{I} @tab Shall be of type @code{INTEGER}.
9645 @item @emph{Return value}:
9646 The return value is of type @code{INTEGER} and of the default integer
9649 @item @emph{See also}:
9650 @ref{POPPAR}, @ref{LEADZ}, @ref{TRAILZ}
9652 @item @emph{Example}:
9654 program test_population
9655 print *, popcnt(127), poppar(127)
9656 print *, popcnt(huge(0_4)), poppar(huge(0_4))
9657 print *, popcnt(huge(0_8)), poppar(huge(0_8))
9658 end program test_population
9664 @section @code{POPPAR} --- Parity of the number of bits set
9666 @cindex binary representation
9670 @item @emph{Description}:
9671 @code{POPPAR(I)} returns parity of the integer @code{I}, i.e. the parity
9672 of the number of bits set ('1' bits) in the binary representation of
9673 @code{I}. It is equal to 0 if @code{I} has an even number of bits set,
9674 and 1 for an odd number of '1' bits.
9676 @item @emph{Standard}:
9677 Fortran 2008 and later
9682 @item @emph{Syntax}:
9683 @code{RESULT = POPPAR(I)}
9685 @item @emph{Arguments}:
9686 @multitable @columnfractions .15 .70
9687 @item @var{I} @tab Shall be of type @code{INTEGER}.
9690 @item @emph{Return value}:
9691 The return value is of type @code{INTEGER} and of the default integer
9694 @item @emph{See also}:
9695 @ref{POPCNT}, @ref{LEADZ}, @ref{TRAILZ}
9697 @item @emph{Example}:
9699 program test_population
9700 print *, popcnt(127), poppar(127)
9701 print *, popcnt(huge(0_4)), poppar(huge(0_4))
9702 print *, popcnt(huge(0_8)), poppar(huge(0_8))
9703 end program test_population
9710 @section @code{PRESENT} --- Determine whether an optional dummy argument is specified
9714 @item @emph{Description}:
9715 Determines whether an optional dummy argument is present.
9717 @item @emph{Standard}:
9718 Fortran 95 and later
9723 @item @emph{Syntax}:
9724 @code{RESULT = PRESENT(A)}
9726 @item @emph{Arguments}:
9727 @multitable @columnfractions .15 .70
9728 @item @var{A} @tab May be of any type and may be a pointer, scalar or array
9729 value, or a dummy procedure. It shall be the name of an optional dummy argument
9730 accessible within the current subroutine or function.
9733 @item @emph{Return value}:
9734 Returns either @code{TRUE} if the optional argument @var{A} is present, or
9735 @code{FALSE} otherwise.
9737 @item @emph{Example}:
9739 PROGRAM test_present
9740 WRITE(*,*) f(), f(42) ! "F T"
9742 LOGICAL FUNCTION f(x)
9743 INTEGER, INTENT(IN), OPTIONAL :: x
9753 @section @code{PRODUCT} --- Product of array elements
9755 @cindex array, product
9756 @cindex array, multiply elements
9757 @cindex array, conditionally multiply elements
9758 @cindex multiply array elements
9761 @item @emph{Description}:
9762 Multiplies the elements of @var{ARRAY} along dimension @var{DIM} if
9763 the corresponding element in @var{MASK} is @code{TRUE}.
9765 @item @emph{Standard}:
9766 Fortran 95 and later
9769 Transformational function
9771 @item @emph{Syntax}:
9772 @multitable @columnfractions .80
9773 @item @code{RESULT = PRODUCT(ARRAY[, MASK])}
9774 @item @code{RESULT = PRODUCT(ARRAY, DIM[, MASK])}
9777 @item @emph{Arguments}:
9778 @multitable @columnfractions .15 .70
9779 @item @var{ARRAY} @tab Shall be an array of type @code{INTEGER},
9780 @code{REAL} or @code{COMPLEX}.
9781 @item @var{DIM} @tab (Optional) shall be a scalar of type
9782 @code{INTEGER} with a value in the range from 1 to n, where n
9783 equals the rank of @var{ARRAY}.
9784 @item @var{MASK} @tab (Optional) shall be of type @code{LOGICAL}
9785 and either be a scalar or an array of the same shape as @var{ARRAY}.
9788 @item @emph{Return value}:
9789 The result is of the same type as @var{ARRAY}.
9791 If @var{DIM} is absent, a scalar with the product of all elements in
9792 @var{ARRAY} is returned. Otherwise, an array of rank n-1, where n equals
9793 the rank of @var{ARRAY}, and a shape similar to that of @var{ARRAY} with
9794 dimension @var{DIM} dropped is returned.
9797 @item @emph{Example}:
9799 PROGRAM test_product
9800 INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /)
9801 print *, PRODUCT(x) ! all elements, product = 120
9802 print *, PRODUCT(x, MASK=MOD(x, 2)==1) ! odd elements, product = 15
9806 @item @emph{See also}:
9813 @section @code{RADIX} --- Base of a model number
9815 @cindex model representation, base
9816 @cindex model representation, radix
9819 @item @emph{Description}:
9820 @code{RADIX(X)} returns the base of the model representing the entity @var{X}.
9822 @item @emph{Standard}:
9823 Fortran 95 and later
9828 @item @emph{Syntax}:
9829 @code{RESULT = RADIX(X)}
9831 @item @emph{Arguments}:
9832 @multitable @columnfractions .15 .70
9833 @item @var{X} @tab Shall be of type @code{INTEGER} or @code{REAL}
9836 @item @emph{Return value}:
9837 The return value is a scalar of type @code{INTEGER} and of the default
9840 @item @emph{See also}:
9841 @ref{SELECTED_REAL_KIND}
9843 @item @emph{Example}:
9846 print *, "The radix for the default integer kind is", radix(0)
9847 print *, "The radix for the default real kind is", radix(0.0)
9848 end program test_radix
9856 @section @code{RAN} --- Real pseudo-random number
9858 @cindex random number generation
9861 @item @emph{Description}:
9862 For compatibility with HP FORTRAN 77/iX, the @code{RAN} intrinsic is
9863 provided as an alias for @code{RAND}. See @ref{RAND} for complete
9866 @item @emph{Standard}:
9872 @item @emph{See also}:
9873 @ref{RAND}, @ref{RANDOM_NUMBER}
9879 @section @code{RAND} --- Real pseudo-random number
9881 @cindex random number generation
9884 @item @emph{Description}:
9885 @code{RAND(FLAG)} returns a pseudo-random number from a uniform
9886 distribution between 0 and 1. If @var{FLAG} is 0, the next number
9887 in the current sequence is returned; if @var{FLAG} is 1, the generator
9888 is restarted by @code{CALL SRAND(0)}; if @var{FLAG} has any other value,
9889 it is used as a new seed with @code{SRAND}.
9891 This intrinsic routine is provided for backwards compatibility with
9892 GNU Fortran 77. It implements a simple modulo generator as provided
9893 by @command{g77}. For new code, one should consider the use of
9894 @ref{RANDOM_NUMBER} as it implements a superior algorithm.
9896 @item @emph{Standard}:
9902 @item @emph{Syntax}:
9903 @code{RESULT = RAND(I)}
9905 @item @emph{Arguments}:
9906 @multitable @columnfractions .15 .70
9907 @item @var{I} @tab Shall be a scalar @code{INTEGER} of kind 4.
9910 @item @emph{Return value}:
9911 The return value is of @code{REAL} type and the default kind.
9913 @item @emph{Example}:
9916 integer,parameter :: seed = 86456
9919 print *, rand(), rand(), rand(), rand()
9920 print *, rand(seed), rand(), rand(), rand()
9921 end program test_rand
9924 @item @emph{See also}:
9925 @ref{SRAND}, @ref{RANDOM_NUMBER}
9932 @section @code{RANDOM_NUMBER} --- Pseudo-random number
9933 @fnindex RANDOM_NUMBER
9934 @cindex random number generation
9937 @item @emph{Description}:
9938 Returns a single pseudorandom number or an array of pseudorandom numbers
9939 from the uniform distribution over the range @math{ 0 \leq x < 1}.
9941 The runtime-library implements George Marsaglia's KISS (Keep It Simple
9942 Stupid) random number generator (RNG). This RNG combines:
9944 @item The congruential generator @math{x(n) = 69069 \cdot x(n-1) + 1327217885}
9945 with a period of @math{2^{32}},
9946 @item A 3-shift shift-register generator with a period of @math{2^{32} - 1},
9947 @item Two 16-bit multiply-with-carry generators with a period of
9948 @math{597273182964842497 > 2^{59}}.
9950 The overall period exceeds @math{2^{123}}.
9952 Please note, this RNG is thread safe if used within OpenMP directives,
9953 i.e., its state will be consistent while called from multiple threads.
9954 However, the KISS generator does not create random numbers in parallel
9955 from multiple sources, but in sequence from a single source. If an
9956 OpenMP-enabled application heavily relies on random numbers, one should
9957 consider employing a dedicated parallel random number generator instead.
9959 @item @emph{Standard}:
9960 Fortran 95 and later
9965 @item @emph{Syntax}:
9966 @code{RANDOM_NUMBER(HARVEST)}
9968 @item @emph{Arguments}:
9969 @multitable @columnfractions .15 .70
9970 @item @var{HARVEST} @tab Shall be a scalar or an array of type @code{REAL}.
9973 @item @emph{Example}:
9975 program test_random_number
9977 CALL init_random_seed() ! see example of RANDOM_SEED
9978 CALL RANDOM_NUMBER(r)
9982 @item @emph{See also}:
9989 @section @code{RANDOM_SEED} --- Initialize a pseudo-random number sequence
9990 @fnindex RANDOM_SEED
9991 @cindex random number generation, seeding
9992 @cindex seeding a random number generator
9995 @item @emph{Description}:
9996 Restarts or queries the state of the pseudorandom number generator used by
9997 @code{RANDOM_NUMBER}.
9999 If @code{RANDOM_SEED} is called without arguments, it is initialized to
10000 a default state. The example below shows how to initialize the random
10001 seed based on the system's time.
10003 @item @emph{Standard}:
10004 Fortran 95 and later
10006 @item @emph{Class}:
10009 @item @emph{Syntax}:
10010 @code{CALL RANDOM_SEED([SIZE, PUT, GET])}
10012 @item @emph{Arguments}:
10013 @multitable @columnfractions .15 .70
10014 @item @var{SIZE} @tab (Optional) Shall be a scalar and of type default
10015 @code{INTEGER}, with @code{INTENT(OUT)}. It specifies the minimum size
10016 of the arrays used with the @var{PUT} and @var{GET} arguments.
10017 @item @var{PUT} @tab (Optional) Shall be an array of type default
10018 @code{INTEGER} and rank one. It is @code{INTENT(IN)} and the size of
10019 the array must be larger than or equal to the number returned by the
10020 @var{SIZE} argument.
10021 @item @var{GET} @tab (Optional) Shall be an array of type default
10022 @code{INTEGER} and rank one. It is @code{INTENT(OUT)} and the size
10023 of the array must be larger than or equal to the number returned by
10024 the @var{SIZE} argument.
10027 @item @emph{Example}:
10029 SUBROUTINE init_random_seed()
10030 INTEGER :: i, n, clock
10031 INTEGER, DIMENSION(:), ALLOCATABLE :: seed
10033 CALL RANDOM_SEED(size = n)
10036 CALL SYSTEM_CLOCK(COUNT=clock)
10038 seed = clock + 37 * (/ (i - 1, i = 1, n) /)
10039 CALL RANDOM_SEED(PUT = seed)
10045 @item @emph{See also}:
10046 @ref{RANDOM_NUMBER}
10052 @section @code{RANGE} --- Decimal exponent range
10054 @cindex model representation, range
10057 @item @emph{Description}:
10058 @code{RANGE(X)} returns the decimal exponent range in the model of the
10061 @item @emph{Standard}:
10062 Fortran 95 and later
10064 @item @emph{Class}:
10067 @item @emph{Syntax}:
10068 @code{RESULT = RANGE(X)}
10070 @item @emph{Arguments}:
10071 @multitable @columnfractions .15 .70
10072 @item @var{X} @tab Shall be of type @code{INTEGER}, @code{REAL}
10076 @item @emph{Return value}:
10077 The return value is of type @code{INTEGER} and of the default integer
10080 @item @emph{See also}:
10081 @ref{SELECTED_REAL_KIND}, @ref{PRECISION}
10083 @item @emph{Example}:
10084 See @code{PRECISION} for an example.
10090 @section @code{REAL} --- Convert to real type
10096 @cindex conversion, to real
10097 @cindex complex numbers, real part
10100 @item @emph{Description}:
10101 @code{REAL(A [, KIND])} converts its argument @var{A} to a real type. The
10102 @code{REALPART} function is provided for compatibility with @command{g77},
10103 and its use is strongly discouraged.
10105 @item @emph{Standard}:
10106 Fortran 77 and later
10108 @item @emph{Class}:
10111 @item @emph{Syntax}:
10112 @multitable @columnfractions .80
10113 @item @code{RESULT = REAL(A [, KIND])}
10114 @item @code{RESULT = REALPART(Z)}
10117 @item @emph{Arguments}:
10118 @multitable @columnfractions .15 .70
10119 @item @var{A} @tab Shall be @code{INTEGER}, @code{REAL}, or
10121 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
10122 expression indicating the kind parameter of the result.
10125 @item @emph{Return value}:
10126 These functions return a @code{REAL} variable or array under
10127 the following rules:
10131 @code{REAL(A)} is converted to a default real type if @var{A} is an
10132 integer or real variable.
10134 @code{REAL(A)} is converted to a real type with the kind type parameter
10135 of @var{A} if @var{A} is a complex variable.
10137 @code{REAL(A, KIND)} is converted to a real type with kind type
10138 parameter @var{KIND} if @var{A} is a complex, integer, or real
10142 @item @emph{Example}:
10145 complex :: x = (1.0, 2.0)
10146 print *, real(x), real(x,8), realpart(x)
10147 end program test_real
10150 @item @emph{Specific names}:
10151 @multitable @columnfractions .20 .20 .20 .25
10152 @item Name @tab Argument @tab Return type @tab Standard
10153 @item @code{FLOAT(A)} @tab @code{INTEGER(4)} @tab @code{REAL(4)} @tab Fortran 77 and later
10154 @item @code{DFLOAT(A)} @tab @code{INTEGER(4)} @tab @code{REAL(8)} @tab GNU extension
10155 @item @code{SNGL(A)} @tab @code{INTEGER(8)} @tab @code{REAL(4)} @tab Fortran 77 and later
10159 @item @emph{See also}:
10167 @section @code{RENAME} --- Rename a file
10169 @cindex file system, rename file
10172 @item @emph{Description}:
10173 Renames a file from file @var{PATH1} to @var{PATH2}. A null
10174 character (@code{CHAR(0)}) can be used to mark the end of the names in
10175 @var{PATH1} and @var{PATH2}; otherwise, trailing blanks in the file
10176 names are ignored. If the @var{STATUS} argument is supplied, it
10177 contains 0 on success or a nonzero error code upon return; see
10180 This intrinsic is provided in both subroutine and function forms;
10181 however, only one form can be used in any given program unit.
10183 @item @emph{Standard}:
10186 @item @emph{Class}:
10187 Subroutine, function
10189 @item @emph{Syntax}:
10190 @multitable @columnfractions .80
10191 @item @code{CALL RENAME(PATH1, PATH2 [, STATUS])}
10192 @item @code{STATUS = RENAME(PATH1, PATH2)}
10195 @item @emph{Arguments}:
10196 @multitable @columnfractions .15 .70
10197 @item @var{PATH1} @tab Shall be of default @code{CHARACTER} type.
10198 @item @var{PATH2} @tab Shall be of default @code{CHARACTER} type.
10199 @item @var{STATUS} @tab (Optional) Shall be of default @code{INTEGER} type.
10202 @item @emph{See also}:
10210 @section @code{REPEAT} --- Repeated string concatenation
10212 @cindex string, repeat
10213 @cindex string, concatenate
10216 @item @emph{Description}:
10217 Concatenates @var{NCOPIES} copies of a string.
10219 @item @emph{Standard}:
10220 Fortran 95 and later
10222 @item @emph{Class}:
10223 Transformational function
10225 @item @emph{Syntax}:
10226 @code{RESULT = REPEAT(STRING, NCOPIES)}
10228 @item @emph{Arguments}:
10229 @multitable @columnfractions .15 .70
10230 @item @var{STRING} @tab Shall be scalar and of type @code{CHARACTER}.
10231 @item @var{NCOPIES} @tab Shall be scalar and of type @code{INTEGER}.
10234 @item @emph{Return value}:
10235 A new scalar of type @code{CHARACTER} built up from @var{NCOPIES} copies
10238 @item @emph{Example}:
10240 program test_repeat
10241 write(*,*) repeat("x", 5) ! "xxxxx"
10249 @section @code{RESHAPE} --- Function to reshape an array
10251 @cindex array, change dimensions
10252 @cindex array, transmogrify
10255 @item @emph{Description}:
10256 Reshapes @var{SOURCE} to correspond to @var{SHAPE}. If necessary,
10257 the new array may be padded with elements from @var{PAD} or permuted
10258 as defined by @var{ORDER}.
10260 @item @emph{Standard}:
10261 Fortran 95 and later
10263 @item @emph{Class}:
10264 Transformational function
10266 @item @emph{Syntax}:
10267 @code{RESULT = RESHAPE(SOURCE, SHAPE[, PAD, ORDER])}
10269 @item @emph{Arguments}:
10270 @multitable @columnfractions .15 .70
10271 @item @var{SOURCE} @tab Shall be an array of any type.
10272 @item @var{SHAPE} @tab Shall be of type @code{INTEGER} and an
10273 array of rank one. Its values must be positive or zero.
10274 @item @var{PAD} @tab (Optional) shall be an array of the same
10275 type as @var{SOURCE}.
10276 @item @var{ORDER} @tab (Optional) shall be of type @code{INTEGER}
10277 and an array of the same shape as @var{SHAPE}. Its values shall
10278 be a permutation of the numbers from 1 to n, where n is the size of
10279 @var{SHAPE}. If @var{ORDER} is absent, the natural ordering shall
10283 @item @emph{Return value}:
10284 The result is an array of shape @var{SHAPE} with the same type as
10287 @item @emph{Example}:
10289 PROGRAM test_reshape
10290 INTEGER, DIMENSION(4) :: x
10291 WRITE(*,*) SHAPE(x) ! prints "4"
10292 WRITE(*,*) SHAPE(RESHAPE(x, (/2, 2/))) ! prints "2 2"
10296 @item @emph{See also}:
10303 @section @code{RRSPACING} --- Reciprocal of the relative spacing
10305 @cindex real number, relative spacing
10306 @cindex floating point, relative spacing
10310 @item @emph{Description}:
10311 @code{RRSPACING(X)} returns the reciprocal of the relative spacing of
10312 model numbers near @var{X}.
10314 @item @emph{Standard}:
10315 Fortran 95 and later
10317 @item @emph{Class}:
10320 @item @emph{Syntax}:
10321 @code{RESULT = RRSPACING(X)}
10323 @item @emph{Arguments}:
10324 @multitable @columnfractions .15 .70
10325 @item @var{X} @tab Shall be of type @code{REAL}.
10328 @item @emph{Return value}:
10329 The return value is of the same type and kind as @var{X}.
10330 The value returned is equal to
10331 @code{ABS(FRACTION(X)) * FLOAT(RADIX(X))**DIGITS(X)}.
10333 @item @emph{See also}:
10340 @section @code{RSHIFT} --- Right shift bits
10342 @cindex bits, shift right
10345 @item @emph{Description}:
10346 @code{RSHIFT} returns a value corresponding to @var{I} with all of the
10347 bits shifted right by @var{SHIFT} places. If the absolute value of
10348 @var{SHIFT} is greater than @code{BIT_SIZE(I)}, the value is undefined.
10349 Bits shifted out from the right end are lost. The fill is arithmetic: the
10350 bits shifted in from the left end are equal to the leftmost bit, which in
10351 two's complement representation is the sign bit.
10353 This function has been superseded by the @code{SHIFTA} intrinsic, which
10354 is standard in Fortran 2008 and later.
10356 @item @emph{Standard}:
10359 @item @emph{Class}:
10362 @item @emph{Syntax}:
10363 @code{RESULT = RSHIFT(I, SHIFT)}
10365 @item @emph{Arguments}:
10366 @multitable @columnfractions .15 .70
10367 @item @var{I} @tab The type shall be @code{INTEGER}.
10368 @item @var{SHIFT} @tab The type shall be @code{INTEGER}.
10371 @item @emph{Return value}:
10372 The return value is of type @code{INTEGER} and of the same kind as
10375 @item @emph{See also}:
10376 @ref{ISHFT}, @ref{ISHFTC}, @ref{LSHIFT}, @ref{SHIFTA}, @ref{SHIFTR},
10384 @section @code{SAME_TYPE_AS} --- Query dynamic types for equality
10385 @fnindex SAME_TYPE_AS
10388 @item @emph{Description}:
10389 Query dynamic types for equality.
10391 @item @emph{Standard}:
10392 Fortran 2003 and later
10394 @item @emph{Class}:
10397 @item @emph{Syntax}:
10398 @code{RESULT = SAME_TYPE_AS(A, B)}
10400 @item @emph{Arguments}:
10401 @multitable @columnfractions .15 .70
10402 @item @var{A} @tab Shall be an object of extensible declared type or
10403 unlimited polymorphic.
10404 @item @var{B} @tab Shall be an object of extensible declared type or
10405 unlimited polymorphic.
10408 @item @emph{Return value}:
10409 The return value is a scalar of type default logical. It is true if and
10410 only if the dynamic type of A is the same as the dynamic type of B.
10412 @item @emph{See also}:
10413 @ref{EXTENDS_TYPE_OF}
10420 @section @code{SCALE} --- Scale a real value
10422 @cindex real number, scale
10423 @cindex floating point, scale
10426 @item @emph{Description}:
10427 @code{SCALE(X,I)} returns @code{X * RADIX(X)**I}.
10429 @item @emph{Standard}:
10430 Fortran 95 and later
10432 @item @emph{Class}:
10435 @item @emph{Syntax}:
10436 @code{RESULT = SCALE(X, I)}
10438 @item @emph{Arguments}:
10439 @multitable @columnfractions .15 .70
10440 @item @var{X} @tab The type of the argument shall be a @code{REAL}.
10441 @item @var{I} @tab The type of the argument shall be a @code{INTEGER}.
10444 @item @emph{Return value}:
10445 The return value is of the same type and kind as @var{X}.
10446 Its value is @code{X * RADIX(X)**I}.
10448 @item @emph{Example}:
10451 real :: x = 178.1387e-4
10453 print *, scale(x,i), x*radix(x)**i
10454 end program test_scale
10462 @section @code{SCAN} --- Scan a string for the presence of a set of characters
10464 @cindex string, find subset
10467 @item @emph{Description}:
10468 Scans a @var{STRING} for any of the characters in a @var{SET}
10471 If @var{BACK} is either absent or equals @code{FALSE}, this function
10472 returns the position of the leftmost character of @var{STRING} that is
10473 in @var{SET}. If @var{BACK} equals @code{TRUE}, the rightmost position
10474 is returned. If no character of @var{SET} is found in @var{STRING}, the
10477 @item @emph{Standard}:
10478 Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
10480 @item @emph{Class}:
10483 @item @emph{Syntax}:
10484 @code{RESULT = SCAN(STRING, SET[, BACK [, KIND]])}
10486 @item @emph{Arguments}:
10487 @multitable @columnfractions .15 .70
10488 @item @var{STRING} @tab Shall be of type @code{CHARACTER}.
10489 @item @var{SET} @tab Shall be of type @code{CHARACTER}.
10490 @item @var{BACK} @tab (Optional) shall be of type @code{LOGICAL}.
10491 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
10492 expression indicating the kind parameter of the result.
10495 @item @emph{Return value}:
10496 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
10497 @var{KIND} is absent, the return value is of default integer kind.
10499 @item @emph{Example}:
10502 WRITE(*,*) SCAN("FORTRAN", "AO") ! 2, found 'O'
10503 WRITE(*,*) SCAN("FORTRAN", "AO", .TRUE.) ! 6, found 'A'
10504 WRITE(*,*) SCAN("FORTRAN", "C++") ! 0, found none
10508 @item @emph{See also}:
10509 @ref{INDEX intrinsic}, @ref{VERIFY}
10515 @section @code{SECNDS} --- Time function
10517 @cindex time, elapsed
10518 @cindex elapsed time
10521 @item @emph{Description}:
10522 @code{SECNDS(X)} gets the time in seconds from the real-time system clock.
10523 @var{X} is a reference time, also in seconds. If this is zero, the time in
10524 seconds from midnight is returned. This function is non-standard and its
10525 use is discouraged.
10527 @item @emph{Standard}:
10530 @item @emph{Class}:
10533 @item @emph{Syntax}:
10534 @code{RESULT = SECNDS (X)}
10536 @item @emph{Arguments}:
10537 @multitable @columnfractions .15 .70
10538 @item @var{T} @tab Shall be of type @code{REAL(4)}.
10539 @item @var{X} @tab Shall be of type @code{REAL(4)}.
10542 @item @emph{Return value}:
10545 @item @emph{Example}:
10547 program test_secnds
10550 print *, secnds (0.0) ! seconds since midnight
10551 t1 = secnds (0.0) ! reference time
10552 do i = 1, 10000000 ! do something
10554 t2 = secnds (t1) ! elapsed time
10555 print *, "Something took ", t2, " seconds."
10556 end program test_secnds
10563 @section @code{SECOND} --- CPU time function
10565 @cindex time, elapsed
10566 @cindex elapsed time
10569 @item @emph{Description}:
10570 Returns a @code{REAL(4)} value representing the elapsed CPU time in
10571 seconds. This provides the same functionality as the standard
10572 @code{CPU_TIME} intrinsic, and is only included for backwards
10575 This intrinsic is provided in both subroutine and function forms;
10576 however, only one form can be used in any given program unit.
10578 @item @emph{Standard}:
10581 @item @emph{Class}:
10582 Subroutine, function
10584 @item @emph{Syntax}:
10585 @multitable @columnfractions .80
10586 @item @code{CALL SECOND(TIME)}
10587 @item @code{TIME = SECOND()}
10590 @item @emph{Arguments}:
10591 @multitable @columnfractions .15 .70
10592 @item @var{TIME} @tab Shall be of type @code{REAL(4)}.
10595 @item @emph{Return value}:
10596 In either syntax, @var{TIME} is set to the process's current runtime in
10599 @item @emph{See also}:
10606 @node SELECTED_CHAR_KIND
10607 @section @code{SELECTED_CHAR_KIND} --- Choose character kind
10608 @fnindex SELECTED_CHAR_KIND
10609 @cindex character kind
10610 @cindex kind, character
10613 @item @emph{Description}:
10615 @code{SELECTED_CHAR_KIND(NAME)} returns the kind value for the character
10616 set named @var{NAME}, if a character set with such a name is supported,
10617 or @math{-1} otherwise. Currently, supported character sets include
10618 ``ASCII'' and ``DEFAULT'', which are equivalent, and ``ISO_10646''
10619 (Universal Character Set, UCS-4) which is commonly known as Unicode.
10621 @item @emph{Standard}:
10622 Fortran 2003 and later
10624 @item @emph{Class}:
10625 Transformational function
10627 @item @emph{Syntax}:
10628 @code{RESULT = SELECTED_CHAR_KIND(NAME)}
10630 @item @emph{Arguments}:
10631 @multitable @columnfractions .15 .70
10632 @item @var{NAME} @tab Shall be a scalar and of the default character type.
10635 @item @emph{Example}:
10637 program character_kind
10638 use iso_fortran_env
10640 integer, parameter :: ascii = selected_char_kind ("ascii")
10641 integer, parameter :: ucs4 = selected_char_kind ('ISO_10646')
10643 character(kind=ascii, len=26) :: alphabet
10644 character(kind=ucs4, len=30) :: hello_world
10646 alphabet = ascii_"abcdefghijklmnopqrstuvwxyz"
10647 hello_world = ucs4_'Hello World and Ni Hao -- ' &
10648 // char (int (z'4F60'), ucs4) &
10649 // char (int (z'597D'), ucs4)
10651 write (*,*) alphabet
10653 open (output_unit, encoding='UTF-8')
10654 write (*,*) trim (hello_world)
10655 end program character_kind
10661 @node SELECTED_INT_KIND
10662 @section @code{SELECTED_INT_KIND} --- Choose integer kind
10663 @fnindex SELECTED_INT_KIND
10664 @cindex integer kind
10665 @cindex kind, integer
10668 @item @emph{Description}:
10669 @code{SELECTED_INT_KIND(R)} return the kind value of the smallest integer
10670 type that can represent all values ranging from @math{-10^R} (exclusive)
10671 to @math{10^R} (exclusive). If there is no integer kind that accommodates
10672 this range, @code{SELECTED_INT_KIND} returns @math{-1}.
10674 @item @emph{Standard}:
10675 Fortran 95 and later
10677 @item @emph{Class}:
10678 Transformational function
10680 @item @emph{Syntax}:
10681 @code{RESULT = SELECTED_INT_KIND(R)}
10683 @item @emph{Arguments}:
10684 @multitable @columnfractions .15 .70
10685 @item @var{R} @tab Shall be a scalar and of type @code{INTEGER}.
10688 @item @emph{Example}:
10690 program large_integers
10691 integer,parameter :: k5 = selected_int_kind(5)
10692 integer,parameter :: k15 = selected_int_kind(15)
10693 integer(kind=k5) :: i5
10694 integer(kind=k15) :: i15
10696 print *, huge(i5), huge(i15)
10698 ! The following inequalities are always true
10699 print *, huge(i5) >= 10_k5**5-1
10700 print *, huge(i15) >= 10_k15**15-1
10701 end program large_integers
10707 @node SELECTED_REAL_KIND
10708 @section @code{SELECTED_REAL_KIND} --- Choose real kind
10709 @fnindex SELECTED_REAL_KIND
10712 @cindex radix, real
10715 @item @emph{Description}:
10716 @code{SELECTED_REAL_KIND(P,R)} returns the kind value of a real data type
10717 with decimal precision of at least @code{P} digits, exponent range of
10718 at least @code{R}, and with a radix of @code{RADIX}.
10720 @item @emph{Standard}:
10721 Fortran 95 and later, with @code{RADIX} Fortran 2008 or later
10723 @item @emph{Class}:
10724 Transformational function
10726 @item @emph{Syntax}:
10727 @code{RESULT = SELECTED_REAL_KIND([P, R, RADIX])}
10729 @item @emph{Arguments}:
10730 @multitable @columnfractions .15 .70
10731 @item @var{P} @tab (Optional) shall be a scalar and of type @code{INTEGER}.
10732 @item @var{R} @tab (Optional) shall be a scalar and of type @code{INTEGER}.
10733 @item @var{RADIX} @tab (Optional) shall be a scalar and of type @code{INTEGER}.
10735 Before Fortran 2008, at least one of the arguments @var{R} or @var{P} shall
10736 be present; since Fortran 2008, they are assumed to be zero if absent.
10738 @item @emph{Return value}:
10740 @code{SELECTED_REAL_KIND} returns the value of the kind type parameter of
10741 a real data type with decimal precision of at least @code{P} digits, a
10742 decimal exponent range of at least @code{R}, and with the requested
10743 @code{RADIX}. If the @code{RADIX} parameter is absent, real kinds with
10744 any radix can be returned. If more than one real data type meet the
10745 criteria, the kind of the data type with the smallest decimal precision
10746 is returned. If no real data type matches the criteria, the result is
10748 @item -1 if the processor does not support a real data type with a
10749 precision greater than or equal to @code{P}, but the @code{R} and
10750 @code{RADIX} requirements can be fulfilled
10751 @item -2 if the processor does not support a real type with an exponent
10752 range greater than or equal to @code{R}, but @code{P} and @code{RADIX}
10754 @item -3 if @code{RADIX} but not @code{P} and @code{R} requirements
10756 @item -4 if @code{RADIX} and either @code{P} or @code{R} requirements
10758 @item -5 if there is no real type with the given @code{RADIX}
10761 @item @emph{See also}:
10762 @ref{PRECISION}, @ref{RANGE}, @ref{RADIX}
10764 @item @emph{Example}:
10767 integer,parameter :: p6 = selected_real_kind(6)
10768 integer,parameter :: p10r100 = selected_real_kind(10,100)
10769 integer,parameter :: r400 = selected_real_kind(r=400)
10771 real(kind=p10r100) :: y
10772 real(kind=r400) :: z
10774 print *, precision(x), range(x)
10775 print *, precision(y), range(y)
10776 print *, precision(z), range(z)
10777 end program real_kinds
10784 @section @code{SET_EXPONENT} --- Set the exponent of the model
10785 @fnindex SET_EXPONENT
10786 @cindex real number, set exponent
10787 @cindex floating point, set exponent
10790 @item @emph{Description}:
10791 @code{SET_EXPONENT(X, I)} returns the real number whose fractional part
10792 is that that of @var{X} and whose exponent part is @var{I}.
10794 @item @emph{Standard}:
10795 Fortran 95 and later
10797 @item @emph{Class}:
10800 @item @emph{Syntax}:
10801 @code{RESULT = SET_EXPONENT(X, I)}
10803 @item @emph{Arguments}:
10804 @multitable @columnfractions .15 .70
10805 @item @var{X} @tab Shall be of type @code{REAL}.
10806 @item @var{I} @tab Shall be of type @code{INTEGER}.
10809 @item @emph{Return value}:
10810 The return value is of the same type and kind as @var{X}.
10811 The real number whose fractional part
10812 is that that of @var{X} and whose exponent part if @var{I} is returned;
10813 it is @code{FRACTION(X) * RADIX(X)**I}.
10815 @item @emph{Example}:
10817 PROGRAM test_setexp
10818 REAL :: x = 178.1387e-4
10820 PRINT *, SET_EXPONENT(x, i), FRACTION(x) * RADIX(x)**i
10829 @section @code{SHAPE} --- Determine the shape of an array
10831 @cindex array, shape
10834 @item @emph{Description}:
10835 Determines the shape of an array.
10837 @item @emph{Standard}:
10838 Fortran 95 and later
10840 @item @emph{Class}:
10843 @item @emph{Syntax}:
10844 @code{RESULT = SHAPE(SOURCE)}
10846 @item @emph{Arguments}:
10847 @multitable @columnfractions .15 .70
10848 @item @var{SOURCE} @tab Shall be an array or scalar of any type.
10849 If @var{SOURCE} is a pointer it must be associated and allocatable
10850 arrays must be allocated.
10853 @item @emph{Return value}:
10854 An @code{INTEGER} array of rank one with as many elements as @var{SOURCE}
10855 has dimensions. The elements of the resulting array correspond to the extend
10856 of @var{SOURCE} along the respective dimensions. If @var{SOURCE} is a scalar,
10857 the result is the rank one array of size zero.
10859 @item @emph{Example}:
10862 INTEGER, DIMENSION(-1:1, -1:2) :: A
10863 WRITE(*,*) SHAPE(A) ! (/ 3, 4 /)
10864 WRITE(*,*) SIZE(SHAPE(42)) ! (/ /)
10868 @item @emph{See also}:
10869 @ref{RESHAPE}, @ref{SIZE}
10875 @section @code{SHIFTA} --- Right shift with fill
10877 @cindex bits, shift right
10878 @cindex shift, right with fill
10881 @item @emph{Description}:
10882 @code{SHIFTA} returns a value corresponding to @var{I} with all of the
10883 bits shifted right by @var{SHIFT} places. If the absolute value of
10884 @var{SHIFT} is greater than @code{BIT_SIZE(I)}, the value is undefined.
10885 Bits shifted out from the right end are lost. The fill is arithmetic: the
10886 bits shifted in from the left end are equal to the leftmost bit, which in
10887 two's complement representation is the sign bit.
10889 @item @emph{Standard}:
10890 Fortran 2008 and later
10892 @item @emph{Class}:
10895 @item @emph{Syntax}:
10896 @code{RESULT = SHIFTA(I, SHIFT)}
10898 @item @emph{Arguments}:
10899 @multitable @columnfractions .15 .70
10900 @item @var{I} @tab The type shall be @code{INTEGER}.
10901 @item @var{SHIFT} @tab The type shall be @code{INTEGER}.
10904 @item @emph{Return value}:
10905 The return value is of type @code{INTEGER} and of the same kind as
10908 @item @emph{See also}:
10909 @ref{SHIFTL}, @ref{SHIFTR}
10915 @section @code{SHIFTL} --- Left shift
10917 @cindex bits, shift left
10918 @cindex shift, left
10921 @item @emph{Description}:
10922 @code{SHIFTL} returns a value corresponding to @var{I} with all of the
10923 bits shifted left by @var{SHIFT} places. If the absolute value of
10924 @var{SHIFT} is greater than @code{BIT_SIZE(I)}, the value is undefined.
10925 Bits shifted out from the left end are lost, and bits shifted in from
10926 the right end are set to 0.
10928 @item @emph{Standard}:
10929 Fortran 2008 and later
10931 @item @emph{Class}:
10934 @item @emph{Syntax}:
10935 @code{RESULT = SHIFTL(I, SHIFT)}
10937 @item @emph{Arguments}:
10938 @multitable @columnfractions .15 .70
10939 @item @var{I} @tab The type shall be @code{INTEGER}.
10940 @item @var{SHIFT} @tab The type shall be @code{INTEGER}.
10943 @item @emph{Return value}:
10944 The return value is of type @code{INTEGER} and of the same kind as
10947 @item @emph{See also}:
10948 @ref{SHIFTA}, @ref{SHIFTR}
10954 @section @code{SHIFTR} --- Right shift
10956 @cindex bits, shift right
10957 @cindex shift, right
10960 @item @emph{Description}:
10961 @code{SHIFTR} returns a value corresponding to @var{I} with all of the
10962 bits shifted right by @var{SHIFT} places. If the absolute value of
10963 @var{SHIFT} is greater than @code{BIT_SIZE(I)}, the value is undefined.
10964 Bits shifted out from the right end are lost, and bits shifted in from
10965 the left end are set to 0.
10967 @item @emph{Standard}:
10968 Fortran 2008 and later
10970 @item @emph{Class}:
10973 @item @emph{Syntax}:
10974 @code{RESULT = SHIFTR(I, SHIFT)}
10976 @item @emph{Arguments}:
10977 @multitable @columnfractions .15 .70
10978 @item @var{I} @tab The type shall be @code{INTEGER}.
10979 @item @var{SHIFT} @tab The type shall be @code{INTEGER}.
10982 @item @emph{Return value}:
10983 The return value is of type @code{INTEGER} and of the same kind as
10986 @item @emph{See also}:
10987 @ref{SHIFTA}, @ref{SHIFTL}
10993 @section @code{SIGN} --- Sign copying function
10997 @cindex sign copying
11000 @item @emph{Description}:
11001 @code{SIGN(A,B)} returns the value of @var{A} with the sign of @var{B}.
11003 @item @emph{Standard}:
11004 Fortran 77 and later
11006 @item @emph{Class}:
11009 @item @emph{Syntax}:
11010 @code{RESULT = SIGN(A, B)}
11012 @item @emph{Arguments}:
11013 @multitable @columnfractions .15 .70
11014 @item @var{A} @tab Shall be of type @code{INTEGER} or @code{REAL}
11015 @item @var{B} @tab Shall be of the same type and kind as @var{A}
11018 @item @emph{Return value}:
11019 The kind of the return value is that of @var{A} and @var{B}.
11020 If @math{B\ge 0} then the result is @code{ABS(A)}, else
11021 it is @code{-ABS(A)}.
11023 @item @emph{Example}:
11026 print *, sign(-12,1)
11027 print *, sign(-12,0)
11028 print *, sign(-12,-1)
11030 print *, sign(-12.,1.)
11031 print *, sign(-12.,0.)
11032 print *, sign(-12.,-1.)
11033 end program test_sign
11036 @item @emph{Specific names}:
11037 @multitable @columnfractions .20 .20 .20 .25
11038 @item Name @tab Arguments @tab Return type @tab Standard
11039 @item @code{SIGN(A,B)} @tab @code{REAL(4) A, B} @tab @code{REAL(4)} @tab f77, gnu
11040 @item @code{ISIGN(A,B)} @tab @code{INTEGER(4) A, B} @tab @code{INTEGER(4)} @tab f77, gnu
11041 @item @code{DSIGN(A,B)} @tab @code{REAL(8) A, B} @tab @code{REAL(8)} @tab f77, gnu
11048 @section @code{SIGNAL} --- Signal handling subroutine (or function)
11050 @cindex system, signal handling
11053 @item @emph{Description}:
11054 @code{SIGNAL(NUMBER, HANDLER [, STATUS])} causes external subroutine
11055 @var{HANDLER} to be executed with a single integer argument when signal
11056 @var{NUMBER} occurs. If @var{HANDLER} is an integer, it can be used to
11057 turn off handling of signal @var{NUMBER} or revert to its default
11058 action. See @code{signal(2)}.
11060 If @code{SIGNAL} is called as a subroutine and the @var{STATUS} argument
11061 is supplied, it is set to the value returned by @code{signal(2)}.
11063 @item @emph{Standard}:
11066 @item @emph{Class}:
11067 Subroutine, function
11069 @item @emph{Syntax}:
11070 @multitable @columnfractions .80
11071 @item @code{CALL SIGNAL(NUMBER, HANDLER [, STATUS])}
11072 @item @code{STATUS = SIGNAL(NUMBER, HANDLER)}
11075 @item @emph{Arguments}:
11076 @multitable @columnfractions .15 .70
11077 @item @var{NUMBER} @tab Shall be a scalar integer, with @code{INTENT(IN)}
11078 @item @var{HANDLER}@tab Signal handler (@code{INTEGER FUNCTION} or
11079 @code{SUBROUTINE}) or dummy/global @code{INTEGER} scalar.
11080 @code{INTEGER}. It is @code{INTENT(IN)}.
11081 @item @var{STATUS} @tab (Optional) @var{STATUS} shall be a scalar
11082 integer. It has @code{INTENT(OUT)}.
11084 @c TODO: What should the interface of the handler be? Does it take arguments?
11086 @item @emph{Return value}:
11087 The @code{SIGNAL} function returns the value returned by @code{signal(2)}.
11089 @item @emph{Example}:
11091 program test_signal
11093 external handler_print
11095 call signal (12, handler_print)
11096 call signal (10, 1)
11099 end program test_signal
11106 @section @code{SIN} --- Sine function
11112 @cindex trigonometric function, sine
11116 @item @emph{Description}:
11117 @code{SIN(X)} computes the sine of @var{X}.
11119 @item @emph{Standard}:
11120 Fortran 77 and later
11122 @item @emph{Class}:
11125 @item @emph{Syntax}:
11126 @code{RESULT = SIN(X)}
11128 @item @emph{Arguments}:
11129 @multitable @columnfractions .15 .70
11130 @item @var{X} @tab The type shall be @code{REAL} or
11134 @item @emph{Return value}:
11135 The return value has same type and kind as @var{X}.
11137 @item @emph{Example}:
11142 end program test_sin
11145 @item @emph{Specific names}:
11146 @multitable @columnfractions .20 .20 .20 .25
11147 @item Name @tab Argument @tab Return type @tab Standard
11148 @item @code{SIN(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab f77, gnu
11149 @item @code{DSIN(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab f95, gnu
11150 @item @code{CSIN(X)} @tab @code{COMPLEX(4) X} @tab @code{COMPLEX(4)} @tab f95, gnu
11151 @item @code{ZSIN(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab f95, gnu
11152 @item @code{CDSIN(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab f95, gnu
11155 @item @emph{See also}:
11162 @section @code{SINH} --- Hyperbolic sine function
11165 @cindex hyperbolic sine
11166 @cindex hyperbolic function, sine
11167 @cindex sine, hyperbolic
11170 @item @emph{Description}:
11171 @code{SINH(X)} computes the hyperbolic sine of @var{X}.
11173 @item @emph{Standard}:
11174 Fortran 95 and later, for a complex argument Fortran 2008 or later
11176 @item @emph{Class}:
11179 @item @emph{Syntax}:
11180 @code{RESULT = SINH(X)}
11182 @item @emph{Arguments}:
11183 @multitable @columnfractions .15 .70
11184 @item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
11187 @item @emph{Return value}:
11188 The return value has same type and kind as @var{X}.
11190 @item @emph{Example}:
11193 real(8) :: x = - 1.0_8
11195 end program test_sinh
11198 @item @emph{Specific names}:
11199 @multitable @columnfractions .20 .20 .20 .25
11200 @item Name @tab Argument @tab Return type @tab Standard
11201 @item @code{SINH(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 95 and later
11202 @item @code{DSINH(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 95 and later
11205 @item @emph{See also}:
11212 @section @code{SIZE} --- Determine the size of an array
11214 @cindex array, size
11215 @cindex array, number of elements
11216 @cindex array, count elements
11219 @item @emph{Description}:
11220 Determine the extent of @var{ARRAY} along a specified dimension @var{DIM},
11221 or the total number of elements in @var{ARRAY} if @var{DIM} is absent.
11223 @item @emph{Standard}:
11224 Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
11226 @item @emph{Class}:
11229 @item @emph{Syntax}:
11230 @code{RESULT = SIZE(ARRAY[, DIM [, KIND]])}
11232 @item @emph{Arguments}:
11233 @multitable @columnfractions .15 .70
11234 @item @var{ARRAY} @tab Shall be an array of any type. If @var{ARRAY} is
11235 a pointer it must be associated and allocatable arrays must be allocated.
11236 @item @var{DIM} @tab (Optional) shall be a scalar of type @code{INTEGER}
11237 and its value shall be in the range from 1 to n, where n equals the rank
11239 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
11240 expression indicating the kind parameter of the result.
11243 @item @emph{Return value}:
11244 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
11245 @var{KIND} is absent, the return value is of default integer kind.
11247 @item @emph{Example}:
11250 WRITE(*,*) SIZE((/ 1, 2 /)) ! 2
11254 @item @emph{See also}:
11255 @ref{SHAPE}, @ref{RESHAPE}
11260 @section @code{SIZEOF} --- Size in bytes of an expression
11262 @cindex expression size
11263 @cindex size of an expression
11266 @item @emph{Description}:
11267 @code{SIZEOF(X)} calculates the number of bytes of storage the
11268 expression @code{X} occupies.
11270 @item @emph{Standard}:
11273 @item @emph{Class}:
11276 @item @emph{Syntax}:
11277 @code{N = SIZEOF(X)}
11279 @item @emph{Arguments}:
11280 @multitable @columnfractions .15 .70
11281 @item @var{X} @tab The argument shall be of any type, rank or shape.
11284 @item @emph{Return value}:
11285 The return value is of type integer and of the system-dependent kind
11286 @var{C_SIZE_T} (from the @var{ISO_C_BINDING} module). Its value is the
11287 number of bytes occupied by the argument. If the argument has the
11288 @code{POINTER} attribute, the number of bytes of the storage area pointed
11289 to is returned. If the argument is of a derived type with @code{POINTER}
11290 or @code{ALLOCATABLE} components, the return value doesn't account for
11291 the sizes of the data pointed to by these components. If the argument is
11292 polymorphic, the size according to the declared type is returned.
11294 @item @emph{Example}:
11298 print *, (sizeof(s)/sizeof(r) == 5)
11301 The example will print @code{.TRUE.} unless you are using a platform
11302 where default @code{REAL} variables are unusually padded.
11304 @item @emph{See also}:
11305 @ref{C_SIZEOF}, @ref{STORAGE_SIZE}
11310 @section @code{SLEEP} --- Sleep for the specified number of seconds
11312 @cindex delayed execution
11315 @item @emph{Description}:
11316 Calling this subroutine causes the process to pause for @var{SECONDS} seconds.
11318 @item @emph{Standard}:
11321 @item @emph{Class}:
11324 @item @emph{Syntax}:
11325 @code{CALL SLEEP(SECONDS)}
11327 @item @emph{Arguments}:
11328 @multitable @columnfractions .15 .70
11329 @item @var{SECONDS} @tab The type shall be of default @code{INTEGER}.
11332 @item @emph{Example}:
11343 @section @code{SPACING} --- Smallest distance between two numbers of a given type
11345 @cindex real number, relative spacing
11346 @cindex floating point, relative spacing
11349 @item @emph{Description}:
11350 Determines the distance between the argument @var{X} and the nearest
11351 adjacent number of the same type.
11353 @item @emph{Standard}:
11354 Fortran 95 and later
11356 @item @emph{Class}:
11359 @item @emph{Syntax}:
11360 @code{RESULT = SPACING(X)}
11362 @item @emph{Arguments}:
11363 @multitable @columnfractions .15 .70
11364 @item @var{X} @tab Shall be of type @code{REAL}.
11367 @item @emph{Return value}:
11368 The result is of the same type as the input argument @var{X}.
11370 @item @emph{Example}:
11372 PROGRAM test_spacing
11373 INTEGER, PARAMETER :: SGL = SELECTED_REAL_KIND(p=6, r=37)
11374 INTEGER, PARAMETER :: DBL = SELECTED_REAL_KIND(p=13, r=200)
11376 WRITE(*,*) spacing(1.0_SGL) ! "1.1920929E-07" on i686
11377 WRITE(*,*) spacing(1.0_DBL) ! "2.220446049250313E-016" on i686
11381 @item @emph{See also}:
11388 @section @code{SPREAD} --- Add a dimension to an array
11390 @cindex array, increase dimension
11391 @cindex array, duplicate elements
11392 @cindex array, duplicate dimensions
11395 @item @emph{Description}:
11396 Replicates a @var{SOURCE} array @var{NCOPIES} times along a specified
11397 dimension @var{DIM}.
11399 @item @emph{Standard}:
11400 Fortran 95 and later
11402 @item @emph{Class}:
11403 Transformational function
11405 @item @emph{Syntax}:
11406 @code{RESULT = SPREAD(SOURCE, DIM, NCOPIES)}
11408 @item @emph{Arguments}:
11409 @multitable @columnfractions .15 .70
11410 @item @var{SOURCE} @tab Shall be a scalar or an array of any type and
11411 a rank less than seven.
11412 @item @var{DIM} @tab Shall be a scalar of type @code{INTEGER} with a
11413 value in the range from 1 to n+1, where n equals the rank of @var{SOURCE}.
11414 @item @var{NCOPIES} @tab Shall be a scalar of type @code{INTEGER}.
11417 @item @emph{Return value}:
11418 The result is an array of the same type as @var{SOURCE} and has rank n+1
11419 where n equals the rank of @var{SOURCE}.
11421 @item @emph{Example}:
11423 PROGRAM test_spread
11424 INTEGER :: a = 1, b(2) = (/ 1, 2 /)
11425 WRITE(*,*) SPREAD(A, 1, 2) ! "1 1"
11426 WRITE(*,*) SPREAD(B, 1, 2) ! "1 1 2 2"
11430 @item @emph{See also}:
11437 @section @code{SQRT} --- Square-root function
11444 @cindex square-root
11447 @item @emph{Description}:
11448 @code{SQRT(X)} computes the square root of @var{X}.
11450 @item @emph{Standard}:
11451 Fortran 77 and later
11453 @item @emph{Class}:
11456 @item @emph{Syntax}:
11457 @code{RESULT = SQRT(X)}
11459 @item @emph{Arguments}:
11460 @multitable @columnfractions .15 .70
11461 @item @var{X} @tab The type shall be @code{REAL} or
11465 @item @emph{Return value}:
11466 The return value is of type @code{REAL} or @code{COMPLEX}.
11467 The kind type parameter is the same as @var{X}.
11469 @item @emph{Example}:
11472 real(8) :: x = 2.0_8
11473 complex :: z = (1.0, 2.0)
11476 end program test_sqrt
11479 @item @emph{Specific names}:
11480 @multitable @columnfractions .20 .20 .20 .25
11481 @item Name @tab Argument @tab Return type @tab Standard
11482 @item @code{SQRT(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 95 and later
11483 @item @code{DSQRT(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 95 and later
11484 @item @code{CSQRT(X)} @tab @code{COMPLEX(4) X} @tab @code{COMPLEX(4)} @tab Fortran 95 and later
11485 @item @code{ZSQRT(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
11486 @item @code{CDSQRT(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
11493 @section @code{SRAND} --- Reinitialize the random number generator
11495 @cindex random number generation, seeding
11496 @cindex seeding a random number generator
11499 @item @emph{Description}:
11500 @code{SRAND} reinitializes the pseudo-random number generator
11501 called by @code{RAND} and @code{IRAND}. The new seed used by the
11502 generator is specified by the required argument @var{SEED}.
11504 @item @emph{Standard}:
11507 @item @emph{Class}:
11510 @item @emph{Syntax}:
11511 @code{CALL SRAND(SEED)}
11513 @item @emph{Arguments}:
11514 @multitable @columnfractions .15 .70
11515 @item @var{SEED} @tab Shall be a scalar @code{INTEGER(kind=4)}.
11518 @item @emph{Return value}:
11519 Does not return anything.
11521 @item @emph{Example}:
11522 See @code{RAND} and @code{IRAND} for examples.
11524 @item @emph{Notes}:
11525 The Fortran 2003 standard specifies the intrinsic @code{RANDOM_SEED} to
11526 initialize the pseudo-random numbers generator and @code{RANDOM_NUMBER}
11527 to generate pseudo-random numbers. Please note that in
11528 GNU Fortran, these two sets of intrinsics (@code{RAND},
11529 @code{IRAND} and @code{SRAND} on the one hand, @code{RANDOM_NUMBER} and
11530 @code{RANDOM_SEED} on the other hand) access two independent
11531 pseudo-random number generators.
11533 @item @emph{See also}:
11534 @ref{RAND}, @ref{RANDOM_SEED}, @ref{RANDOM_NUMBER}
11541 @section @code{STAT} --- Get file status
11543 @cindex file system, file status
11546 @item @emph{Description}:
11547 This function returns information about a file. No permissions are required on
11548 the file itself, but execute (search) permission is required on all of the
11549 directories in path that lead to the file.
11551 The elements that are obtained and stored in the array @code{VALUES}:
11552 @multitable @columnfractions .15 .70
11553 @item @code{VALUES(1)} @tab Device ID
11554 @item @code{VALUES(2)} @tab Inode number
11555 @item @code{VALUES(3)} @tab File mode
11556 @item @code{VALUES(4)} @tab Number of links
11557 @item @code{VALUES(5)} @tab Owner's uid
11558 @item @code{VALUES(6)} @tab Owner's gid
11559 @item @code{VALUES(7)} @tab ID of device containing directory entry for file (0 if not available)
11560 @item @code{VALUES(8)} @tab File size (bytes)
11561 @item @code{VALUES(9)} @tab Last access time
11562 @item @code{VALUES(10)} @tab Last modification time
11563 @item @code{VALUES(11)} @tab Last file status change time
11564 @item @code{VALUES(12)} @tab Preferred I/O block size (-1 if not available)
11565 @item @code{VALUES(13)} @tab Number of blocks allocated (-1 if not available)
11568 Not all these elements are relevant on all systems.
11569 If an element is not relevant, it is returned as 0.
11571 This intrinsic is provided in both subroutine and function forms; however,
11572 only one form can be used in any given program unit.
11574 @item @emph{Standard}:
11577 @item @emph{Class}:
11578 Subroutine, function
11580 @item @emph{Syntax}:
11581 @multitable @columnfractions .80
11582 @item @code{CALL STAT(NAME, VALUES [, STATUS])}
11583 @item @code{STATUS = STAT(NAME, VALUES)}
11586 @item @emph{Arguments}:
11587 @multitable @columnfractions .15 .70
11588 @item @var{NAME} @tab The type shall be @code{CHARACTER}, of the
11589 default kind and a valid path within the file system.
11590 @item @var{VALUES} @tab The type shall be @code{INTEGER(4), DIMENSION(13)}.
11591 @item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER(4)}. Returns 0
11592 on success and a system specific error code otherwise.
11595 @item @emph{Example}:
11598 INTEGER, DIMENSION(13) :: buff
11601 CALL STAT("/etc/passwd", buff, status)
11603 IF (status == 0) THEN
11604 WRITE (*, FMT="('Device ID:', T30, I19)") buff(1)
11605 WRITE (*, FMT="('Inode number:', T30, I19)") buff(2)
11606 WRITE (*, FMT="('File mode (octal):', T30, O19)") buff(3)
11607 WRITE (*, FMT="('Number of links:', T30, I19)") buff(4)
11608 WRITE (*, FMT="('Owner''s uid:', T30, I19)") buff(5)
11609 WRITE (*, FMT="('Owner''s gid:', T30, I19)") buff(6)
11610 WRITE (*, FMT="('Device where located:', T30, I19)") buff(7)
11611 WRITE (*, FMT="('File size:', T30, I19)") buff(8)
11612 WRITE (*, FMT="('Last access time:', T30, A19)") CTIME(buff(9))
11613 WRITE (*, FMT="('Last modification time', T30, A19)") CTIME(buff(10))
11614 WRITE (*, FMT="('Last status change time:', T30, A19)") CTIME(buff(11))
11615 WRITE (*, FMT="('Preferred block size:', T30, I19)") buff(12)
11616 WRITE (*, FMT="('No. of blocks allocated:', T30, I19)") buff(13)
11621 @item @emph{See also}:
11622 To stat an open file: @ref{FSTAT}, to stat a link: @ref{LSTAT}
11628 @section @code{STORAGE_SIZE} --- Storage size in bits
11629 @fnindex STORAGE_SIZE
11630 @cindex storage size
11633 @item @emph{Description}:
11634 Returns the storage size of argument @var{A} in bits.
11635 @item @emph{Standard}:
11636 Fortran 2008 and later
11637 @item @emph{Class}:
11639 @item @emph{Syntax}:
11640 @code{RESULT = STORAGE_SIZE(A [, KIND])}
11642 @item @emph{Arguments}:
11643 @multitable @columnfractions .15 .70
11644 @item @var{A} @tab Shall be a scalar or array of any type.
11645 @item @var{KIND} @tab (Optional) shall be a scalar integer constant expression.
11648 @item @emph{Return Value}:
11649 The result is a scalar integer with the kind type parameter specified by KIND (or default integer type if KIND is missing). The result value is the size expressed in bits for an element of an array that
11650 has the dynamic type and type parameters of A.
11652 @item @emph{See also}:
11653 @ref{C_SIZEOF}, @ref{SIZEOF}
11659 @section @code{SUM} --- Sum of array elements
11662 @cindex array, add elements
11663 @cindex array, conditionally add elements
11664 @cindex sum array elements
11667 @item @emph{Description}:
11668 Adds the elements of @var{ARRAY} along dimension @var{DIM} if
11669 the corresponding element in @var{MASK} is @code{TRUE}.
11671 @item @emph{Standard}:
11672 Fortran 95 and later
11674 @item @emph{Class}:
11675 Transformational function
11677 @item @emph{Syntax}:
11678 @multitable @columnfractions .80
11679 @item @code{RESULT = SUM(ARRAY[, MASK])}
11680 @item @code{RESULT = SUM(ARRAY, DIM[, MASK])}
11683 @item @emph{Arguments}:
11684 @multitable @columnfractions .15 .70
11685 @item @var{ARRAY} @tab Shall be an array of type @code{INTEGER},
11686 @code{REAL} or @code{COMPLEX}.
11687 @item @var{DIM} @tab (Optional) shall be a scalar of type
11688 @code{INTEGER} with a value in the range from 1 to n, where n
11689 equals the rank of @var{ARRAY}.
11690 @item @var{MASK} @tab (Optional) shall be of type @code{LOGICAL}
11691 and either be a scalar or an array of the same shape as @var{ARRAY}.
11694 @item @emph{Return value}:
11695 The result is of the same type as @var{ARRAY}.
11697 If @var{DIM} is absent, a scalar with the sum of all elements in @var{ARRAY}
11698 is returned. Otherwise, an array of rank n-1, where n equals the rank of
11699 @var{ARRAY}, and a shape similar to that of @var{ARRAY} with dimension @var{DIM}
11700 dropped is returned.
11702 @item @emph{Example}:
11705 INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /)
11706 print *, SUM(x) ! all elements, sum = 15
11707 print *, SUM(x, MASK=MOD(x, 2)==1) ! odd elements, sum = 9
11711 @item @emph{See also}:
11718 @section @code{SYMLNK} --- Create a symbolic link
11720 @cindex file system, create link
11721 @cindex file system, soft link
11724 @item @emph{Description}:
11725 Makes a symbolic link from file @var{PATH1} to @var{PATH2}. A null
11726 character (@code{CHAR(0)}) can be used to mark the end of the names in
11727 @var{PATH1} and @var{PATH2}; otherwise, trailing blanks in the file
11728 names are ignored. If the @var{STATUS} argument is supplied, it
11729 contains 0 on success or a nonzero error code upon return; see
11730 @code{symlink(2)}. If the system does not supply @code{symlink(2)},
11731 @code{ENOSYS} is returned.
11733 This intrinsic is provided in both subroutine and function forms;
11734 however, only one form can be used in any given program unit.
11736 @item @emph{Standard}:
11739 @item @emph{Class}:
11740 Subroutine, function
11742 @item @emph{Syntax}:
11743 @multitable @columnfractions .80
11744 @item @code{CALL SYMLNK(PATH1, PATH2 [, STATUS])}
11745 @item @code{STATUS = SYMLNK(PATH1, PATH2)}
11748 @item @emph{Arguments}:
11749 @multitable @columnfractions .15 .70
11750 @item @var{PATH1} @tab Shall be of default @code{CHARACTER} type.
11751 @item @var{PATH2} @tab Shall be of default @code{CHARACTER} type.
11752 @item @var{STATUS} @tab (Optional) Shall be of default @code{INTEGER} type.
11755 @item @emph{See also}:
11756 @ref{LINK}, @ref{UNLINK}
11763 @section @code{SYSTEM} --- Execute a shell command
11765 @cindex system, system call
11768 @item @emph{Description}:
11769 Passes the command @var{COMMAND} to a shell (see @code{system(3)}). If
11770 argument @var{STATUS} is present, it contains the value returned by
11771 @code{system(3)}, which is presumably 0 if the shell command succeeded.
11772 Note that which shell is used to invoke the command is system-dependent
11773 and environment-dependent.
11775 This intrinsic is provided in both subroutine and function forms;
11776 however, only one form can be used in any given program unit.
11778 @item @emph{Standard}:
11781 @item @emph{Class}:
11782 Subroutine, function
11784 @item @emph{Syntax}:
11785 @multitable @columnfractions .80
11786 @item @code{CALL SYSTEM(COMMAND [, STATUS])}
11787 @item @code{STATUS = SYSTEM(COMMAND)}
11790 @item @emph{Arguments}:
11791 @multitable @columnfractions .15 .70
11792 @item @var{COMMAND} @tab Shall be of default @code{CHARACTER} type.
11793 @item @var{STATUS} @tab (Optional) Shall be of default @code{INTEGER} type.
11796 @item @emph{See also}:
11797 @ref{EXECUTE_COMMAND_LINE}, which is part of the Fortran 2008 standard
11798 and should considered in new code for future portability.
11804 @section @code{SYSTEM_CLOCK} --- Time function
11805 @fnindex SYSTEM_CLOCK
11806 @cindex time, clock ticks
11807 @cindex clock ticks
11810 @item @emph{Description}:
11811 Determines the @var{COUNT} of milliseconds of wall clock time since
11812 the Epoch (00:00:00 UTC, January 1, 1970) modulo @var{COUNT_MAX},
11813 @var{COUNT_RATE} determines the number of clock ticks per second.
11814 @var{COUNT_RATE} and @var{COUNT_MAX} are constant and specific to
11815 @command{gfortran}.
11817 If there is no clock, @var{COUNT} is set to @code{-HUGE(COUNT)}, and
11818 @var{COUNT_RATE} and @var{COUNT_MAX} are set to zero
11820 @item @emph{Standard}:
11821 Fortran 95 and later
11823 @item @emph{Class}:
11826 @item @emph{Syntax}:
11827 @code{CALL SYSTEM_CLOCK([COUNT, COUNT_RATE, COUNT_MAX])}
11829 @item @emph{Arguments}:
11830 @multitable @columnfractions .15 .70
11831 @item @var{COUNT} @tab (Optional) shall be a scalar of type default
11832 @code{INTEGER} with @code{INTENT(OUT)}.
11833 @item @var{COUNT_RATE} @tab (Optional) shall be a scalar of type default
11834 @code{INTEGER} with @code{INTENT(OUT)}.
11835 @item @var{COUNT_MAX} @tab (Optional) shall be a scalar of type default
11836 @code{INTEGER} with @code{INTENT(OUT)}.
11839 @item @emph{Example}:
11841 PROGRAM test_system_clock
11842 INTEGER :: count, count_rate, count_max
11843 CALL SYSTEM_CLOCK(count, count_rate, count_max)
11844 WRITE(*,*) count, count_rate, count_max
11848 @item @emph{See also}:
11849 @ref{DATE_AND_TIME}, @ref{CPU_TIME}
11855 @section @code{TAN} --- Tangent function
11858 @cindex trigonometric function, tangent
11862 @item @emph{Description}:
11863 @code{TAN(X)} computes the tangent of @var{X}.
11865 @item @emph{Standard}:
11866 Fortran 77 and later, for a complex argument Fortran 2008 or later
11868 @item @emph{Class}:
11871 @item @emph{Syntax}:
11872 @code{RESULT = TAN(X)}
11874 @item @emph{Arguments}:
11875 @multitable @columnfractions .15 .70
11876 @item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
11879 @item @emph{Return value}:
11880 The return value has same type and kind as @var{X}.
11882 @item @emph{Example}:
11885 real(8) :: x = 0.165_8
11887 end program test_tan
11890 @item @emph{Specific names}:
11891 @multitable @columnfractions .20 .20 .20 .25
11892 @item Name @tab Argument @tab Return type @tab Standard
11893 @item @code{TAN(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 95 and later
11894 @item @code{DTAN(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 95 and later
11897 @item @emph{See also}:
11904 @section @code{TANH} --- Hyperbolic tangent function
11907 @cindex hyperbolic tangent
11908 @cindex hyperbolic function, tangent
11909 @cindex tangent, hyperbolic
11912 @item @emph{Description}:
11913 @code{TANH(X)} computes the hyperbolic tangent of @var{X}.
11915 @item @emph{Standard}:
11916 Fortran 77 and later, for a complex argument Fortran 2008 or later
11918 @item @emph{Class}:
11921 @item @emph{Syntax}:
11924 @item @emph{Arguments}:
11925 @multitable @columnfractions .15 .70
11926 @item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
11929 @item @emph{Return value}:
11930 The return value has same type and kind as @var{X}. If @var{X} is
11931 complex, the imaginary part of the result is in radians. If @var{X}
11932 is @code{REAL}, the return value lies in the range
11933 @math{ - 1 \leq tanh(x) \leq 1 }.
11935 @item @emph{Example}:
11938 real(8) :: x = 2.1_8
11940 end program test_tanh
11943 @item @emph{Specific names}:
11944 @multitable @columnfractions .20 .20 .20 .25
11945 @item Name @tab Argument @tab Return type @tab Standard
11946 @item @code{TANH(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)} @tab Fortran 95 and later
11947 @item @code{DTANH(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)} @tab Fortran 95 and later
11950 @item @emph{See also}:
11957 @section @code{THIS_IMAGE} --- Function that returns the cosubscript index of this image
11958 @fnindex THIS_IMAGE
11959 @cindex coarray, @code{THIS_IMAGE}
11960 @cindex images, index of this image
11963 @item @emph{Description}:
11964 Returns the cosubscript for this image.
11966 @item @emph{Standard}:
11967 Fortran 2008 and later
11969 @item @emph{Class}:
11970 Transformational function
11972 @item @emph{Syntax}:
11973 @multitable @columnfractions .80
11974 @item @code{RESULT = THIS_IMAGE()}
11975 @item @code{RESULT = THIS_IMAGE(COARRAY [, DIM])}
11978 @item @emph{Arguments}:
11979 @multitable @columnfractions .15 .70
11980 @item @var{COARRAY} @tab Coarray of any type (optional; if @var{DIM}
11981 present, required).
11982 @item @var{DIM} @tab default integer scalar (optional). If present,
11983 @var{DIM} shall be between one and the corank of @var{COARRAY}.
11987 @item @emph{Return value}:
11988 Default integer. If @var{COARRAY} is not present, it is scalar and its value
11989 is the index of the invoking image. Otherwise, if @var{DIM} is not present,
11990 a rank-1 array with corank elements is returned, containing the cosubscripts
11991 for @var{COARRAY} specifying the invoking image. If @var{DIM} is present,
11992 a scalar is returned, with the value of the @var{DIM} element of
11993 @code{THIS_IMAGE(COARRAY)}.
11995 @item @emph{Example}:
11997 INTEGER :: value[*]
11999 value = THIS_IMAGE()
12001 IF (THIS_IMAGE() == 1) THEN
12002 DO i = 1, NUM_IMAGES()
12003 WRITE(*,'(2(a,i0))') 'value[', i, '] is ', value[i]
12008 @item @emph{See also}:
12009 @ref{NUM_IMAGES}, @ref{IMAGE_INDEX}
12015 @section @code{TIME} --- Time function
12017 @cindex time, current
12018 @cindex current time
12021 @item @emph{Description}:
12022 Returns the current time encoded as an integer (in the manner of the
12023 UNIX function @code{time(3)}). This value is suitable for passing to
12024 @code{CTIME()}, @code{GMTIME()}, and @code{LTIME()}.
12026 This intrinsic is not fully portable, such as to systems with 32-bit
12027 @code{INTEGER} types but supporting times wider than 32 bits. Therefore,
12028 the values returned by this intrinsic might be, or become, negative, or
12029 numerically less than previous values, during a single run of the
12032 See @ref{TIME8}, for information on a similar intrinsic that might be
12033 portable to more GNU Fortran implementations, though to fewer Fortran
12036 @item @emph{Standard}:
12039 @item @emph{Class}:
12042 @item @emph{Syntax}:
12043 @code{RESULT = TIME()}
12045 @item @emph{Return value}:
12046 The return value is a scalar of type @code{INTEGER(4)}.
12048 @item @emph{See also}:
12049 @ref{CTIME}, @ref{GMTIME}, @ref{LTIME}, @ref{MCLOCK}, @ref{TIME8}
12056 @section @code{TIME8} --- Time function (64-bit)
12058 @cindex time, current
12059 @cindex current time
12062 @item @emph{Description}:
12063 Returns the current time encoded as an integer (in the manner of the
12064 UNIX function @code{time(3)}). This value is suitable for passing to
12065 @code{CTIME()}, @code{GMTIME()}, and @code{LTIME()}.
12067 @emph{Warning:} this intrinsic does not increase the range of the timing
12068 values over that returned by @code{time(3)}. On a system with a 32-bit
12069 @code{time(3)}, @code{TIME8()} will return a 32-bit value, even though
12070 it is converted to a 64-bit @code{INTEGER(8)} value. That means
12071 overflows of the 32-bit value can still occur. Therefore, the values
12072 returned by this intrinsic might be or become negative or numerically
12073 less than previous values during a single run of the compiled program.
12075 @item @emph{Standard}:
12078 @item @emph{Class}:
12081 @item @emph{Syntax}:
12082 @code{RESULT = TIME8()}
12084 @item @emph{Return value}:
12085 The return value is a scalar of type @code{INTEGER(8)}.
12087 @item @emph{See also}:
12088 @ref{CTIME}, @ref{GMTIME}, @ref{LTIME}, @ref{MCLOCK8}, @ref{TIME}
12095 @section @code{TINY} --- Smallest positive number of a real kind
12097 @cindex limits, smallest number
12098 @cindex model representation, smallest number
12101 @item @emph{Description}:
12102 @code{TINY(X)} returns the smallest positive (non zero) number
12103 in the model of the type of @code{X}.
12105 @item @emph{Standard}:
12106 Fortran 95 and later
12108 @item @emph{Class}:
12111 @item @emph{Syntax}:
12112 @code{RESULT = TINY(X)}
12114 @item @emph{Arguments}:
12115 @multitable @columnfractions .15 .70
12116 @item @var{X} @tab Shall be of type @code{REAL}.
12119 @item @emph{Return value}:
12120 The return value is of the same type and kind as @var{X}
12122 @item @emph{Example}:
12123 See @code{HUGE} for an example.
12129 @section @code{TRAILZ} --- Number of trailing zero bits of an integer
12134 @item @emph{Description}:
12135 @code{TRAILZ} returns the number of trailing zero bits of an integer.
12137 @item @emph{Standard}:
12138 Fortran 2008 and later
12140 @item @emph{Class}:
12143 @item @emph{Syntax}:
12144 @code{RESULT = TRAILZ(I)}
12146 @item @emph{Arguments}:
12147 @multitable @columnfractions .15 .70
12148 @item @var{I} @tab Shall be of type @code{INTEGER}.
12151 @item @emph{Return value}:
12152 The type of the return value is the default @code{INTEGER}.
12153 If all the bits of @code{I} are zero, the result value is @code{BIT_SIZE(I)}.
12155 @item @emph{Example}:
12157 PROGRAM test_trailz
12158 WRITE (*,*) TRAILZ(8) ! prints 3
12162 @item @emph{See also}:
12163 @ref{BIT_SIZE}, @ref{LEADZ}, @ref{POPPAR}, @ref{POPCNT}
12169 @section @code{TRANSFER} --- Transfer bit patterns
12175 @item @emph{Description}:
12176 Interprets the bitwise representation of @var{SOURCE} in memory as if it
12177 is the representation of a variable or array of the same type and type
12178 parameters as @var{MOLD}.
12180 This is approximately equivalent to the C concept of @emph{casting} one
12183 @item @emph{Standard}:
12184 Fortran 95 and later
12186 @item @emph{Class}:
12187 Transformational function
12189 @item @emph{Syntax}:
12190 @code{RESULT = TRANSFER(SOURCE, MOLD[, SIZE])}
12192 @item @emph{Arguments}:
12193 @multitable @columnfractions .15 .70
12194 @item @var{SOURCE} @tab Shall be a scalar or an array of any type.
12195 @item @var{MOLD} @tab Shall be a scalar or an array of any type.
12196 @item @var{SIZE} @tab (Optional) shall be a scalar of type
12200 @item @emph{Return value}:
12201 The result has the same type as @var{MOLD}, with the bit level
12202 representation of @var{SOURCE}. If @var{SIZE} is present, the result is
12203 a one-dimensional array of length @var{SIZE}. If @var{SIZE} is absent
12204 but @var{MOLD} is an array (of any size or shape), the result is a one-
12205 dimensional array of the minimum length needed to contain the entirety
12206 of the bitwise representation of @var{SOURCE}. If @var{SIZE} is absent
12207 and @var{MOLD} is a scalar, the result is a scalar.
12209 If the bitwise representation of the result is longer than that of
12210 @var{SOURCE}, then the leading bits of the result correspond to those of
12211 @var{SOURCE} and any trailing bits are filled arbitrarily.
12213 When the resulting bit representation does not correspond to a valid
12214 representation of a variable of the same type as @var{MOLD}, the results
12215 are undefined, and subsequent operations on the result cannot be
12216 guaranteed to produce sensible behavior. For example, it is possible to
12217 create @code{LOGICAL} variables for which @code{@var{VAR}} and
12218 @code{.NOT.@var{VAR}} both appear to be true.
12220 @item @emph{Example}:
12222 PROGRAM test_transfer
12223 integer :: x = 2143289344
12224 print *, transfer(x, 1.0) ! prints "NaN" on i686
12232 @section @code{TRANSPOSE} --- Transpose an array of rank two
12234 @cindex array, transpose
12235 @cindex matrix, transpose
12239 @item @emph{Description}:
12240 Transpose an array of rank two. Element (i, j) of the result has the value
12241 @code{MATRIX(j, i)}, for all i, j.
12243 @item @emph{Standard}:
12244 Fortran 95 and later
12246 @item @emph{Class}:
12247 Transformational function
12249 @item @emph{Syntax}:
12250 @code{RESULT = TRANSPOSE(MATRIX)}
12252 @item @emph{Arguments}:
12253 @multitable @columnfractions .15 .70
12254 @item @var{MATRIX} @tab Shall be an array of any type and have a rank of two.
12257 @item @emph{Return value}:
12258 The result has the same type as @var{MATRIX}, and has shape
12259 @code{(/ m, n /)} if @var{MATRIX} has shape @code{(/ n, m /)}.
12265 @section @code{TRIM} --- Remove trailing blank characters of a string
12267 @cindex string, remove trailing whitespace
12270 @item @emph{Description}:
12271 Removes trailing blank characters of a string.
12273 @item @emph{Standard}:
12274 Fortran 95 and later
12276 @item @emph{Class}:
12277 Transformational function
12279 @item @emph{Syntax}:
12280 @code{RESULT = TRIM(STRING)}
12282 @item @emph{Arguments}:
12283 @multitable @columnfractions .15 .70
12284 @item @var{STRING} @tab Shall be a scalar of type @code{CHARACTER}.
12287 @item @emph{Return value}:
12288 A scalar of type @code{CHARACTER} which length is that of @var{STRING}
12289 less the number of trailing blanks.
12291 @item @emph{Example}:
12294 CHARACTER(len=10), PARAMETER :: s = "GFORTRAN "
12295 WRITE(*,*) LEN(s), LEN(TRIM(s)) ! "10 8", with/without trailing blanks
12299 @item @emph{See also}:
12300 @ref{ADJUSTL}, @ref{ADJUSTR}
12306 @section @code{TTYNAM} --- Get the name of a terminal device.
12308 @cindex system, terminal
12311 @item @emph{Description}:
12312 Get the name of a terminal device. For more information,
12313 see @code{ttyname(3)}.
12315 This intrinsic is provided in both subroutine and function forms;
12316 however, only one form can be used in any given program unit.
12318 @item @emph{Standard}:
12321 @item @emph{Class}:
12322 Subroutine, function
12324 @item @emph{Syntax}:
12325 @multitable @columnfractions .80
12326 @item @code{CALL TTYNAM(UNIT, NAME)}
12327 @item @code{NAME = TTYNAM(UNIT)}
12330 @item @emph{Arguments}:
12331 @multitable @columnfractions .15 .70
12332 @item @var{UNIT} @tab Shall be a scalar @code{INTEGER}.
12333 @item @var{NAME} @tab Shall be of type @code{CHARACTER}.
12336 @item @emph{Example}:
12338 PROGRAM test_ttynam
12341 IF (isatty(unit=unit)) write(*,*) ttynam(unit)
12346 @item @emph{See also}:
12353 @section @code{UBOUND} --- Upper dimension bounds of an array
12355 @cindex array, upper bound
12358 @item @emph{Description}:
12359 Returns the upper bounds of an array, or a single upper bound
12360 along the @var{DIM} dimension.
12361 @item @emph{Standard}:
12362 Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
12364 @item @emph{Class}:
12367 @item @emph{Syntax}:
12368 @code{RESULT = UBOUND(ARRAY [, DIM [, KIND]])}
12370 @item @emph{Arguments}:
12371 @multitable @columnfractions .15 .70
12372 @item @var{ARRAY} @tab Shall be an array, of any type.
12373 @item @var{DIM} @tab (Optional) Shall be a scalar @code{INTEGER}.
12374 @item @var{KIND}@tab (Optional) An @code{INTEGER} initialization
12375 expression indicating the kind parameter of the result.
12378 @item @emph{Return value}:
12379 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
12380 @var{KIND} is absent, the return value is of default integer kind.
12381 If @var{DIM} is absent, the result is an array of the upper bounds of
12382 @var{ARRAY}. If @var{DIM} is present, the result is a scalar
12383 corresponding to the upper bound of the array along that dimension. If
12384 @var{ARRAY} is an expression rather than a whole array or array
12385 structure component, or if it has a zero extent along the relevant
12386 dimension, the upper bound is taken to be the number of elements along
12387 the relevant dimension.
12389 @item @emph{See also}:
12390 @ref{LBOUND}, @ref{LCOBOUND}
12396 @section @code{UCOBOUND} --- Upper codimension bounds of an array
12398 @cindex coarray, upper bound
12401 @item @emph{Description}:
12402 Returns the upper cobounds of a coarray, or a single upper cobound
12403 along the @var{DIM} codimension.
12404 @item @emph{Standard}:
12405 Fortran 2008 and later
12407 @item @emph{Class}:
12410 @item @emph{Syntax}:
12411 @code{RESULT = UCOBOUND(COARRAY [, DIM [, KIND]])}
12413 @item @emph{Arguments}:
12414 @multitable @columnfractions .15 .70
12415 @item @var{ARRAY} @tab Shall be an coarray, of any type.
12416 @item @var{DIM} @tab (Optional) Shall be a scalar @code{INTEGER}.
12417 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
12418 expression indicating the kind parameter of the result.
12421 @item @emph{Return value}:
12422 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
12423 @var{KIND} is absent, the return value is of default integer kind.
12424 If @var{DIM} is absent, the result is an array of the lower cobounds of
12425 @var{COARRAY}. If @var{DIM} is present, the result is a scalar
12426 corresponding to the lower cobound of the array along that codimension.
12428 @item @emph{See also}:
12429 @ref{LCOBOUND}, @ref{LBOUND}
12435 @section @code{UMASK} --- Set the file creation mask
12437 @cindex file system, file creation mask
12440 @item @emph{Description}:
12441 Sets the file creation mask to @var{MASK}. If called as a function, it
12442 returns the old value. If called as a subroutine and argument @var{OLD}
12443 if it is supplied, it is set to the old value. See @code{umask(2)}.
12445 @item @emph{Standard}:
12448 @item @emph{Class}:
12449 Subroutine, function
12451 @item @emph{Syntax}:
12452 @multitable @columnfractions .80
12453 @item @code{CALL UMASK(MASK [, OLD])}
12454 @item @code{OLD = UMASK(MASK)}
12457 @item @emph{Arguments}:
12458 @multitable @columnfractions .15 .70
12459 @item @var{MASK} @tab Shall be a scalar of type @code{INTEGER}.
12460 @item @var{OLD} @tab (Optional) Shall be a scalar of type
12469 @section @code{UNLINK} --- Remove a file from the file system
12471 @cindex file system, remove file
12474 @item @emph{Description}:
12475 Unlinks the file @var{PATH}. A null character (@code{CHAR(0)}) can be
12476 used to mark the end of the name in @var{PATH}; otherwise, trailing
12477 blanks in the file name are ignored. If the @var{STATUS} argument is
12478 supplied, it contains 0 on success or a nonzero error code upon return;
12479 see @code{unlink(2)}.
12481 This intrinsic is provided in both subroutine and function forms;
12482 however, only one form can be used in any given program unit.
12484 @item @emph{Standard}:
12487 @item @emph{Class}:
12488 Subroutine, function
12490 @item @emph{Syntax}:
12491 @multitable @columnfractions .80
12492 @item @code{CALL UNLINK(PATH [, STATUS])}
12493 @item @code{STATUS = UNLINK(PATH)}
12496 @item @emph{Arguments}:
12497 @multitable @columnfractions .15 .70
12498 @item @var{PATH} @tab Shall be of default @code{CHARACTER} type.
12499 @item @var{STATUS} @tab (Optional) Shall be of default @code{INTEGER} type.
12502 @item @emph{See also}:
12503 @ref{LINK}, @ref{SYMLNK}
12509 @section @code{UNPACK} --- Unpack an array of rank one into an array
12511 @cindex array, unpacking
12512 @cindex array, increase dimension
12513 @cindex array, scatter elements
12516 @item @emph{Description}:
12517 Store the elements of @var{VECTOR} in an array of higher rank.
12519 @item @emph{Standard}:
12520 Fortran 95 and later
12522 @item @emph{Class}:
12523 Transformational function
12525 @item @emph{Syntax}:
12526 @code{RESULT = UNPACK(VECTOR, MASK, FIELD)}
12528 @item @emph{Arguments}:
12529 @multitable @columnfractions .15 .70
12530 @item @var{VECTOR} @tab Shall be an array of any type and rank one. It
12531 shall have at least as many elements as @var{MASK} has @code{TRUE} values.
12532 @item @var{MASK} @tab Shall be an array of type @code{LOGICAL}.
12533 @item @var{FIELD} @tab Shall be of the same type as @var{VECTOR} and have
12534 the same shape as @var{MASK}.
12537 @item @emph{Return value}:
12538 The resulting array corresponds to @var{FIELD} with @code{TRUE} elements
12539 of @var{MASK} replaced by values from @var{VECTOR} in array element order.
12541 @item @emph{Example}:
12543 PROGRAM test_unpack
12544 integer :: vector(2) = (/1,1/)
12545 logical :: mask(4) = (/ .TRUE., .FALSE., .FALSE., .TRUE. /)
12546 integer :: field(2,2) = 0, unity(2,2)
12548 ! result: unity matrix
12549 unity = unpack(vector, reshape(mask, (/2,2/)), field)
12553 @item @emph{See also}:
12554 @ref{PACK}, @ref{SPREAD}
12560 @section @code{VERIFY} --- Scan a string for the absence of a set of characters
12562 @cindex string, find missing set
12565 @item @emph{Description}:
12566 Verifies that all the characters in a @var{SET} are present in a @var{STRING}.
12568 If @var{BACK} is either absent or equals @code{FALSE}, this function
12569 returns the position of the leftmost character of @var{STRING} that is
12570 not in @var{SET}. If @var{BACK} equals @code{TRUE}, the rightmost position
12571 is returned. If all characters of @var{SET} are found in @var{STRING}, the
12574 @item @emph{Standard}:
12575 Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
12577 @item @emph{Class}:
12580 @item @emph{Syntax}:
12581 @code{RESULT = VERIFY(STRING, SET[, BACK [, KIND]])}
12583 @item @emph{Arguments}:
12584 @multitable @columnfractions .15 .70
12585 @item @var{STRING} @tab Shall be of type @code{CHARACTER}.
12586 @item @var{SET} @tab Shall be of type @code{CHARACTER}.
12587 @item @var{BACK} @tab (Optional) shall be of type @code{LOGICAL}.
12588 @item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
12589 expression indicating the kind parameter of the result.
12592 @item @emph{Return value}:
12593 The return value is of type @code{INTEGER} and of kind @var{KIND}. If
12594 @var{KIND} is absent, the return value is of default integer kind.
12596 @item @emph{Example}:
12598 PROGRAM test_verify
12599 WRITE(*,*) VERIFY("FORTRAN", "AO") ! 1, found 'F'
12600 WRITE(*,*) VERIFY("FORTRAN", "FOO") ! 3, found 'R'
12601 WRITE(*,*) VERIFY("FORTRAN", "C++") ! 1, found 'F'
12602 WRITE(*,*) VERIFY("FORTRAN", "C++", .TRUE.) ! 7, found 'N'
12603 WRITE(*,*) VERIFY("FORTRAN", "FORTRAN") ! 0' found none
12607 @item @emph{See also}:
12608 @ref{SCAN}, @ref{INDEX intrinsic}
12614 @section @code{XOR} --- Bitwise logical exclusive OR
12616 @cindex bitwise logical exclusive or
12617 @cindex logical exclusive or, bitwise
12620 @item @emph{Description}:
12621 Bitwise logical exclusive or.
12623 This intrinsic routine is provided for backwards compatibility with
12624 GNU Fortran 77. For integer arguments, programmers should consider
12625 the use of the @ref{IEOR} intrinsic and for logical arguments the
12626 @code{.NEQV.} operator, which are both defined by the Fortran standard.
12628 @item @emph{Standard}:
12631 @item @emph{Class}:
12634 @item @emph{Syntax}:
12635 @code{RESULT = XOR(I, J)}
12637 @item @emph{Arguments}:
12638 @multitable @columnfractions .15 .70
12639 @item @var{I} @tab The type shall be either a scalar @code{INTEGER}
12640 type or a scalar @code{LOGICAL} type.
12641 @item @var{J} @tab The type shall be the same as the type of @var{I}.
12644 @item @emph{Return value}:
12645 The return type is either a scalar @code{INTEGER} or a scalar
12646 @code{LOGICAL}. If the kind type parameters differ, then the
12647 smaller kind type is implicitly converted to larger kind, and the
12648 return has the larger kind.
12650 @item @emph{Example}:
12653 LOGICAL :: T = .TRUE., F = .FALSE.
12655 DATA a / Z'F' /, b / Z'3' /
12657 WRITE (*,*) XOR(T, T), XOR(T, F), XOR(F, T), XOR(F, F)
12658 WRITE (*,*) XOR(a, b)
12662 @item @emph{See also}:
12663 Fortran 95 elemental function: @ref{IEOR}
12668 @node Intrinsic Modules
12669 @chapter Intrinsic Modules
12670 @cindex intrinsic Modules
12673 * ISO_FORTRAN_ENV::
12675 * OpenMP Modules OMP_LIB and OMP_LIB_KINDS::
12678 @node ISO_FORTRAN_ENV
12679 @section @code{ISO_FORTRAN_ENV}
12681 @item @emph{Standard}:
12682 Fortran 2003 and later, except when otherwise noted
12685 The @code{ISO_FORTRAN_ENV} module provides the following scalar default-integer
12689 @item @code{ATOMIC_INT_KIND}:
12690 Default-kind integer constant to be used as kind parameter when defining
12691 integer variables used in atomic operations. (Fortran 2008 or later.)
12693 @item @code{ATOMIC_LOGICAL_KIND}:
12694 Default-kind integer constant to be used as kind parameter when defining
12695 logical variables used in atomic operations. (Fortran 2008 or later.)
12697 @item @code{CHARACTER_KINDS}:
12698 Default-kind integer constant array of rank one containing the supported kind
12699 parameters of the @code{CHARACTER} type. (Fortran 2008 or later.)
12701 @item @code{CHARACTER_STORAGE_SIZE}:
12702 Size in bits of the character storage unit.
12704 @item @code{ERROR_UNIT}:
12705 Identifies the preconnected unit used for error reporting.
12707 @item @code{FILE_STORAGE_SIZE}:
12708 Size in bits of the file-storage unit.
12710 @item @code{INPUT_UNIT}:
12711 Identifies the preconnected unit identified by the asterisk
12712 (@code{*}) in @code{READ} statement.
12714 @item @code{INT8}, @code{INT16}, @code{INT32}, @code{INT64}:
12715 Kind type parameters to specify an INTEGER type with a storage
12716 size of 16, 32, and 64 bits. It is negative if a target platform
12717 does not support the particular kind. (Fortran 2008 or later.)
12719 @item @code{INTEGER_KINDS}:
12720 Default-kind integer constant array of rank one containing the supported kind
12721 parameters of the @code{INTEGER} type. (Fortran 2008 or later.)
12723 @item @code{IOSTAT_END}:
12724 The value assigned to the variable passed to the @code{IOSTAT=} specifier of
12725 an input/output statement if an end-of-file condition occurred.
12727 @item @code{IOSTAT_EOR}:
12728 The value assigned to the variable passed to the @code{IOSTAT=} specifier of
12729 an input/output statement if an end-of-record condition occurred.
12731 @item @code{IOSTAT_INQUIRE_INTERNAL_UNIT}:
12732 Scalar default-integer constant, used by @code{INQUIRE} for the
12733 @code{IOSTAT=} specifier to denote an that a unit number identifies an
12734 internal unit. (Fortran 2008 or later.)
12736 @item @code{NUMERIC_STORAGE_SIZE}:
12737 The size in bits of the numeric storage unit.
12739 @item @code{LOGICAL_KINDS}:
12740 Default-kind integer constant array of rank one containing the supported kind
12741 parameters of the @code{LOGICAL} type. (Fortran 2008 or later.)
12743 @item @code{OUTPUT_UNIT}:
12744 Identifies the preconnected unit identified by the asterisk
12745 (@code{*}) in @code{WRITE} statement.
12747 @item @code{REAL32}, @code{REAL64}, @code{REAL128}:
12748 Kind type parameters to specify a REAL type with a storage
12749 size of 32, 64, and 128 bits. It is negative if a target platform
12750 does not support the particular kind. (Fortran 2008 or later.)
12752 @item @code{REAL_KINDS}:
12753 Default-kind integer constant array of rank one containing the supported kind
12754 parameters of the @code{REAL} type. (Fortran 2008 or later.)
12756 @item @code{STAT_LOCKED}:
12757 Scalar default-integer constant used as STAT= return value by @code{LOCK} to
12758 denote that the lock variable is locked by the executing image. (Fortran 2008
12761 @item @code{STAT_LOCKED_OTHER_IMAGE}:
12762 Scalar default-integer constant used as STAT= return value by @code{UNLOCK} to
12763 denote that the lock variable is locked by another image. (Fortran 2008 or
12766 @item @code{STAT_STOPPED_IMAGE}:
12767 Positive, scalar default-integer constant used as STAT= return value if the
12768 argument in the statement requires synchronisation with an image, which has
12769 initiated the termination of the execution. (Fortran 2008 or later.)
12771 @item @code{STAT_UNLOCKED}:
12772 Scalar default-integer constant used as STAT= return value by @code{UNLOCK} to
12773 denote that the lock variable is unlocked. (Fortran 2008 or later.)
12776 The module also provides the following intrinsic procedures:
12777 @ref{COMPILER_OPTIONS} and @ref{COMPILER_VERSION}.
12781 @node ISO_C_BINDING
12782 @section @code{ISO_C_BINDING}
12784 @item @emph{Standard}:
12785 Fortran 2003 and later, GNU extensions
12788 The following intrinsic procedures are provided by the module; their
12789 definition can be found in the section Intrinsic Procedures of this
12793 @item @code{C_ASSOCIATED}
12794 @item @code{C_F_POINTER}
12795 @item @code{C_F_PROCPOINTER}
12796 @item @code{C_FUNLOC}
12798 @item @code{C_SIZEOF}
12800 @c TODO: Vertical spacing between C_FUNLOC and C_LOC wrong in PDF,
12801 @c don't really know why.
12803 The @code{ISO_C_BINDING} module provides the following named constants of
12804 type default integer, which can be used as KIND type parameters.
12806 In addition to the integer named constants required by the Fortran 2003
12807 standard, GNU Fortran provides as an extension named constants for the
12808 128-bit integer types supported by the C compiler: @code{C_INT128_T,
12809 C_INT_LEAST128_T, C_INT_FAST128_T}.
12811 @multitable @columnfractions .15 .35 .35 .35
12812 @item Fortran Type @tab Named constant @tab C type @tab Extension
12813 @item @code{INTEGER}@tab @code{C_INT} @tab @code{int}
12814 @item @code{INTEGER}@tab @code{C_SHORT} @tab @code{short int}
12815 @item @code{INTEGER}@tab @code{C_LONG} @tab @code{long int}
12816 @item @code{INTEGER}@tab @code{C_LONG_LONG} @tab @code{long long int}
12817 @item @code{INTEGER}@tab @code{C_SIGNED_CHAR} @tab @code{signed char}/@code{unsigned char}
12818 @item @code{INTEGER}@tab @code{C_SIZE_T} @tab @code{size_t}
12819 @item @code{INTEGER}@tab @code{C_INT8_T} @tab @code{int8_t}
12820 @item @code{INTEGER}@tab @code{C_INT16_T} @tab @code{int16_t}
12821 @item @code{INTEGER}@tab @code{C_INT32_T} @tab @code{int32_t}
12822 @item @code{INTEGER}@tab @code{C_INT64_T} @tab @code{int64_t}
12823 @item @code{INTEGER}@tab @code{C_INT128_T} @tab @code{int128_t} @tab Ext.
12824 @item @code{INTEGER}@tab @code{C_INT_LEAST8_T} @tab @code{int_least8_t}
12825 @item @code{INTEGER}@tab @code{C_INT_LEAST16_T} @tab @code{int_least16_t}
12826 @item @code{INTEGER}@tab @code{C_INT_LEAST32_T} @tab @code{int_least32_t}
12827 @item @code{INTEGER}@tab @code{C_INT_LEAST64_T} @tab @code{int_least64_t}
12828 @item @code{INTEGER}@tab @code{C_INT_LEAST128_T}@tab @code{int_least128_t} @tab Ext.
12829 @item @code{INTEGER}@tab @code{C_INT_FAST8_T} @tab @code{int_fast8_t}
12830 @item @code{INTEGER}@tab @code{C_INT_FAST16_T} @tab @code{int_fast16_t}
12831 @item @code{INTEGER}@tab @code{C_INT_FAST32_T} @tab @code{int_fast32_t}
12832 @item @code{INTEGER}@tab @code{C_INT_FAST64_T} @tab @code{int_fast64_t}
12833 @item @code{INTEGER}@tab @code{C_INT_FAST128_T} @tab @code{int_fast128_t} @tab Ext.
12834 @item @code{INTEGER}@tab @code{C_INTMAX_T} @tab @code{intmax_t}
12835 @item @code{INTEGER}@tab @code{C_INTPTR_T} @tab @code{intptr_t}
12836 @item @code{REAL} @tab @code{C_FLOAT} @tab @code{float}
12837 @item @code{REAL} @tab @code{C_DOUBLE} @tab @code{double}
12838 @item @code{REAL} @tab @code{C_LONG_DOUBLE} @tab @code{long double}
12839 @item @code{COMPLEX}@tab @code{C_FLOAT_COMPLEX} @tab @code{float _Complex}
12840 @item @code{COMPLEX}@tab @code{C_DOUBLE_COMPLEX}@tab @code{double _Complex}
12841 @item @code{COMPLEX}@tab @code{C_LONG_DOUBLE_COMPLEX}@tab @code{long double _Complex}
12842 @item @code{LOGICAL}@tab @code{C_BOOL} @tab @code{_Bool}
12843 @item @code{CHARACTER}@tab @code{C_CHAR} @tab @code{char}
12846 Additionally, the following parameters of type @code{CHARACTER(KIND=C_CHAR)}
12849 @multitable @columnfractions .20 .45 .15
12850 @item Name @tab C definition @tab Value
12851 @item @code{C_NULL_CHAR} @tab null character @tab @code{'\0'}
12852 @item @code{C_ALERT} @tab alert @tab @code{'\a'}
12853 @item @code{C_BACKSPACE} @tab backspace @tab @code{'\b'}
12854 @item @code{C_FORM_FEED} @tab form feed @tab @code{'\f'}
12855 @item @code{C_NEW_LINE} @tab new line @tab @code{'\n'}
12856 @item @code{C_CARRIAGE_RETURN} @tab carriage return @tab @code{'\r'}
12857 @item @code{C_HORIZONTAL_TAB} @tab horizontal tab @tab @code{'\t'}
12858 @item @code{C_VERTICAL_TAB} @tab vertical tab @tab @code{'\v'}
12861 Moreover, the following two named constants are defined:
12863 @multitable @columnfractions .20 .80
12864 @item Name @tab Type
12865 @item @code{C_NULL_PTR} @tab @code{C_PTR}
12866 @item @code{C_NULL_FUNPTR} @tab @code{C_FUNPTR}
12869 Both are equivalent to the value @code{NULL} in C.
12871 @node OpenMP Modules OMP_LIB and OMP_LIB_KINDS
12872 @section OpenMP Modules @code{OMP_LIB} and @code{OMP_LIB_KINDS}
12874 @item @emph{Standard}:
12875 OpenMP Application Program Interface v3.0
12879 The OpenMP Fortran runtime library routines are provided both in
12880 a form of two Fortran 90 modules, named @code{OMP_LIB} and
12881 @code{OMP_LIB_KINDS}, and in a form of a Fortran @code{include} file named
12882 @file{omp_lib.h}. The procedures provided by @code{OMP_LIB} can be found
12883 in the @ref{Top,,Introduction,libgomp,GNU OpenMP runtime library} manual,
12884 the named constants defined in the modules are listed
12887 For details refer to the actual
12888 @uref{http://www.openmp.org/mp-documents/spec30.pdf,
12889 OpenMP Application Program Interface v3.0}.
12891 @code{OMP_LIB_KINDS} provides the following scalar default-integer
12895 @item @code{omp_integer_kind}
12896 @item @code{omp_logical_kind}
12897 @item @code{omp_lock_kind}
12898 @item @code{omp_nest_lock_kind}
12899 @item @code{omp_sched_kind}
12902 @code{OMP_LIB} provides the scalar default-integer
12903 named constant @code{openmp_version} with a value of the form
12904 @var{yyyymm}, where @code{yyyy} is the year and @var{mm} the month
12905 of the OpenMP version; for OpenMP v3.0 the value is @code{200805}.
12907 And the following scalar integer named constants of the
12908 kind @code{omp_sched_kind}:
12911 @item @code{omp_sched_static}
12912 @item @code{omp_sched_dynamic}
12913 @item @code{omp_sched_guided}
12914 @item @code{omp_sched_auto}