1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- A D A . N U M E R I C S . F L O A T _ R A N D O M --
10 -- Copyright (C) 1992-1998 Free Software Foundation, Inc. --
12 -- This specification is derived from the Ada Reference Manual for use with --
13 -- GNAT. The copyright notice above, and the license provisions that follow --
14 -- apply solely to the contents of the part following the private keyword. --
16 -- GNAT is free software; you can redistribute it and/or modify it under --
17 -- terms of the GNU General Public License as published by the Free Soft- --
18 -- ware Foundation; either version 2, or (at your option) any later ver- --
19 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
20 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
21 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
22 -- for more details. You should have received a copy of the GNU General --
23 -- Public License distributed with GNAT; see file COPYING. If not, write --
24 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
25 -- MA 02111-1307, USA. --
27 -- As a special exception, if other files instantiate generics from this --
28 -- unit, or you link this unit with other files to produce an executable, --
29 -- this unit does not by itself cause the resulting executable to be --
30 -- covered by the GNU General Public License. This exception does not --
31 -- however invalidate any other reasons why the executable file might be --
32 -- covered by the GNU Public License. --
34 -- GNAT was originally developed by the GNAT team at New York University. --
35 -- Extensive contributions were provided by Ada Core Technologies Inc. --
37 ------------------------------------------------------------------------------
39 -- Note: the implementation used in this package was contributed by
40 -- Robert Eachus. It is based on the work of L. Blum, M. Blum, and
41 -- M. Shub, SIAM Journal of Computing, Vol 15. No 2, May 1986. The
42 -- particular choices for P and Q chosen here guarantee a period of
43 -- 562,085,314,430,582 (about 2**49), and the generated sequence has
44 -- excellent randomness properties. For further details, see the
45 -- paper "Fast Generation of Trustworthy Random Numbers", by Robert
46 -- Eachus, which describes both the algorithm and the efficient
47 -- implementation approach used here. This paper is available at
48 -- the Ada Core Technologies web site (http://www.gnat.com).
52 package Ada.Numerics.Float_Random is
56 type Generator is limited private;
58 subtype Uniformly_Distributed is Float range 0.0 .. 1.0;
60 function Random (Gen : Generator) return Uniformly_Distributed;
62 procedure Reset (Gen : Generator);
63 procedure Reset (Gen : Generator; Initiator : Integer);
65 -- Advanced facilities
67 type State is private;
69 procedure Save (Gen : Generator; To_State : out State);
70 procedure Reset (Gen : Generator; From_State : State);
72 Max_Image_Width : constant := 80;
74 function Image (Of_State : State) return String;
75 function Value (Coded_State : String) return State;
78 type Int is new Interfaces.Integer_32;
79 type Flt is digits 14;
81 K1 : constant := 94_833_359;
82 K1F : constant := 94_833_359.0;
83 K2 : constant := 47_416_679;
84 K2F : constant := 47_416_679.0;
85 Scal : constant := 1.0 / (K1F * K2F);
88 X1 : Int := 2999 ** 2; -- Square mod p
89 X2 : Int := 1439 ** 2; -- Square mod q
96 type Generator is limited record
100 end Ada.Numerics.Float_Random;