libf2c/libF77/z_div.c

   1 #include "f2c.h"
   2
   3 #ifdef KR_headers
   4 extern VOID sig_die();
   5 VOID z_div(c, a, b) doublecomplex *a, *b, *c;
   6 #else
   7 extern void sig_die(char*, int);
   8 void z_div(doublecomplex *c, doublecomplex *a, doublecomplex *b)
   9 #endif
  10 {
  11         double ratio, den;
  12         double abr, abi, cr;
  13
  14         if( (abr = b->r) < 0.)
  15                 abr = - abr;
  16         if( (abi = b->i) < 0.)
  17                 abi = - abi;
  18         if( abr <= abi )
  19                 {
  20                 if(abi == 0) {
  21 #ifdef IEEE_COMPLEX_DIVIDE
  22                         if (a->i != 0 || a->r != 0)
  23                                 abi = 1.;
  24                         c->i = c->r = abi / abr;
  25                         return;
  26 #else
  27                         sig_die("complex division by zero", 1);
  28 #endif
  29                         }
  30                 ratio = b->r / b->i ;
  31                 den = b->i * (1 + ratio*ratio);
  32                 cr = (a->r*ratio + a->i) / den;
  33                 c->i = (a->i*ratio - a->r) / den;
  34                 }
  35
  36         else
  37                 {
  38                 ratio = b->i / b->r ;
  39                 den = b->r * (1 + ratio*ratio);
  40                 cr = (a->r + a->i*ratio) / den;
  41                 c->i = (a->i - a->r*ratio) / den;
  42                 }
  43         c->r = cr;
  44         }