libf2c/libF77/c_div.c

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