libf2c/libF77/pow_di.c

   1 #include "f2c.h"
   2
   3 double
   4 pow_di (doublereal * ap, integer * bp)
   5 {
   6   double pow, x;
   7   integer n;
   8   unsigned long u;
   9
  10   pow = 1;
  11   x = *ap;
  12   n = *bp;
  13
  14   if (n != 0)
  15     {
  16       if (n < 0)
  17         {
  18           n = -n;
  19           x = 1 / x;
  20         }
  21       for (u = n;;)
  22         {
  23           if (u & 01)
  24             pow *= x;
  25           if (u >>= 1)
  26             x *= x;
  27           else
  28             break;
  29         }
  30     }
  31   return (pow);
  32 }