lang/fortran/lib/libF77/pow_di.c

   1 #include "f2c.h"
   2
   3 double pow_di(ap, bp)
   4 doublereal *ap;
   5 integer *bp;
   6 {
   7 double pow, x;
   8 integer n;
   9
  10 pow = 1;
  11 x = *ap;
  12 n = *bp;
  13
  14 if(n != 0)
  15         {
  16         if(n < 0)
  17                 {
  18                 if(x == 0)
  19                         {
  20                         return(pow);
  21                         }
  22                 n = -n;
  23                 x = 1/x;
  24                 }
  25         for( ; ; )
  26                 {
  27                 if(n & 01)
  28                         pow *= x;
  29                 if(n >>= 1)
  30                         x *= x;
  31                 else
  32                         break;
  33                 }
  34         }
  35 return(pow);
  36 }