libf2c/libF77/pow_di.c

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