libf2c/libF77/pow_ii.c

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