stdio.h defines BUFSIZ

[unix-history] / usr / src / usr.bin / f77 / libF77 / pow_di.c

/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*
*      @(#)pow_di.c    5.3     %G%
*/

double
pow_di(ap, bp)
       double *ap;
       long *bp;
{
       register long n = *bp;
       double y, x = *ap;

       if (!n)
               return((double)1);
       if (n < 0) {
               x = (double)1 / x;
               n = -n;
       }
       while (!(n&1)) {
               x *= x;
               n >>= 1;
       }
       for (y = x; --n > 0; y *= x)
               while (!(n&1)) {
                       x *= x;
                       n >>= 1;
               }
       return(y);
}