BSD 4_1c_2 release

[unix-history] / usr / src / usr.lib / libm / pow.c

/*      @(#)pow.c       4.1     12/25/82        */

/*
       computes a^b.
       uses log and exp
*/

#include        <errno.h>
int errno;
double log(), exp();

double
pow(arg1,arg2)
double arg1, arg2;
{
       double temp;
       long l;

       asm("   bispsw  $0xe0");
       if(arg1 <= 0.) {
               if(arg1 == 0.) {
                       if(arg2 <= 0.)
                               goto domain;
                       return(0.);
               }
               l = arg2;
               if(l != arg2)
                       goto domain;
               temp = exp(arg2 * log(-arg1));
               if(l & 1)
                       temp = -temp;
               return(temp);
       }
       return(exp(arg2 * log(arg1)));

domain:
       errno = EDOM;
       return(0.);
}