freebsd-dev/lib/libF77/pow_di.c

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#include "f2c.h"
#ifdef KR_headers
double pow_di(ap, bp) doublereal *ap; integer *bp;
#else
double pow_di(doublereal *ap, integer *bp)
#endif
{
double pow, x;
integer n;
unsigned long u;
pow = 1;
x = *ap;
n = *bp;
if(n != 0)
{
if(n < 0)
{
n = -n;
x = 1/x;
}
for(u = n; ; )
{
if(u & 01)
pow *= x;
if(u >>= 1)
x *= x;
else
break;
}
}
return(pow);
}