pow_ri.c

DTMK软件开发包,此为开源软件,是一款很好的医学图像开发资源.

#include "v3p_f2c.h"
#ifdef __cplusplus
extern "C" {
#endif

#ifdef KR_headers
double pow_ri(ap, bp) real *ap; integer *bp;
#else
double pow_ri(real *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);
}
#ifdef __cplusplus
}
#endif