www.pudn.com > 文件恢复及修补 C 语言源程序.zip > POW.C

 
/*********************************************************** 
 *               The TULSA IBM C BOARD                     * 
 *                   918-664-8737                          * 
 *             300/1200 XMODEM, 24 Hours                   * 
 **********************************************************/ 
 
#include "math.h" 
#include "errno.h" 
 
double pow(a,b) 
double a,b; 
{ 
        double loga; 
        extern int errno; 
 
        if (a<=0.0) { 
                if (a<0.0 || a==0.0 && b<=0.0) { 
                        errno = EDOM; 
                        return -HUGE; 
                } 
                else return 0.0; 
        } 
        loga = log(a); 
        loga *= b; 
        if (loga > LOGHUGE) { 
                errno = ERANGE; 
                return HUGE; 
        } 
        if (loga < LOGTINY) { 
                errno = ERANGE; 
                return 0.0; 
        } 
        return exp(loga); 
}