lib/libm/src/w_pow.c

   1
   2
   3 /* @(#)w_pow.c 5.2 93/10/01 */
   4 /*
   5  * ====================================================
   6  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   7  *
   8  * Developed at SunPro, a Sun Microsystems, Inc. business.
   9  * Permission to use, copy, modify, and distribute this
  10  * software is freely granted, provided that this notice
  11  * is preserved.
  12  * ====================================================
  13  */
  14
  15 #include <sys/cdefs.h>
  16 #if defined(LIBM_SCCS) && !defined(lint)
  17 __RCSID("$NetBSD: w_pow.c,v 1.7 2002/05/26 22:02:02 wiz Exp $");
  18 #endif
  19
  20 /*
  21  * wrapper pow(x,y) return x**y
  22  */
  23
  24 #include "math.h"
  25 #include "math_private.h"
  26
  27
  28 double
  29 pow(double x, double y) /* wrapper pow */
  30 {
  31 #ifdef _IEEE_LIBM
  32         return  __ieee754_pow(x,y);
  33 #else
  34         double z;
  35         z=__ieee754_pow(x,y);
  36         if(_LIB_VERSION == _IEEE_|| isnan(y)) return z;
  37         if(isnan(x)) {
  38             if(y==0.0)
  39                 return __kernel_standard(x,y,42); /* pow(NaN,0.0) */
  40             else
  41                 return z;
  42         }
  43         if(x==0.0){
  44             if(y==0.0)
  45                 return __kernel_standard(x,y,20); /* pow(0.0,0.0) */
  46             if(finite(y)&&y<0.0)
  47                 return __kernel_standard(x,y,23); /* pow(0.0,negative) */
  48             return z;
  49         }
  50         if(!finite(z)) {
  51             if(finite(x)&&finite(y)) {
  52                 if(isnan(z))
  53                     return __kernel_standard(x,y,24); /* pow neg**non-int */
  54                 else
  55                     return __kernel_standard(x,y,21); /* pow overflow */
  56             }
  57         }
  58         if(z==0.0&&finite(x)&&finite(y))
  59             return __kernel_standard(x,y,22); /* pow underflow */
  60         return z;
  61 #endif
  62 }