math/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 /*
  16  * wrapper pow(x,y) return x**y
  17  */
  18
  19 #include <math.h>
  20 #include "math_private.h"
  21
  22
  23 #ifdef __STDC__
  24         double __pow(double x, double y)        /* wrapper pow */
  25 #else
  26         double __pow(x,y)                       /* wrapper pow */
  27         double x,y;
  28 #endif
  29 {
  30 #ifdef _IEEE_LIBM
  31         return  __ieee754_pow(x,y);
  32 #else
  33         double z;
  34         z=__ieee754_pow(x,y);
  35         if(_LIB_VERSION == _IEEE_|| __isnan(y)) return z;
  36         if(__isnan(x)) {
  37             if(y==0.0)
  38                 return __kernel_standard(x,y,42); /* pow(NaN,0.0) */
  39             else
  40                 return z;
  41         }
  42         if(x==0.0) {
  43             if(y==0.0)
  44                 return __kernel_standard(x,y,20); /* pow(0.0,0.0) */
  45             if(__finite(y)&&y<0.0) {
  46               if (signbit (x) && signbit (z))
  47                 return __kernel_standard(x,y,23); /* pow(-0.0,negative) */
  48               else
  49                 return __kernel_standard(x,y,43); /* pow(+0.0,negative) */
  50             }
  51             return z;
  52         }
  53         if(!__finite(z)) {
  54             if(__finite(x)&&__finite(y)) {
  55                 if(__isnan(z))
  56                     return __kernel_standard(x,y,24); /* pow neg**non-int */
  57                 else
  58                     return __kernel_standard(x,y,21); /* pow overflow */
  59             }
  60         }
  61         if(z==0.0&&__finite(x)&&__finite(y))
  62             return __kernel_standard(x,y,22); /* pow underflow */
  63         return z;
  64 #endif
  65 }
  66 weak_alias (__pow, pow)
  67 #ifdef NO_LONG_DOUBLE
  68 strong_alias (__pow, __powl)
  69 weak_alias (__pow, powl)
  70 #endif