newlib/libm/math/wf_pow.c

   1 /* wf_pow.c -- float version of w_pow.c.
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 /*
  17  * wrapper powf(x,y) return x**y
  18  */
  19
  20 #include "fdlibm.h"
  21 #include <errno.h>
  22
  23 #ifdef __STDC__
  24         float powf(float x, float y)    /* wrapper powf */
  25 #else
  26         float powf(x,y)                 /* wrapper powf */
  27         float x,y;
  28 #endif
  29 {
  30 #ifdef _IEEE_LIBM
  31         return  __ieee754_powf(x,y);
  32 #else
  33         float z;
  34         struct exception exc;
  35         z=__ieee754_powf(x,y);
  36         if(_LIB_VERSION == _IEEE_|| isnanf(y)) return z;
  37         if(isnanf(x)) {
  38             if(y==(float)0.0) {
  39                 /* powf(NaN,0.0) */
  40                 /* error only if _LIB_VERSION == _SVID_ & _XOPEN_ */
  41                 exc.type = DOMAIN;
  42                 exc.name = "powf";
  43                 exc.err = 0;
  44                 exc.arg1 = (double)x;
  45                 exc.arg2 = (double)y;
  46                 exc.retval = 1.0;
  47                 if (_LIB_VERSION == _IEEE_ ||
  48                     _LIB_VERSION == _POSIX_) exc.retval = 1.0;
  49                 else if (!matherr(&exc)) {
  50                         errno = EDOM;
  51                 }
  52                 if (exc.err != 0)
  53                    errno = exc.err;
  54                 return (float)exc.retval;
  55             } else
  56                 return z;
  57         }
  58         if(x==(float)0.0){
  59             if(y==(float)0.0) {
  60                 /* powf(0.0,0.0) */
  61                 /* error only if _LIB_VERSION == _SVID_ */
  62                 exc.type = DOMAIN;
  63                 exc.name = "powf";
  64                 exc.err = 0;
  65                 exc.arg1 = (double)x;
  66                 exc.arg2 = (double)y;
  67                 exc.retval = 0.0;
  68                 if (_LIB_VERSION != _SVID_) exc.retval = 1.0;
  69                 else if (!matherr(&exc)) {
  70                         errno = EDOM;
  71                 }
  72                 if (exc.err != 0)
  73                    errno = exc.err;
  74                 return (float)exc.retval;
  75             }
  76             if(finitef(y)&&y<(float)0.0) {
  77                 /* 0**neg */
  78                 exc.type = DOMAIN;
  79                 exc.name = "powf";
  80                 exc.err = 0;
  81                 exc.arg1 = (double)x;
  82                 exc.arg2 = (double)y;
  83                 if (_LIB_VERSION == _SVID_)
  84                   exc.retval = 0.0;
  85                 else
  86                   exc.retval = -HUGE_VAL;
  87                 if (_LIB_VERSION == _POSIX_)
  88                   errno = EDOM;
  89                 else if (!matherr(&exc)) {
  90                   errno = EDOM;
  91                 }
  92                 if (exc.err != 0)
  93                    errno = exc.err;
  94                 return (float)exc.retval;
  95             }
  96             return z;
  97         }
  98         if(!finitef(z)) {
  99             if(finitef(x)&&finitef(y)) {
 100                 if(isnanf(z)) {
 101                     /* neg**non-integral */
 102                     exc.type = DOMAIN;
 103                     exc.name = "powf";
 104                     exc.err = 0;
 105                     exc.arg1 = (double)x;
 106                     exc.arg2 = (double)y;
 107                     if (_LIB_VERSION == _SVID_)
 108                         exc.retval = 0.0;
 109                     else
 110                         exc.retval = 0.0/0.0;   /* X/Open allow NaN */
 111                     if (_LIB_VERSION == _POSIX_)
 112                         errno = EDOM;
 113                     else if (!matherr(&exc)) {
 114                         errno = EDOM;
 115                     }
 116                     if (exc.err != 0)
 117                         errno = exc.err;
 118                     return (float)exc.retval;
 119                 } else {
 120                     /* powf(x,y) overflow */
 121                     exc.type = OVERFLOW;
 122                     exc.name = "powf";
 123                     exc.err = 0;
 124                     exc.arg1 = (double)x;
 125                     exc.arg2 = (double)y;
 126                     if (_LIB_VERSION == _SVID_) {
 127                        exc.retval = HUGE;
 128                        y *= 0.5;
 129                        if(x<0.0&&rint(y)!=y) exc.retval = -HUGE;
 130                     } else {
 131                        exc.retval = HUGE_VAL;
 132                        y *= 0.5;
 133                        if(x<0.0&&rint(y)!=y) exc.retval = -HUGE_VAL;
 134                     }
 135                     if (_LIB_VERSION == _POSIX_)
 136                         errno = ERANGE;
 137                     else if (!matherr(&exc)) {
 138                         errno = ERANGE;
 139                     }
 140                     if (exc.err != 0)
 141                         errno = exc.err;
 142                     return (float)exc.retval;
 143                 }
 144             }
 145         }
 146         if(z==(float)0.0&&finitef(x)&&finitef(y)) {
 147             /* powf(x,y) underflow */
 148             exc.type = UNDERFLOW;
 149             exc.name = "powf";
 150             exc.err = 0;
 151             exc.arg1 = (double)x;
 152             exc.arg2 = (double)y;
 153             exc.retval =  0.0;
 154             if (_LIB_VERSION == _POSIX_)
 155                 errno = ERANGE;
 156             else if (!matherr(&exc)) {
 157                 errno = ERANGE;
 158             }
 159             if (exc.err != 0)
 160                 errno = exc.err;
 161             return (float)exc.retval;
 162         }
 163         return z;
 164 #endif
 165 }
 166
 167 #ifdef _DOUBLE_IS_32BITS
 168
 169 #ifdef __STDC__
 170         double pow(double x, double y)
 171 #else
 172         double pow(x,y)
 173         double x,y;
 174 #endif
 175 {
 176         return (double) powf((float) x, (float) y);
 177 }
 178
 179 #endif /* defined(_DOUBLE_IS_32BITS) */