118 lines
2.2 KiB
C
118 lines
2.2 KiB
C
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/* @(#)w_pow.c 5.2 93/10/01 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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FUNCTION
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<<pow>>, <<powf>>---x to the power y
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INDEX
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pow
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INDEX
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powf
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SYNOPSIS
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#include <math.h>
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double pow(double <[x]>, double <[y]>);
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float powf(float <[x]>, float <[y]>);
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DESCRIPTION
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<<pow>> and <<powf>> calculate <[x]> raised to the exponent <[y]>.
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@tex
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(That is, $x^y$.)
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@end tex
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RETURNS
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On success, <<pow>> and <<powf>> return the value calculated.
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When the argument values would produce overflow, <<pow>>
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returns <<HUGE_VAL>> and set <<errno>> to <<ERANGE>>. If the
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argument <[x]> passed to <<pow>> or <<powf>> is a negative
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noninteger, and <[y]> is also not an integer, then <<errno>>
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is set to <<EDOM>>. If <[x]> and <[y]> are both 0, then
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<<pow>> and <<powf>> return <<1>>.
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PORTABILITY
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<<pow>> is ANSI C. <<powf>> is an extension. */
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/*
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* wrapper pow(x,y) return x**y
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*/
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#include "fdlibm.h"
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#if __OBSOLETE_MATH
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#include <errno.h>
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#ifndef _DOUBLE_IS_32BITS
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#ifdef __STDC__
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double pow(double x, double y) /* wrapper pow */
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#else
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double pow(x,y) /* wrapper pow */
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double x,y;
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#endif
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{
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#ifdef _IEEE_LIBM
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return __ieee754_pow(x,y);
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#else
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double z;
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z=__ieee754_pow(x,y);
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if(_LIB_VERSION == _IEEE_|| isnan(y)) return z;
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if(x==0.0){
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if(y==0.0) {
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/* pow(0.0,0.0) */
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/* Not an error. */
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return 1.0;
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}
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if(finite(y)&&y<0.0) {
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/* 0**neg */
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errno = ERANGE;
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}
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return z;
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}
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if(!finite(z)) {
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if(finite(x)&&finite(y)) {
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if(isnan(z)) {
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/* neg**non-integral */
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errno = EDOM;
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} else {
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/* pow(x,y) overflow */
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errno = ERANGE;
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}
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return z;
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}
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}
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if(z==0.0&&finite(x)&&finite(y)) {
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/* pow(x,y) underflow */
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errno = ERANGE;
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}
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return z;
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#endif
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */
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#endif /* __OBSOLETE_MATH */
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