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/* @(#)w_pow.c 5.2 93/10/01 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
FUNCTION
<<pow>>, <<powf>>---x to the power y
INDEX
pow
INDEX
powf
ANSI_SYNOPSIS
#include <math.h>
double pow(double <[x]>, double <[y]>);
float pow(float <[x]>, float <[y]>);
TRAD_SYNOPSIS
#include <math.h>
double pow(<[x]>, <[y]>);
double <[x]>, <[y]>;
float pow(<[x]>, <[y]>);
float <[x]>, <[y]>;
DESCRIPTION
<<pow>> and <<powf>> calculate <[x]> raised to the exp1.0nt <[y]>.
@tex
(That is, $x^y$.)
@end tex
RETURNS
On success, <<pow>> and <<powf>> return the value calculated.
When the argument values would produce overflow, <<pow>>
returns <<HUGE_VAL>> and set <<errno>> to <<ERANGE>>. If the
argument <[x]> passed to <<pow>> or <<powf>> is a negative
noninteger, and <[y]> is also not an integer, then <<errno>>
is set to <<EDOM>>. If <[x]> and <[y]> are both 0, then
<<pow>> and <<powf>> return <<1>>.
You can modify error handling for these functions using <<matherr>>.
PORTABILITY
<<pow>> is ANSI C. <<powf>> is an extension. */
/*
* wrapper pow(x,y) return x**y
*/
#include "fdlibm.h"
#include <errno.h>
#ifndef _DOUBLE_IS_32BITS
#ifdef __STDC__
double pow(double x, double y) /* wrapper pow */
#else
double pow(x,y) /* wrapper pow */
double x,y;
#endif
{
#ifdef _IEEE_LIBM
return __ieee754_pow(x,y);
#else
double z;
#ifndef HUGE_VAL
#define HUGE_VAL inf
double inf = 0.0;
SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */
#endif
struct exception exc;
z=__ieee754_pow(x,y);
if(_LIB_VERSION == _IEEE_|| isnan(y)) return z;
if(isnan(x)) {
if(y==0.0) {
/* pow(NaN,0.0) */
/* error only if _LIB_VERSION == _SVID_ & _XOPEN_ */
exc.type = DOMAIN;
exc.name = "pow";
exc.err = 0;
exc.arg1 = x;
exc.arg2 = y;
exc.retval = x;
if (_LIB_VERSION == _IEEE_ ||
_LIB_VERSION == _POSIX_) exc.retval = 1.0;
else if (!matherr(&exc)) {
errno = EDOM;
}
if (exc.err != 0)
errno = exc.err;
return exc.retval;
} else
return z;
}
if(x==0.0){
if(y==0.0) {
/* pow(0.0,0.0) */
/* error only if _LIB_VERSION == _SVID_ */
exc.type = DOMAIN;
exc.name = "pow";
exc.err = 0;
exc.arg1 = x;
exc.arg2 = y;
exc.retval = 0.0;
if (_LIB_VERSION != _SVID_) exc.retval = 1.0;
else if (!matherr(&exc)) {
errno = EDOM;
}
if (exc.err != 0)
errno = exc.err;
return exc.retval;
}
if(finite(y)&&y<0.0) {
/* 0**neg */
exc.type = DOMAIN;
exc.name = "pow";
exc.err = 0;
exc.arg1 = x;
exc.arg2 = y;
if (_LIB_VERSION == _SVID_)
exc.retval = 0.0;
else
exc.retval = -HUGE_VAL;
if (_LIB_VERSION == _POSIX_)
errno = EDOM;
else if (!matherr(&exc)) {
errno = EDOM;
}
if (exc.err != 0)
errno = exc.err;
return exc.retval;
}
return z;
}
if(!finite(z)) {
if(finite(x)&&finite(y)) {
if(isnan(z)) {
/* neg**non-integral */
exc.type = DOMAIN;
exc.name = "pow";
exc.err = 0;
exc.arg1 = x;
exc.arg2 = y;
if (_LIB_VERSION == _SVID_)
exc.retval = 0.0;
else
exc.retval = 0.0/0.0; /* X/Open allow NaN */
if (_LIB_VERSION == _POSIX_)
errno = EDOM;
else if (!matherr(&exc)) {
errno = EDOM;
}
if (exc.err != 0)
errno = exc.err;
return exc.retval;
} else {
/* pow(x,y) overflow */
exc.type = OVERFLOW;
exc.name = "pow";
exc.err = 0;
exc.arg1 = x;
exc.arg2 = y;
if (_LIB_VERSION == _SVID_) {
exc.retval = HUGE;
y *= 0.5;
if(x<0.0&&rint(y)!=y) exc.retval = -HUGE;
} else {
exc.retval = HUGE_VAL;
y *= 0.5;
if(x<0.0&&rint(y)!=y) exc.retval = -HUGE_VAL;
}
if (_LIB_VERSION == _POSIX_)
errno = ERANGE;
else if (!matherr(&exc)) {
errno = ERANGE;
}
if (exc.err != 0)
errno = exc.err;
return exc.retval;
}
}
}
if(z==0.0&&finite(x)&&finite(y)) {
/* pow(x,y) underflow */
exc.type = UNDERFLOW;
exc.name = "pow";
exc.err = 0;
exc.arg1 = x;
exc.arg2 = y;
exc.retval = 0.0;
if (_LIB_VERSION == _POSIX_)
errno = ERANGE;
else if (!matherr(&exc)) {
errno = ERANGE;
}
if (exc.err != 0)
errno = exc.err;
return exc.retval;
}
return z;
#endif
}
#endif /* defined(_DOUBLE_IS_32BITS) */
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