0,0 → 1,231 |
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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. |
* ==================================================== |
*/ |
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/* |
FUNCTION |
<<pow>>, <<powf>>---x to the power y |
INDEX |
pow |
INDEX |
powf |
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ANSI_SYNOPSIS |
#include <math.h> |
double pow(double <[x]>, double <[y]>); |
float powf(float <[x]>, float <[y]>); |
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TRAD_SYNOPSIS |
#include <math.h> |
double pow(<[x]>, <[y]>); |
double <[x]>, <[y]>; |
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float powf(<[x]>, <[y]>); |
float <[x]>, <[y]>; |
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DESCRIPTION |
<<pow>> and <<powf>> calculate <[x]> raised to the exponent <[y]>. |
@tex |
(That is, $x^y$.) |
@end tex |
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RETURNS |
On success, <<pow>> and <<powf>> return the value calculated. |
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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>>. |
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You can modify error handling for these functions using <<matherr>>. |
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PORTABILITY |
<<pow>> is ANSI C. <<powf>> is an extension. */ |
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/* |
* wrapper pow(x,y) return x**y |
*/ |
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#include "fdlibm.h" |
#include <errno.h> |
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#ifndef _DOUBLE_IS_32BITS |
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#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; |
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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 = 1.0; |
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 |
} |
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#endif /* defined(_DOUBLE_IS_32BITS) */ |
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