mirror of
https://github.com/KolibriOS/kolibrios.git
synced 2024-12-16 03:42:35 +03:00
137 lines
2.8 KiB
C
137 lines
2.8 KiB
C
|
|
/* @(#)w_exp.c 5.1 93/09/24 */
|
|
/*
|
|
* ====================================================
|
|
* 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
|
|
<<exp>>, <<expf>>---exponential
|
|
INDEX
|
|
exp
|
|
INDEX
|
|
expf
|
|
|
|
ANSI_SYNOPSIS
|
|
#include <math.h>
|
|
double exp(double <[x]>);
|
|
float expf(float <[x]>);
|
|
|
|
TRAD_SYNOPSIS
|
|
#include <math.h>
|
|
double exp(<[x]>);
|
|
double <[x]>;
|
|
|
|
float expf(<[x]>);
|
|
float <[x]>;
|
|
|
|
DESCRIPTION
|
|
<<exp>> and <<expf>> calculate the exponential of <[x]>, that is,
|
|
@ifnottex
|
|
e raised to the power <[x]> (where e
|
|
@end ifnottex
|
|
@tex
|
|
$e^x$ (where $e$
|
|
@end tex
|
|
is the base of the natural system of logarithms, approximately 2.71828).
|
|
|
|
You can use the (non-ANSI) function <<matherr>> to specify
|
|
error handling for these functions.
|
|
|
|
RETURNS
|
|
On success, <<exp>> and <<expf>> return the calculated value.
|
|
If the result underflows, the returned value is <<0>>. If the
|
|
result overflows, the returned value is <<HUGE_VAL>>. In
|
|
either case, <<errno>> is set to <<ERANGE>>.
|
|
|
|
PORTABILITY
|
|
<<exp>> is ANSI C. <<expf>> is an extension.
|
|
|
|
*/
|
|
|
|
/*
|
|
* wrapper exp(x)
|
|
*/
|
|
|
|
#include "fdlibm.h"
|
|
#include <errno.h>
|
|
|
|
#ifndef _DOUBLE_IS_32BITS
|
|
|
|
#ifdef __STDC__
|
|
static const double
|
|
#else
|
|
static double
|
|
#endif
|
|
o_threshold= 7.09782712893383973096e+02, /* 0x40862E42, 0xFEFA39EF */
|
|
u_threshold= -7.45133219101941108420e+02; /* 0xc0874910, 0xD52D3051 */
|
|
|
|
#ifdef __STDC__
|
|
double exp(double x) /* wrapper exp */
|
|
#else
|
|
double exp(x) /* wrapper exp */
|
|
double x;
|
|
#endif
|
|
{
|
|
#ifdef _IEEE_LIBM
|
|
return __ieee754_exp(x);
|
|
#else
|
|
double z;
|
|
struct exception exc;
|
|
z = __ieee754_exp(x);
|
|
if(_LIB_VERSION == _IEEE_) return z;
|
|
if(finite(x)) {
|
|
if(x>o_threshold) {
|
|
/* exp(finite) overflow */
|
|
#ifndef HUGE_VAL
|
|
#define HUGE_VAL inf
|
|
double inf = 0.0;
|
|
|
|
SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */
|
|
#endif
|
|
exc.type = OVERFLOW;
|
|
exc.name = "exp";
|
|
exc.err = 0;
|
|
exc.arg1 = exc.arg2 = x;
|
|
if (_LIB_VERSION == _SVID_)
|
|
exc.retval = HUGE;
|
|
else
|
|
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;
|
|
} else if(x<u_threshold) {
|
|
/* exp(finite) underflow */
|
|
exc.type = UNDERFLOW;
|
|
exc.name = "exp";
|
|
exc.err = 0;
|
|
exc.arg1 = exc.arg2 = x;
|
|
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) */
|