forked from KolibriOS/kolibrios
117 lines
2.4 KiB
C
117 lines
2.4 KiB
C
|
|
/* @(#)w_log10.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
|
|
<<log10>>, <<log10f>>---base 10 logarithms
|
|
|
|
INDEX
|
|
log10
|
|
INDEX
|
|
log10f
|
|
|
|
ANSI_SYNOPSIS
|
|
#include <math.h>
|
|
double log10(double <[x]>);
|
|
float log10f(float <[x]>);
|
|
|
|
TRAD_SYNOPSIS
|
|
#include <math.h>
|
|
double log10(<[x]>)
|
|
double <[x]>;
|
|
|
|
float log10f(<[x]>)
|
|
float <[x]>;
|
|
|
|
DESCRIPTION
|
|
<<log10>> returns the base 10 logarithm of <[x]>.
|
|
It is implemented as <<log(<[x]>) / log(10)>>.
|
|
|
|
<<log10f>> is identical, save that it takes and returns <<float>> values.
|
|
|
|
RETURNS
|
|
<<log10>> and <<log10f>> return the calculated value.
|
|
|
|
See the description of <<log>> for information on errors.
|
|
|
|
PORTABILITY
|
|
<<log10>> is ANSI C. <<log10f>> is an extension.
|
|
|
|
*/
|
|
|
|
/*
|
|
* wrapper log10(X)
|
|
*/
|
|
|
|
#include "fdlibm.h"
|
|
#include <errno.h>
|
|
|
|
#ifndef _DOUBLE_IS_32BITS
|
|
|
|
#ifdef __STDC__
|
|
double log10(double x) /* wrapper log10 */
|
|
#else
|
|
double log10(x) /* wrapper log10 */
|
|
double x;
|
|
#endif
|
|
{
|
|
#ifdef _IEEE_LIBM
|
|
return __ieee754_log10(x);
|
|
#else
|
|
double z;
|
|
struct exception exc;
|
|
z = __ieee754_log10(x);
|
|
if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
|
|
if(x<=0.0) {
|
|
#ifndef HUGE_VAL
|
|
#define HUGE_VAL inf
|
|
double inf = 0.0;
|
|
|
|
SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */
|
|
#endif
|
|
exc.name = "log10";
|
|
exc.err = 0;
|
|
exc.arg1 = x;
|
|
exc.arg2 = x;
|
|
if (_LIB_VERSION == _SVID_)
|
|
exc.retval = -HUGE;
|
|
else
|
|
exc.retval = -HUGE_VAL;
|
|
if(x==0.0) {
|
|
/* log10(0) */
|
|
exc.type = SING;
|
|
if (_LIB_VERSION == _POSIX_)
|
|
errno = ERANGE;
|
|
else if (!matherr(&exc)) {
|
|
errno = ERANGE;
|
|
}
|
|
} else {
|
|
/* log10(x<0) */
|
|
exc.type = DOMAIN;
|
|
if (_LIB_VERSION == _POSIX_)
|
|
errno = EDOM;
|
|
else if (!matherr(&exc)) {
|
|
errno = EDOM;
|
|
}
|
|
exc.retval = nan("");
|
|
}
|
|
if (exc.err != 0)
|
|
errno = exc.err;
|
|
return exc.retval;
|
|
} else
|
|
return z;
|
|
#endif
|
|
}
|
|
|
|
#endif /* defined(_DOUBLE_IS_32BITS) */
|