109 lines
2.3 KiB
C
109 lines
2.3 KiB
C
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/* @(#)w_log10.c 5.1 93/09/24 */
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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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<<log10>>, <<log10f>>---base 10 logarithms
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INDEX
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log10
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INDEX
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log10f
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SYNOPSIS
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#include <math.h>
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double log10(double <[x]>);
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float log10f(float <[x]>);
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DESCRIPTION
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<<log10>> returns the base 10 logarithm of <[x]>.
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It is implemented as <<log(<[x]>) / log(10)>>.
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<<log10f>> is identical, save that it takes and returns <<float>> values.
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RETURNS
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<<log10>> and <<log10f>> return the calculated value.
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See the description of <<log>> for information on errors.
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PORTABILITY
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<<log10>> is ANSI C. <<log10f>> is an extension.
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*/
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/*
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* wrapper log10(X)
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*/
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#include "fdlibm.h"
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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 log10(double x) /* wrapper log10 */
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#else
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double log10(x) /* wrapper log10 */
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double x;
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#endif
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{
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#ifdef _IEEE_LIBM
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return __ieee754_log10(x);
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#else
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double z;
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struct exception exc;
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z = __ieee754_log10(x);
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if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
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if(x<=0.0) {
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#ifndef HUGE_VAL
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#define HUGE_VAL inf
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double inf = 0.0;
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SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */
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#endif
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exc.name = "log10";
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exc.err = 0;
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exc.arg1 = x;
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exc.arg2 = x;
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if (_LIB_VERSION == _SVID_)
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exc.retval = -HUGE;
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else
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exc.retval = -HUGE_VAL;
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if(x==0.0) {
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/* log10(0) */
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exc.type = SING;
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if (_LIB_VERSION == _POSIX_)
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errno = ERANGE;
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else if (!matherr(&exc)) {
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errno = ERANGE;
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}
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} else {
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/* log10(x<0) */
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exc.type = DOMAIN;
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if (_LIB_VERSION == _POSIX_)
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errno = EDOM;
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else if (!matherr(&exc)) {
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errno = EDOM;
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}
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exc.retval = nan("");
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}
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if (exc.err != 0)
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errno = exc.err;
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return exc.retval;
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} else
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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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