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70317d8506
* libm/mathfp/s_logarithm.c: Fix error introduced by previous
fix when handling negative input values. Make function
consistent with math directory and glibc version such that
inf and nan values return inf and nan respectively with no
errno setting.
* libm/mathfp/sf_logarithm.c: Ditto.
* libm/math/w_log.c: Set errno to ERANGE when input is 0.0.
* libm/math/wf_log.c: Ditto.
* libm/math/w_log10.c: Ditto.
* libm/math/wf_log10.c: Ditto.
117 lines
2.5 KiB
C
117 lines
2.5 KiB
C
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/* @(#)w_log.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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<<log>>, <<logf>>---natural logarithms
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INDEX
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log
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INDEX
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logf
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ANSI_SYNOPSIS
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#include <math.h>
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double log(double <[x]>);
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float logf(float <[x]>);
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TRAD_SYNOPSIS
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#include <math.h>
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double log(<[x]>);
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double <[x]>;
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float logf(<[x]>);
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float <[x]>;
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DESCRIPTION
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Return the natural logarithm of <[x]>, that is, its logarithm base e
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(where e is the base of the natural system of logarithms, 2.71828@dots{}).
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<<log>> and <<logf>> are identical save for the return and argument types.
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You can use the (non-ANSI) function <<matherr>> to specify error
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handling for these functions.
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RETURNS
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Normally, returns the calculated value. When <[x]> is zero, the
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returned value is <<-HUGE_VAL>> and <<errno>> is set to <<ERANGE>>.
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When <[x]> is negative, the returned value is NaN (not a number) and
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<<errno>> is set to <<EDOM>>. You can control the error behavior via
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<<matherr>>.
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PORTABILITY
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<<log>> is ANSI. <<logf>> is an extension.
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*/
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/*
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* wrapper log(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 log(double x) /* wrapper log */
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#else
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double log(x) /* wrapper log */
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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_log(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_log(x);
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if(_LIB_VERSION == _IEEE_ || isnan(x) || x > 0.0) return z;
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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 = "log";
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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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/* log(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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/* log(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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#endif
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */
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