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90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
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/* @(#)w_lgamma.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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/* double lgamma(double x)
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* Return the logarithm of the Gamma function of x.
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*
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* Method: call __ieee754_lgamma_r
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*/
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#include "fdlibm.h"
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#include <reent.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 lgamma(double x)
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#else
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double lgamma(x)
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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_lgamma_r(x,&(_REENT_SIGNGAM(_REENT)));
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#else
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double y;
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struct exception exc;
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y = __ieee754_lgamma_r(x,&(_REENT_SIGNGAM(_REENT)));
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if(_LIB_VERSION == _IEEE_) return y;
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if(!finite(y)&&finite(x)) {
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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 = "lgamma";
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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(floor(x)==x&&x<=0.0) {
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/* lgamma(-integer) */
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exc.type = SING;
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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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} else {
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/* lgamma(finite) overflow */
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exc.type = OVERFLOW;
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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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}
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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 y;
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#endif
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */
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