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54 lines
1.2 KiB
C
54 lines
1.2 KiB
C
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/* @(#)w_gamma.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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/* double gamma(double x)
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* Return the logarithm of the Gamma function of x or the Gamma function of x,
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* depending on the library mode.
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*/
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#include <math.h>
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#include <errno.h>
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#ifdef __STDC__
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double tgamma(double x)
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#else
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double tgamma(x)
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double x;
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#endif
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{
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double y;
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int local_signgam;
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y = gamma_r(x,&local_signgam);
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if (local_signgam < 0) y = -y;
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#ifdef _IEEE_LIBM
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return y;
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#else
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if(_LIB_VERSION == _IEEE_) return y;
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if(!finite(y)&&finite(x)) {
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if(floor(x)==x&&x<=0.0)
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{
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/* tgamma pole */
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errno = EDOM;
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return HUGE_VAL;
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}
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else
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{
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/* tgamma overflow */
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errno = ERANGE;
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return HUGE_VAL;
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}
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}
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return y;
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#endif
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}
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