47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
/* @(#)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 <errno.h>
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#include <math.h>
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#include <math_private.h>
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#include <math-svid-compat.h>
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#include <libm-alias-double.h>
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#if LIBM_SVID_COMPAT
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double
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__tgamma(double x)
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{
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int local_signgam;
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double y = __ieee754_gamma_r(x,&local_signgam);
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if(__glibc_unlikely (!isfinite (y) || y == 0)
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&& (isfinite (x) || (isinf (x) && x < 0.0))
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&& _LIB_VERSION != _IEEE_) {
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if (x == 0.0)
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return __kernel_standard(x,x,50); /* tgamma pole */
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else if(floor(x)==x&&x<0.0)
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return __kernel_standard(x,x,41); /* tgamma domain */
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else if (y == 0)
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__set_errno (ERANGE); /* tgamma underflow */
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else
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return __kernel_standard(x,x,40); /* tgamma overflow */
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}
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return local_signgam < 0 ? -y : y;
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}
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libm_alias_double (__tgamma, tgamma)
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#endif
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