1/* @(#)w_gamma.c 5.1 93/09/24 */
2/*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12
13/* double gamma(double x)
14 * Return the logarithm of the Gamma function of x or the Gamma function of x,
15 * depending on the library mode.
16 */
17
18#include <errno.h>
19#include <math.h>
20#include <math_private.h>
21#include <math-svid-compat.h>
22#include <libm-alias-double.h>
23
24#if LIBM_SVID_COMPAT
25double
26__tgamma(double x)
27{
28 int local_signgam;
29 double y = __ieee754_gamma_r(x,&local_signgam);
30
31 if(__glibc_unlikely (!isfinite (y) || y == 0)
32 && (isfinite (x) || (isinf (x) && x < 0.0))
33 && _LIB_VERSION != _IEEE_) {
34 if (x == 0.0)
35 return __kernel_standard(x,x,50); /* tgamma pole */
36 else if(floor(x)==x&&x<0.0)
37 return __kernel_standard(x,x,41); /* tgamma domain */
38 else if (y == 0)
39 __set_errno (ERANGE); /* tgamma underflow */
40 else
41 return __kernel_standard(x,x,40); /* tgamma overflow */
42 }
43 return local_signgam < 0 ? -y : y;
44}
45libm_alias_double (__tgamma, tgamma)
46#endif
47