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 |
25 | double |
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 | } |
45 | libm_alias_double (__tgamma, tgamma) |
46 | #endif |
47 | |