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 | |
22 | double |
23 | __tgamma(double x) |
24 | { |
25 | int local_signgam; |
26 | double y = __ieee754_gamma_r(x,&local_signgam); |
27 | |
28 | if(__glibc_unlikely (!isfinite (y) || y == 0) |
29 | && (isfinite (x) || (isinf (x) && x < 0.0)) |
30 | && _LIB_VERSION != _IEEE_) { |
31 | if (x == 0.0) |
32 | return __kernel_standard(x,x,50); /* tgamma pole */ |
33 | else if(__floor(x)==x&&x<0.0) |
34 | return __kernel_standard(x,x,41); /* tgamma domain */ |
35 | else if (y == 0) |
36 | __set_errno (ERANGE); /* tgamma underflow */ |
37 | else |
38 | return __kernel_standard(x,x,40); /* tgamma overflow */ |
39 | } |
40 | return local_signgam < 0 ? -y : y; |
41 | } |
42 | weak_alias (__tgamma, tgamma) |
43 | #ifdef NO_LONG_DOUBLE |
44 | strong_alias (__tgamma, __tgammal) |
45 | weak_alias (__tgamma, tgammal) |
46 | #endif |
47 | |