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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 |