| 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 | |
|---|
