47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
/* @(#)w_gamma.c 5.1 93/09/24 */
|
|
/*
|
|
* ====================================================
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
|
*
|
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
|
* Permission to use, copy, modify, and distribute this
|
|
* software is freely granted, provided that this notice
|
|
* is preserved.
|
|
* ====================================================
|
|
*/
|
|
|
|
/* double gamma(double x)
|
|
* Return the logarithm of the Gamma function of x or the Gamma function of x,
|
|
* depending on the library mode.
|
|
*/
|
|
|
|
#include <errno.h>
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
|
|
double
|
|
__tgamma(double x)
|
|
{
|
|
int local_signgam;
|
|
double y = __ieee754_gamma_r(x,&local_signgam);
|
|
|
|
if(__glibc_unlikely (!__finite (y) || y == 0)
|
|
&& (__finite (x) || __isinf (x) < 0)
|
|
&& _LIB_VERSION != _IEEE_) {
|
|
if (x == 0.0)
|
|
return __kernel_standard(x,x,50); /* tgamma pole */
|
|
else if(__floor(x)==x&&x<0.0)
|
|
return __kernel_standard(x,x,41); /* tgamma domain */
|
|
else if (y == 0)
|
|
__set_errno (ERANGE); /* tgamma underflow */
|
|
else
|
|
return __kernel_standard(x,x,40); /* tgamma overflow */
|
|
}
|
|
return local_signgam < 0 ? -y : y;
|
|
}
|
|
weak_alias (__tgamma, tgamma)
|
|
#ifdef NO_LONG_DOUBLE
|
|
strong_alias (__tgamma, __tgammal)
|
|
weak_alias (__tgamma, tgammal)
|
|
#endif
|