49 lines
1.1 KiB
C
49 lines
1.1 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 "fdlibm.h"
|
||
|
|
|
||
|
|
#ifndef _DOUBLE_IS_32BITS
|
||
|
|
|
||
|
|
#ifdef __STDC__
|
||
|
|
double tgamma(double x)
|
||
|
|
#else
|
||
|
|
double tgamma(x)
|
||
|
|
double x;
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
double y;
|
||
|
|
int local_signgam;
|
||
|
|
y = __ieee754_gamma_r(x,&local_signgam);
|
||
|
|
if (local_signgam < 0) y = -y;
|
||
|
|
#ifdef _IEEE_LIBM
|
||
|
|
return y;
|
||
|
|
#else
|
||
|
|
if(_LIB_VERSION == _IEEE_) return y;
|
||
|
|
|
||
|
|
if(!finite(y)&&finite(x)) {
|
||
|
|
if(floor(x)==x&&x<=0.0)
|
||
|
|
return __kernel_standard(x,x,41); /* tgamma pole */
|
||
|
|
else
|
||
|
|
return __kernel_standard(x,x,40); /* tgamma overflow */
|
||
|
|
}
|
||
|
|
return y;
|
||
|
|
#endif
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* defined(_DOUBLE_IS_32BITS) */
|