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/* @(#)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 <math.h>
#include <errno.h>
#ifdef __STDC__
double tgamma(double x)
#else
double tgamma(x)
double x;
#endif
{
double y;
int local_signgam;
y = 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)
{
/* tgamma pole */
errno = EDOM;
return HUGE_VAL;
}
else
{
/* tgamma overflow */
errno = ERANGE;
return HUGE_VAL;
}
}
return y;
#endif
}
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