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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

}