math/w_tgamma.c

   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 #if defined(LIBM_SCCS) && !defined(lint)
  14 static char rcsid[] = "$NetBSD: w_gamma.c,v 1.7 1995/11/20 22:06:43 jtc Exp $";
  15 #endif
  16
  17 /* double gamma(double x)
  18  * Return  the logarithm of the Gamma function of x or the Gamma function of x,
  19  * depending on the library mode.
  20  */
  21
  22 #include <math.h>
  23 #include "math_private.h"
  24
  25 #ifdef __STDC__
  26         double __tgamma(double x)
  27 #else
  28         double __tgamma(x)
  29         double x;
  30 #endif
  31 {
  32         double y;
  33         int local_signgam;
  34         y = __ieee754_gamma_r(x,&local_signgam);
  35         if (local_signgam < 0) y = -y;
  36 #ifdef _IEEE_LIBM
  37         return y;
  38 #else
  39         if(_LIB_VERSION == _IEEE_) return y;
  40
  41         if(!__finite(y)&&__finite(x)) {
  42           if (x == 0.0)
  43             return __kernel_standard(x,x,50); /* tgamma pole */
  44           else if(__floor(x)==x&&x<0.0)
  45             return __kernel_standard(x,x,41); /* tgamma domain */
  46           else
  47             return __kernel_standard(x,x,40); /* tgamma overflow */
  48         }
  49         return y;
  50 #endif
  51 }
  52 weak_alias (__tgamma, tgamma)
  53 #ifdef NO_LONG_DOUBLE
  54 strong_alias (__tgamma, __tgammal)
  55 weak_alias (__tgamma, tgammal)
  56 #endif