sysdeps/libm-ieee754/w_gamma.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 __gamma(double x)
  27 #else
  28         double __gamma(x)
  29         double x;
  30 #endif
  31 {
  32         double y;
  33 #ifndef _IEEE_LIBM
  34         if (_LIB_VERSION == _SVID_)
  35           {
  36             y = __ieee754_lgamma_r(x,&signgam);
  37
  38             if(!__finite(y)&&__finite(x)) {
  39               if(__floor(x)==x&&x<=(double)0.0)
  40                 /* lgamma pole */
  41                 return __kernel_standard(x,x,15);
  42               else
  43                 /* lgamma overflow */
  44                 return __kernel_standard(x,x,14);
  45             }
  46           }
  47         else
  48           {
  49 #endif
  50             int local_signgam;
  51             y = __ieee754_gamma_r(x,&local_signgam);
  52             if (local_signgam < 0) y = -y;
  53 #ifdef _IEEE_LIBM
  54             return y;
  55 #else
  56             if(_LIB_VERSION == _IEEE_) return y;
  57
  58             if(!__finite(y)&&__finite(x)) {
  59               if(__floor(x)==x&&x<=0.0)
  60                 return __kernel_standard(x,x,41); /* gamma pole */
  61               else
  62                 return __kernel_standard(x,x,40); /* gamma overflow */
  63             }
  64           }
  65         return y;
  66 #endif
  67 }
  68 weak_alias (__gamma, gamma)
  69 #ifdef NO_LONG_DOUBLE
  70 strong_alias (__gamma, __gammal)
  71 weak_alias (__gamma, gammal)
  72 #endif