lib/libm/src/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 #include <sys/cdefs.h>
  14 #if defined(LIBM_SCCS) && !defined(lint)
  15 __RCSID("$NetBSD: w_gamma.c,v 1.11 2002/05/26 22:02:00 wiz Exp $");
  16 #endif
  17
  18 /* double gamma(double x)
  19  * Return the logarithm of the Gamma function of x.
  20  *
  21  * Method: call gamma_r
  22  */
  23
  24 #include "math.h"
  25 #include "math_private.h"
  26
  27 double
  28 gamma(double x)
  29 {
  30 #ifdef _IEEE_LIBM
  31         return __ieee754_lgamma_r(x,&signgam);
  32 #else
  33         double y;
  34         y = __ieee754_lgamma_r(x,&signgam);
  35         if(_LIB_VERSION == _IEEE_) return y;
  36         if(!finite(y)&&finite(x)) {
  37             if(floor(x)==x&&x<=0.0)
  38                 return __kernel_standard(x,x,41); /* gamma pole */
  39             else
  40                 return __kernel_standard(x,x,40); /* gamma overflow */
  41         } else
  42             return y;
  43 #endif
  44 }