toolchain/gcc/newlib/libm/mathfp/s_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 /* double gamma(double x)
  14  * Return  the logarithm of the Gamma function of x or the Gamma function of x,
  15  * depending on the library mode.
  16  */
  17
  18 #include <math.h>
  19 #include <errno.h>
  20
  21 #ifdef __STDC__
  22         double tgamma(double x)
  23 #else
  24         double tgamma(x)
  25         double x;
  26 #endif
  27 {
  28         double y;
  29         int local_signgam;
  30         y = gamma_r(x,&local_signgam);
  31         if (local_signgam < 0) y = -y;
  32 #ifdef _IEEE_LIBM
  33         return y;
  34 #else
  35         if(_LIB_VERSION == _IEEE_) return y;
  36
  37         if(!finite(y)&&finite(x)) {
  38           if(floor(x)==x&&x<=0.0)
  39             {
  40               /* tgamma pole */
  41               errno = EDOM;
  42               return HUGE_VAL;
  43             }
  44           else
  45             {
  46               /* tgamma overflow */
  47               errno = ERANGE;
  48               return HUGE_VAL;
  49             }
  50         }
  51         return y;
  52 #endif
  53 }