toolchain/gcc/newlib/libm/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 /* 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 "fdlibm.h"
  19
  20 #ifdef __STDC__
  21         double tgamma(double x)
  22 #else
  23         double tgamma(x)
  24         double x;
  25 #endif
  26 {
  27         double y;
  28         int local_signgam;
  29         y = __ieee754_gamma_r(x,&local_signgam);
  30         if (local_signgam < 0) y = -y;
  31 #ifdef _IEEE_LIBM
  32         return y;
  33 #else
  34         if(_LIB_VERSION == _IEEE_) return y;
  35
  36         if(!finite(y)&&finite(x)) {
  37           if(floor(x)==x&&x<=0.0)
  38             return __kernel_standard(x,x,41); /* tgamma pole */
  39           else
  40             return __kernel_standard(x,x,40); /* tgamma overflow */
  41         }
  42         return y;
  43 #endif
  44 }