math/w_lgamma.c

   1 /* @(#)w_lgamma.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 lgamma(double x)
  14  * Return the logarithm of the Gamma function of x.
  15  *
  16  * Method: call __ieee754_lgamma_r
  17  */
  18
  19 #include <math.h>
  20 #include <math_private.h>
  21
  22 double
  23 __lgamma(double x)
  24 {
  25         int local_signgam = 0;
  26         double y = __ieee754_lgamma_r(x,
  27                                       _LIB_VERSION != _ISOC_
  28                                       /* ISO C99 does not define the
  29                                          global variable.  */
  30                                       ? &signgam
  31                                       : &local_signgam);
  32         if(__builtin_expect(!__finite(y), 0)
  33            && __finite(x) && _LIB_VERSION != _IEEE_)
  34                 return __kernel_standard(x, x,
  35                                          __floor(x)==x&&x<=0.0
  36                                          ? 15 /* lgamma pole */
  37                                          : 14); /* lgamma overflow */
  38
  39         return y;
  40 }
  41 weak_alias (__lgamma, lgamma)
  42 strong_alias (__lgamma, __gamma)
  43 weak_alias (__gamma, gamma)
  44 #ifdef NO_LONG_DOUBLE
  45 strong_alias (__lgamma, __lgammal)
  46 weak_alias (__lgamma, lgammal)
  47 strong_alias (__gamma, __gammal)
  48 weak_alias (__gamma, gammal)
  49 #endif