math/w_tgamma_template.c

   1 /* Wrapper to set errno for tgamma.
   2    Copyright (C) 2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 /* Only build wrappers from the templates for the types that define the macro
  20    below.  This macro is set in math-type-macros-<type>.h in sysdeps/generic
  21    for each floating-point type.  */
  22 #if __USE_WRAPPER_TEMPLATE
  23
  24 # include <fenv.h>
  25 # include <math.h>
  26 # include <math_private.h>
  27
  28 #define M_CALL_FUNC_X(x) x ## _r
  29 #define M_CALL_FUNC(x) M_CALL_FUNC_X (x)
  30
  31 FLOAT
  32 M_DECL_FUNC (__tgamma) (FLOAT x)
  33 {
  34   int local_signgam;
  35   FLOAT y = M_CALL_FUNC (M_SUF (__ieee754_gamma)) (x, &local_signgam);
  36
  37   if (__glibc_unlikely (!isfinite (y) || y == 0)
  38       && (isfinite (x) || (isinf (x) && x < 0)))
  39     {
  40       if (x == 0)
  41         /* Pole error: tgamma(x=0).  */
  42         __set_errno (ERANGE);
  43       else if (M_SUF (__floor) (x) == x && x < 0)
  44         /* Domain error: tgamma(integer x<0).  */
  45         __set_errno (EDOM);
  46       else
  47         /* Overflow or underflow.  */
  48         __set_errno (ERANGE);
  49     }
  50   return local_signgam < 0 ? -y : y;
  51 }
  52 declare_mgen_alias (__tgamma, tgamma)
  53
  54 #endif /* __USE_WRAPPER_TEMPLATE.  */