diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/e_gamma_r.c')
-rw-r--r-- | sysdeps/ieee754/dbl-64/e_gamma_r.c | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/e_gamma_r.c b/sysdeps/ieee754/dbl-64/e_gamma_r.c new file mode 100644 index 0000000..bd802c2 --- /dev/null +++ b/sysdeps/ieee754/dbl-64/e_gamma_r.c @@ -0,0 +1,51 @@ +/* Implementation of gamma function according to ISO C. + Copyright (C) 1997, 1999 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <math.h> +#include <math_private.h> + + +double +__ieee754_gamma_r (double x, int *signgamp) +{ + /* We don't have a real gamma implementation now. We'll use lgamma + and the exp function. But due to the required boundary + conditions we must check some values separately. */ + int32_t hx; + u_int32_t lx; + + EXTRACT_WORDS (hx, lx, x); + + if (((hx & 0x7fffffff) | lx) == 0) + { + /* Return value for x == 0 is NaN with invalid exception. */ + *signgamp = 0; + return x / x; + } + if (hx < 0 && (u_int32_t) hx < 0xfff00000 && __rint (x) == x) + { + /* Return value for integer x < 0 is NaN with invalid exception. */ + *signgamp = 0; + return (x - x) / (x - x); + } + + /* XXX FIXME. */ + return __ieee754_exp (__ieee754_lgamma_r (x, signgamp)); +} |