mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-23 05:20:06 +00:00
3bde1a69c1
* sysdeps/ieee754/ldbl-96/e_lgammal_r.c: New file. Contributed by Stephen L. Moshier <moshier@na-net.ornl.gov>. * sysdeps/ieee754/ldbl-96/e_gammal_r.c: Fix handling of boundary cases. * sysdeps/ieee754/dbl-64/e_gamma_r.c: Always initialize sign variable. * sysdeps/ieee754/flt-32/e_gammaf_r.c: Likewise. * sysdeps/i386/fpu/libm-test-ulps: Adjust after addition of lgammal.
58 lines
1.9 KiB
C
58 lines
1.9 KiB
C
/* Implementation of gamma function according to ISO C.
|
|
Copyright (C) 1997, 1999, 2001 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);
|
|
}
|
|
if ((unsigned int) hx == 0xfff00000 && lx==0)
|
|
{
|
|
/* x == -Inf. According to ISO this is NaN. */
|
|
*signgamp = 0;
|
|
return x - x;
|
|
}
|
|
|
|
/* XXX FIXME. */
|
|
return __ieee754_exp (__ieee754_lgamma_r (x, signgamp));
|
|
}
|