/* Implementation of gamma function according to ISO C.
Copyright (C) 1997, 1999, 2001, 2003, 2004 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper , 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include
#include
long double
__ieee754_gammal_r (long 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. */
u_int32_t es, hx, lx;
GET_LDOUBLE_WORDS (es, hx, lx, x);
if (((es & 0x7fff) | hx | lx) == 0)
{
/* Return value for x == 0 is Inf with divide by zero exception. */
*signgamp = 0;
return 1.0 / x;
}
if (es == 0xffffffff && ((hx & 0x7fffffff) | lx) == 0)
{
/* x == -Inf. According to ISO this is NaN. */
*signgamp = 0;
return x - x;
}
if ((es & 0x7fff) == 0x7fff && ((hx & 0x7fffffff) | lx) != 0)
{
/* NaN, return it. */
*signgamp = 0;
return x;
}
if ((es & 0x8000) != 0 && x < 0xffffffff && __rintl (x) == x)
{
/* Return value for integer x < 0 is NaN with invalid exception. */
*signgamp = 0;
return (x - x) / (x - x);
}
/* XXX FIXME. */
return __ieee754_expl (__ieee754_lgammal_r (x, signgamp));
}