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/* Copyright (C) 1991, 1992, 1995 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <math.h>
#include "ieee754.h"
/* Return nonzero if VALUE is not a number. */
int
DEFUN(__isnan, (value), double value)
{
union ieee754_double u;
u.d = value;
/* IEEE 754 NaN's have the maximum possible
exponent and a nonzero mantissa. */
return ((u.ieee.exponent & 0x7ff) == 0x7ff &&
(u.ieee.mantissa0 != 0 || u.ieee.mantissa1 != 0));
}
weak_alias (__isnan, isnan)
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