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/* Return quiet nan.
Copyright (C) 1997 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. */
/* XXX The ISO C 9X standard mentions a `n-char-sequence' which is provided
as the argument to this function but I have no clue what this means.
Perhaps it is a description of the bits set in the mantissa. */
#include <math.h>
#ifdef HANDLE_TAGP
# include <stdlib.h>
# include <string.h>
#else
# include <ieee754.h>
#endif
double
__nan (const char *tagp)
{
#ifdef HANDLE_TAGP
/* If we ever should have use of the TAGP parameter we will use the
strtod function to analyze it. */
char buf[6 + strlen (tagp)];
sprintf (buf, "NAN(%s)", tagp);
return strtod (buf, NULL);
#else
static const union ieee754_double nan_value =
{ ieee: { mantissa1: 0x1, mantissa0: 0x0, exponent: 0x7ff, negative: 0 } };
return nan_value.d;
#endif
}
weak_alias (__nan, nan)
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