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[glibc/history.git] / math / s_nan.c
blob9b2c50558bf39e16687d677d55e7b19c404e8c9d
1 /* Return quiet nan.
2 Copyright (C) 1997 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19 02111-1307 USA. */
21 #include <math.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <ieee754.h>
28 double
29 __nan (const char *tagp)
31 if (tagp[0] != '\0')
33 char buf[6 + strlen (tagp)];
34 sprintf (buf, "NAN(%s)", tagp);
35 return strtod (buf, NULL);
38 return NAN;
40 weak_alias (__nan, nan)
41 #ifdef NO_LONG_DOUBLE
42 strong_alias (__nan, __nanl)
43 weak_alias (__nan, nanl)
44 #endif