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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
+}