1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
4 .\" Distributed under GPL
7 .\" Based on glibc infopages
11 .TH NAN 3 2010-09-20 "GNU" "Linux Programmer's Manual"
13 nan, nanf, nanl \- return 'Not a Number'
17 .BI "double nan(const char *" tagp );
19 .BI "float nanf(const char *" tagp );
21 .BI "long double nanl(const char *" tagp );
26 Feature Test Macro Requirements for glibc (see
27 .BR feature_test_macros (7)):
35 _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
36 _POSIX_C_SOURCE\ >=\ 200112L;
43 These functions return a representation (determined by
46 If the implementation does not support
47 quiet NaNs, these functions return zero.
50 .I nan("char-sequence")
54 strtod("NAN(char-sequence)", NULL);
61 are equivalent to analogous calls to
68 is used in an unspecified manner.
69 On IEEE 754 systems, there are many representations of NaN, and
72 On other systems it may do nothing.
74 These functions first appeared in glibc in version 2.1.
77 See also IEC 559 and the appendix with
78 recommended functions in IEEE 754/IEEE 854.
84 This page is part of release 3.68 of the Linux
87 A description of the project,
88 information about reporting bugs,
89 and the latest version of this page,
91 \%http://www.kernel.org/doc/man\-pages/.