nanf (3)
Leading comments
Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de) %%%LICENSE_START(GPL_NOVERSION_ONELINE) Distributed under GPL %%%LICENSE_END Based on glibc infopages Corrections by aeb
NAME
nan, nanf, nanl - return 'Not a Number'SYNOPSIS
#include <math.h>
double nan(const char *tagp);
float nanf(const char *tagp);
long double nanl(const char *tagp);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
nan(), nanf(), nanl():
-
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
DESCRIPTION
These functions return a representation (determined by tagp) of a quiet NaN. If the implementation does not support quiet NaNs, these functions return zero.The call nan(char-sequence) is equivalent to:
strtod("NAN(char-sequence)", NULL);
Similarly, calls to nanf() and nanl() are equivalent to analogous calls to strtof(3) and strtold(3).
The argument tagp is used in an unspecified manner. On IEEE 754 systems, there are many representations of NaN, and tagp selects one. On other systems it may do nothing.
VERSIONS
These functions first appeared in glibc in version 2.1.ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).Interface | Attribute | Value |
nan(), nanf(), nanl() | Thread safety | MT-Safe locale |