NANSection: Linux Programmer's Manual (3)
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NAMEnan, nanf, nanl - return 'Not a Number'
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)):
DESCRIPTIONThese 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:
VERSIONSThese functions first appeared in glibc in version 2.1.
CONFORMING TOC99, POSIX.1-2001. See also IEC 559 and the appendix with recommended functions in IEEE 754/IEEE 854.
SEE ALSOisnan(3), strtod(3), math_error(7)
COLOPHONThis page is part of release 3.21 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.