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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | ATTRIBUTES | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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nan(3) Library Functions Manual nan(3)
nan, nanf, nanl - return 'Not a Number'
Math library (libm, -lm)
#include <math.h>
double nan(const char *tagp);
float nanf(const char *tagp);
long double nanl(const char *tagp);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
nan(), nanf(), nanl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
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.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────┬───────────────┬────────────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────┼───────────────┼────────────────┤
│ nan(), nanf(), nanl() │ Thread safety │ MT-Safe locale │
└──────────────────────────────┴───────────────┴────────────────┘
C11, POSIX.1-2008.
See also IEC 559 and the appendix with recommended functions in
IEEE 754/IEEE 854.
glibc 2.1. C99, POSIX.1-2001.
isnan(3), strtod(3), math_error(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
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⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.9.1 2024-05-02 nan(3)
Pages that refer to this page: strtod(3), math_error(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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