unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (Debian-5.0)
Page:
Section:
Apropos / Subsearch:
optional field

NAN(3)                     Linux Programmer's Manual                    NAN(3)



NAME
       nan, nanf, nanl - return 'Not a Number'

SYNOPSIS
       #include <&lt;math.h>&gt;

       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;  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 func-
       tions return zero.

       The  call  nan("char-sequence")  is  equivalent  to   strtod("NAN(char-
       sequence)",  NULL) and similarly calls to nanf() and nanl() are equiva-
       lent to analogous calls to strtof(3) and strtold(3).

       The argument tagp is used in an unspecified manner.  On IEEE  754  sys-
       tems,  there are many representations of NaN, and tagp selects one.  On
       other systems it may do nothing.

CONFORMING TO
       C99.  See also IEC 559 and the appendix with recommended  functions  in
       IEEE 754/IEEE 854.

SEE ALSO
       isnan(3), strtod(3), math_error(7)

COLOPHON
       This  page  is  part of release 3.05 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/.



GNU                               2008-07-23                            NAN(3)