nan(), nanf(), nanl()

Return a quiet NaN

Synopsis:

#include <math.h>

double nan( const char *tagp );

float nanf( const char *tagp );

long double nanl( const char *tagp );

Arguments:

tagp
NULL, or an n-char sequence.

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

The nan(), nanf(), and nanl() functions return a quiet NaN, if available, with content indicated through tagp.

Calls to nan() are equivalent to calls to strtod(), as shown below:

This call: Is equivalent to:
nan("n-char-sequence") strtod("NAN(n-char-sequence)", (char **) NULL)
nan("") strtod("NAN()", (char **) NULL)
nan(tagp), where tagp doesn't point to an n-char sequence or an empty string strtod("NAN", (char **) NULL)

Calls to nanf() and nanl() are equivalent to the corresponding calls to strtof() and strtold().

Returns:

A quiet NaN, if available, with content indicated through tagp.

Classification:

ANSI, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler No
Thread Yes