NAME

nan, nanf, nanl — return quiet NaN

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include <math.h>

double
nan(const char *tagp);

float
nanf(const char *tagp);

long double
nanl(const char *tagp);

DESCRIPTION

The call nan("n-char-sequence") is equivalent to the call strtod("NAN(n-char-sequence)", NULL). The call nan("") is equivalent to the call strtod("NAN()", NULL).

The nanf() and nanl() functions are equivalent to nan() but substituting strtof() and strtold(), respectively.

RETURN VALUES

IEEE 754

The nan(), nanf(), and nanl() functions return a quiet NaN as specified by tagp.

VAX

The nan(), nanf(), and nanl() functions return zero.

STANDARDS

The nan(), nanf(), and nanl() functions conform to ISO/IEC 9899:1999 (“ISO C99”).