NAN(3)

NAME
nan - generate a quiet NaN

SYNOPSIS
#include <math.h>
double
nan(const char *tagp);
long double
nanl(const char *tagp);
float
nanf(const char *tagp);

DESCRIPTION
The nan() functions return a quiet NaN. The character string tagp is converted to an integer, which is clipped to the range 0 to 255, inclusive. This value is used as the NaN code. The NaN code is placed in the 8th through 15th most significant bits of the fraction field of the resulting NaN.

SPECIAL VALUES
If tagp is empty, 0 is used for the NaN code.

STANDARDS
The nan() functions conform to ISO/IEC 9899:1999(E).