osx man page for nan

NAN(3)							   BSD Library Functions Manual 						    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, whose trailing fraction field contains the result of converting tagp to an unsigned integer.  If tagp
     is too large to be contained in the trailing fraction field of the NaN, then the least significant bits of the integer represented by tagp
     are used.

SPECIAL VALUES
     If tagp contains any non-numeric characters, the function returns a NaN whos trailing fraction field is zero.

     If tagp is empty, the function returns a NaN whos trailing fraction field is zero.

STANDARDS
     The nan() functions conform to ISO/IEC 9899:2011.

BSD
								   July 01, 2008							       BSD