NAN

NAN(3)                        libc math functions                       NAN(3)



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

SYNOPSIS
       #include <math.h>

       double nan(const char *tagp);

       float nanf(const char *tagp);

       long double nanl(const char *tagp);

DESCRIPTION
       These functions return a representation (determined by tagp) of a quiet
       NaN. If the implementation does not support quiet NaNs, these functions
       return zero.

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

       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)



GNU                               2002-08-10                            NAN(3)