NAN
NAME
nan, nanf, nanl - return 'Not a Number'
SYNOPSIS
#include <math.h>
I double nan(const char * tagp );
I float nanf(const char * tagp );
I long double nanl(const char * tagp );
Compile with -std=c99; link with -lm.
DESCRIPTION
These functions return a representation (determined by
R 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
R nanf ()
and
R nanl ()
are equivalent to analogous calls to
strtof(3)
and
strtold(3).
The argument
tagp
is used in an unspecified manner.
On IEEE 754 systems, 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
