NAME
nan(), nanf(), nanl(), nanw(), nanq() — string-to-NaN conversion functions
SYNOPSIS
#include <math.h>
double nan(const char *tagp);
Itanium(R)-based System Only
float nanf(const char *tagp);
long double nanl(const char *tagp);
extended nanw(const char *tagp);
quad nanq(const char *tagp);
DESCRIPTION
The
nan()
function creates a quiet NaN from the specified string.
If
tagp
does not point to an
n-char-sequence
or an empty string, the call is equivalent to
strtod("NAN", (char**) NULL).
The ISO/IEC C99 standard specifies
n-char-sequence
syntax, but the interpretation and extension
of the syntax is implementation defined. The
n-char-sequence
argument is ignored on HP-UX systems.
Itanium-based System Only
nanf()
is a
float
version of
nan();
it returns a
float
result.
nanl()
is a
long double
version of
nan();
it returns a
long double
result.
nanw()
is an
extended
version of
nan();
it returns an
extended
result.
nanq()
is equivalent to
nanl()
on HP-UX systems.
USAGE
To use these functions,
compile either with the default
-Ae
option or with the
-Aa
and
-D_HPUX_SOURCE
options. To use
nanw()or
nanq(),
compile with the
-fpwidetypes
option. Make sure your program includes
<math.h>,
and link in the math library by specifying
-lm
on the compiler or linker command line.
For more information, see the
HP-UX Floating-Point Guide.
RETURN VALUE
The
nan()
function returns a quiet NaN.
These functions raise no exceptions.
ERRORS
No errors are defined.
STANDARDS CONFORMANCE
nan(),
nanf(),
nanl()
: ISO/IEC C99 (including Annex F, "IEC 60559 floating-point arithmetic")
