HP-UX Reference (11i v2 04/09) - 3 Library Functions N-Z (vol 7)

nan(3M) nan(3M)

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.