INFINITY
Section: Linux Programmer's Manual (3)
Updated: 20070726
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NAME
INFINITY, NAN, HUGE_VAL, HUGE_VALF, HUGE_VALL  floatingpoint constants
SYNOPSIS
#define _ISOC99_SOURCE /* See feature_test_macros(7) */
#include <math.h>
INFINITY
NAN
HUGE_VAL
HUGE_VALF
HUGE_VALL
DESCRIPTION
The macro
INFINITY
expands to a
float
constant representing positive infinity.
The macro
NAN
expands to a
float
constant representing a quiet NaN
(when supported).
A
quiet
NaN is a NaN ("notanumber") that does not raise exceptions
when it is used in arithmetic.
The opposite is a
signaling
NaN.
See IEC 60559:1989.
The macros
HUGE_VAL,
HUGE_VALF,
HUGE_VALL
expand to constants of types
double,
float
and
long double,
respectively,
that represent a large positive value, possibly plus infinity.
CONFORMING TO
C99.
AVAILABILITY
On a glibc system, the macro
HUGE_VAL
is always available.
Availability of the
NAN
macro can be tested using
#ifdef NAN,
and similarly for
INFINITY,
HUGE_VALF,
HUGE_VALL.
They will be defined by
<math.h>
if
_ISOC99_SOURCE
or
_GNU_SOURCE
is defined, or
__STDC_VERSION__
is defined
and has a value not less than 199901L.
SEE ALSO
fpclassify(3),
math_error(7)
COLOPHON
This page is part of release 3.54 of the Linux
manpages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/manpages/.
Index
 NAME

 SYNOPSIS

 DESCRIPTION

 CONFORMING TO

 AVAILABILITY

 SEE ALSO

 COLOPHON

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