INFINITY(3)

NAME
INFINITY, NAN, HUGE_VAL, HUGE_VALF, HUGE_VALL - floating-point constants

SYNOPSIS
#define _ISOC99_SOURCE
#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 ("not-a-number") 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), feature_test_macros(7), math_error(7)

COLOPHON
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