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INFINITY

Section: C Library Functions (3)
Updated: 202-0-08
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NAME

INFINITY, NAN, HUGE_VAL, HUGE_VALF, HUGE_VALL - floatin-point constants

LIBRARY

Math library (libm)

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 ("no--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 positive infinity.

STANDARDS

C11.

HISTORY

C99. 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.