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

#define _ISOC99_SOURCE

#include <math.h>
 INFINITY
 NAN
 HUGE_VAL

HUGE_VALF

HUGE_VALL

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 R HUGE_VAL , R HUGE_VALF , R HUGE_VALL expand to constants of types double, float and long double, respectively, that represent a large positive value, possibly plus infinity.

C99

On a glibc system, the macro HUGE_VAL is always available. Availability of the NAN macro can be tested using R #ifdef NAN , and similarly for R INFINITY , R HUGE_VALF , R 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.

fpclassify(3), feature_test_macros(7)