INFINITY(3) manual page
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INFINITY, NAN, HUGE_VAL, HUGE_VALF, HUGE_VALL
- floating-point constants
#define _ISOC99_SOURCE /* See feature_test_macros(7) */
#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 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.
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.
fpclassify(3)
, math_error(7)
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