Section (3) INFINITY
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
to a float constant representing
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
HUGE_VALL expand to constants of types
double, float and long
double, respectively, that represent a large positive
value, possibly positive infinity.
On a glibc system, the macro
HUGE_VAL is always available. Availability
NAN macro can be tested
using #ifdef NAN, and
HUGE_VALL. They will be defined by
_GNU_SOURCE is defined, or
__STDC_VERSION__ is defined and has a value
not less than 199901L.
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