константы с плавающей запятой (floating-point constants)
Имя (Name)
INFINITY, NAN, HUGE_VAL, HUGE_VALF, HUGE_VALL - floating-point
constants
Синопсис (Synopsis)
#define _ISOC99_SOURCE /* See feature_test_macros(7) */
#include <math.h>
INFINITY
NAN
HUGE_VAL
HUGE_VALF
HUGE_VALL
Описание (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 positive infinity.
Стандарты (Conforming to)
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.
Смотри также (See also)
fpclassify(3), math_error(7)
