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   infinity    ( 3 )

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Имя (Name)

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

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Синопсис (Synopsis)

#define _ISOC99_SOURCE      /* See feature_test_macros(7) */
       #include <math.h>

       INFINITY

       NAN

       HUGE_VAL
       HUGE_VALF
       HUGE_VALL

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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.

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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.

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Смотри также (See also)

fpclassify(3), math_error(7)

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