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   ldexp    ( 3 )

умножить число с плавающей запятой на целую степень 2 (multiply floating-point number by integral power of 2)

Имя (Name)

ldexp, ldexpf, ldexpl - multiply floating-point number by
       integral power of 2

Синопсис (Synopsis)

#include <math.h>

double ldexp(double x, int exp); float ldexpf(float x, int exp); long double ldexpl(long double x, int exp);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

ldexpf(), ldexpl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE


Описание (Description)

These functions return the result of multiplying the floating-
       point number x by 2 raised to the power exp.

Возвращаемое значение (Return value)

On success, these functions return x * (2^exp).

If exp is zero, then x is returned.

If x is a NaN, a NaN is returned.

If x is positive infinity (negative infinity), positive infinity (negative infinity) is returned.

If the result underflows, a range error occurs, and zero is returned.

If the result overflows, a range error occurs, and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively, with a sign the same as x.


Ошибки (Error)

See math_error(7) for information on how to determine whether an
       error has occurred when calling these functions.

The following errors can occur:

Range error, overflow errno is set to ERANGE. An overflow floating-point exception (FE_OVERFLOW) is raised.

Range error, underflow errno is set to ERANGE. An underflow floating-point exception (FE_UNDERFLOW) is raised.


Атрибуты (Attributes)

For an explanation of the terms used in this section, see
       attributes(7).

┌──────────────────────────────────────┬───────────────┬─────────┐ │Interface Attribute Value │ ├──────────────────────────────────────┼───────────────┼─────────┤ │ldexp(), ldexpf(), ldexpl() │ Thread safety │ MT-Safe │ └──────────────────────────────────────┴───────────────┴─────────┘


Стандарты (Conforming to)

C99, POSIX.1-2001, POSIX.1-2008.

The variant returning double also conforms to SVr4, 4.3BSD, C89.


Смотри также (See also)

frexp(3), modf(3), scalbln(3)