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   copysign    ( 3 )

копировать знак числа (copy sign of a number)

Имя (Name)

copysign, copysignf, copysignl - copy sign of a number

Синопсис (Synopsis)

#include <math.h>

double copysign(double x, double y); float copysignf(float x, float y); long double copysignl(long double x, long double y);

Link with -lm.

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

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


Описание (Description)

These functions return a value whose absolute value matches that
       of x, but whose sign bit matches that of y.

For example, copysign(42.0, -1.0) and copysign(-42.0, -1.0) both return -42.0.


Возвращаемое значение (Return value)

On success, these functions return a value whose magnitude is
       taken from x and whose sign is taken from y.

If x is a NaN, a NaN with the sign bit of y is returned.


Ошибки (Error)

No errors occur.

Атрибуты (Attributes)

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

┌──────────────────────────────────────┬───────────────┬─────────┐ │Interface Attribute Value │ ├──────────────────────────────────────┼───────────────┼─────────┤ │copysign(), copysignf(), copysignl() │ Thread safety │ MT-Safe │ └──────────────────────────────────────┴───────────────┴─────────┘


Стандарты (Conforming to)

C99, POSIX.1-2001, POSIX.1-2008.  This function is defined in IEC
       559 (and the appendix with recommended functions in IEEE 754/IEEE
       854).

Примечание (Note)

On architectures where the floating-point formats are not IEEE
       754 compliant, these functions may treat a negative zero as
       positive.

Смотри также (See also)

signbit(3)