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   fmal    ( 3 )

умножение с плавающей запятой и сложение (floating-point multiply and add)

Имя (Name)

fma, fmaf, fmal - floating-point multiply and add


Синопсис (Synopsis)

#include <math.h>

double fma(double x, double y, double z); float fmaf(float x, float y, float z); long double fmal(long double x, long double y, long double z);

Link with -lm.

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

fma(), fmaf(), fmal(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L


Описание (Description)

These functions compute x * y + z. The result is rounded as one ternary operation according to the current rounding mode (see fenv(3)).


Возвращаемое значение (Return value)

These functions return the value of x * y + z, rounded as one ternary operation.

If x or y is a NaN, a NaN is returned.

If x times y is an exact infinity, and z is an infinity with the opposite sign, a domain error occurs, and a NaN is returned.

If one of x or y is an infinity, the other is 0, and z is not a NaN, a domain error occurs, and a NaN is returned.

If one of x or y is an infinity, and the other is 0, and z is a NaN, a domain error occurs, and a NaN is returned.

If x times y is not an infinity times zero (or vice versa), and z is a NaN, a NaN is returned.

If the result overflows, a range error occurs, and an infinity with the correct sign is returned.

If the result underflows, a range error occurs, and a signed 0 is returned.


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:

Domain error: x * y + z, or x * y is invalid and z is not a NaN An invalid floating-point exception (FE_INVALID) is raised.

Range error: result overflow An overflow floating-point exception (FE_OVERFLOW) is raised.

Range error: result underflow An underflow floating-point exception (FE_UNDERFLOW) is raised.

These functions do not set errno.


Версии (Versions)

These functions first appeared in glibc in version 2.1.


Атрибуты (Attributes)

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

┌──────────────────────────────────────┬───────────────┬─────────┐ │Interface Attribute Value │ ├──────────────────────────────────────┼───────────────┼─────────┤ │fma(), fmaf(), fmal() │ Thread safety │ MT-Safe │ └──────────────────────────────────────┴───────────────┴─────────┘


Стандарты (Conforming to)

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


Смотри также (See also)

remainder(3), remquo(3)