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)
