FMA
Section: Linux Programmer's Manual (3)
Updated: 20170915
Page Index
NAME
fma, fmaf, fmal  floatingpoint multiply and add
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
DESCRIPTION
These functions compute
x *
y +
z.
The result is rounded as one ternary operation according to the
current rounding mode (see
fenv(3)).
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.
ERRORS
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 floatingpoint exception
(FE_INVALID)
is raised.
 Range error: result overflow

An overflow floatingpoint exception
(FE_OVERFLOW)
is raised.
 Range error: result underflow

An underflow floatingpoint exception
(FE_UNDERFLOW)
is raised.
These functions do not set
errno.
VERSIONS
These functions first appeared in glibc in version 2.1.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
Interface  Attribute  Value

fma(),
fmaf(),
fmal()
 Thread safety  MTSafe

CONFORMING TO
C99, POSIX.12001, POSIX.12008.
SEE ALSO
remainder(3),
remquo(3)
COLOPHON
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project.
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