Section (3) fma
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) ; 
Note  


Note  

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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
, orx
*y
is invalid andz
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
.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
Interface  Attribute  Value 
fma (), fmaf (), fmal () 
Thread safety  MTSafe 
COLOPHON
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Copyright 2002 Walter Harms (walter.harmsinformatik.unioldenburg.de) and Copyright 2008, Linux Foundation, written by Michael Kerrisk <mtk.manpagesgmail.com> %%%LICENSE_START(GPL_NOVERSION_ONELINE) Distributed under GPL %%%LICENSE_END Modified 20041115, Added further text on FLT_ROUNDS as suggested by AEB and Fabian Kreutz 