FMA(3) Linux Programmer's Manual FMA(3)
NAME
fma, fmaf, fmal - floating-point 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 oppo-
site 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 re-
turned.
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 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.
VERSIONS
These functions first appeared in glibc in version 2.1.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
+----------------------+---------------+---------+
|Interface | Attribute | Value |
+----------------------+---------------+---------+
|fma(), fmaf(), fmal() | Thread safety | MT-Safe |
+----------------------+---------------+---------+
CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
SEE ALSO
remainder(3), remquo(3)
COLOPHON
This page is part of release 5.07 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
2017-09-15 FMA(3)