Section (3) fma
fma, fmaf, fmal — floating-point multiply and add
||long double x,|
|long double y,|
|long double z
These functions compute
z. The result is rounded as one
ternary operation according to the current rounding mode (see
These functions return the value of
z, rounded as one ternary
y is a NaN, a NaN is
y is an exact
z is an
infinity with the opposite sign, a domain error occurs, and a
NaN is returned.
If one of
y is an infinity, the
other is 0, and
not a NaN, a domain error occurs, and a NaN is returned.
If one of
y is an infinity, and
the other is 0, and
is a NaN, a domain error occurs, and a NaN is returned.
y is not an infinity
times zero (or vice versa), and
z is a NaN, a NaN is
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.
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:
yis invalid and
zis 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
For an explanation of the terms used in this section, see attributes(7).
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Copyright 2002 Walter Harms (walter.harmsinformatik.uni-oldenburg.de)
and Copyright 2008, Linux Foundation, written by Michael Kerrisk
Distributed under GPL
Modified 2004-11-15, Added further text on FLT_ROUNDS
as suggested by AEB and Fabian Kreutz