fma, fmaf, fmal - floating-point multiply and add
#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
These functions compute
x *
y +
z. The result is rounded as
one ternary operation according to the current rounding mode (see
fenv(3)).
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.
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.
These functions first appeared in glibc in version 2.1.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
fma (), fmaf (), fmal () |
Thread safety |
MT-Safe |
C99, POSIX.1-2001, POSIX.1-2008.
remainder(3),
remquo(3)