fma3
Floating-point multiply and add
Usage
#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);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
fma(), fmaf(), fmal():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
Library
Math library (libm, -lm)
Overview
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.
|
An invalid floating-point exception ( |
|---|---|
Range error: result overflow
|
An overflow floating-point exception ( |
Range error: result underflow
|
An underflow floating-point exception ( |
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 | MT-Safe |
Releases
12 releases since Debian 3.1 (Sarge); the text changed 11 times.
-1 until Debian 5.0 (Lenny).