Name
fma, fmaf, fmal - floating-point multiply and addLibrary
Math library ( libm ", " -lm )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 );
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
fma() fmaf() fmal()
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
Description
These functions computex " * " 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 ofx " * " 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 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.
Attributes
For an explanation of the terms used in this section, see attributes(7).| Interface | Attribute | Value |
| T} | Thread safety | MT-Safe |