Standards
| Standards / Extensions |
C or C++ |
Dependencies |
|---|
C99
Single UNIX Specification, Version 3
C++ TR1 C99
|
both |
z/OS V1R7 |
Format
#define _ISOC99_SOURCE
#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);
C++
TR1 C99: #define _TR1_C99
#include <math.h>
float fma(float x, float y, float z);
long double fma(long double x, long double y, long double z);
General description
The fma() family of
functions compute (
x *
y)
+
z, rounded as one ternary operation: they
compute the value to infinite precision and round once to the resulting
format according to the rounding mode characterized by the value of
FLT_ROUNDS.
Note: The
following table shows the viable formats for these functions. See
IEEE binary floating-point for more information about IEEE
Binary Floating-Point.
| Function |
Hex |
IEEE |
|---|
| fma |
X |
X |
| fmaf |
X |
X |
| fmal |
X |
X |
Restriction: The
fmaf() function does not support the _FP_MODE_VARIABLE feature test
macro.
Returned value
If successful, they return
the rounded value of (x * y)
+ z as one ternary operation.