The **`fma()`** ("fused multiply-add") ﻿function is used to compute the following expression: 

`fma()` computes the expression $(a * b + c)$ to infinite precision by computing the expression as a single ternary operation. The expression result is rounded off only once upto the decimal places that can fit in the output data type.


# Library
To use the `fma()` function, include the following library:
```C
#include <math.h>
```
# Syntax
The declaration of the `fma()` function is shown below:
```C
double fma (double a, double b, double c);
```
The `fma()` function computes the expression (`a` * `b` + `c`) on its input parameters and returns the result of the expression. 

# Code
Consider the code snippet below, which uses `fma()` to compute ( `a` * `b` + `c`):

#include <stdio.h>
#include <math.h>

int main() {

  double a = 1.556532;
  double b = 2.389987;
  double c = 0.147897;

  double x = fma(a, b, c);

  printf("fma ( %f, %f, %f ) = ( %lf ) \n", a, b, c, x);
  
  return 0;
}

gcc compiler

# Explanation
The `fma()` function is used in `line 10` to compute the expression (`a` * `b` + `c`) on variables `a`, `b`, and `c` that are created in `lines 5-8`.


gcc.tar.gz

What is fma() in C?

fma() computes (a * b + c) with single-step rounding using #include <math.h> in C.