What is fmal in C?

fmal is a mathematical function in C that multiplies two values together. It then adds a third value and rounds the result, ensuring correct precision while intermediary rounding.

Syntax

long double fmal(
   long double  x,
   long double  y,
   long double z
);

Parameters

  • x is the first value to multiply.
  • y is the second value to multiply.
  • z is the value to add.

Return value

The function returns the value of (x*y) + z as calculated to infinite precision and rounded once to adjust according to the result data type.

The following table lists some values on which the function returns other values:

Input Returned value
x = INFINITY, y = 0 or x = 0, y = INFINITY NaN
x or y = exact ± INFINITY, z = INFINITY with the opposite sign NaN
x or y = NaN NaN
Overflow range error ±HUGE_VAL, ±HUGE_VALF, or ±HUGE_VALL
Underflow range error correct value, after rounding.

Example

The following code shows how to use the fmal function in C – we store the result of the computation in fmal_result and print it as a floating point value:

#include<stdio.h>
#include <math.h>
int main() {
  double fmal_result = fmal(0.01,10,0.001); //calling the function fmal
  printf("fmal(0.01,10,0.001) = %f\n", fmal_result);//
}

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