The
fma()function takes three arguments x, y and z, and returnsx*y+zwithout losing precision. It is defined in <cmath> header file.
Syntax
fma(double x, double y, double z)
Parameters
The fma() takes three arguments.
x– The first argument to be multiplied.y– The second argument to be multiplied with x.z– The third argument to be added to the product of x and y.
Return value
Returns x*y+z as if calculated to infinite precision and rounded once to fit the result type.
fma() prototype [As of C++ 11 standard]
double fma(double x, double y, double z); float fma(float x, float y, float z); long double fma(long double x, long double y, long double z); Promoted fma(Type1 x, Type2 y, Type z);
Example : C++ fma()
#include <stdio.h> #include <math.h> int main () { double x,y,z,result; x = 11.0, y = 22.0, z = 33.0; #ifdef FP_FAST_FMA result = fma(x,y,z); #else result = x*y+z; #endif printf ("11.0 * 22.0 + 33.0 = %f\n", result); return 0; }
Output
11.0 * 22.0 + 33.0 = 275.000000