Code:
import java.util.Random;
import java.util.Scanner;
public class Coppersmith_Freivalds_Algorithm
{
public static void main(String args[])
{
System.out.println("Enter the dimesion of the matrices: ");
Scanner input = new Scanner(System.in);
int n = input.nextInt();
System.out.println("Enter the 1st matrix: ");
double a[][] = new double[n][n];
for(int i=0; i
{
for(int j=0; j
{
a[i][j] = input.nextDouble();
}
}
System.out.println("Enter the 2st matrix: ");
double b[][] = new double[n][n];
for(int i=0; i
{
for(int j=0; j
{
b[i][j] = input.nextDouble();
}
}
System.out.println("Enter the result matrix: ");
double c[][] = new double[n][n];
for(int i=0; i
{
for(int j=0; j
{
c[i][j] = input.nextDouble();
}
}
//random generation of the r vector containing only 0/1 as its elements
double [][]r = new double[n][1];
Random random = new Random();
for(int i=0; i
{
r[i][0] = random.nextInt(2);
}
//test A * (b*r) - (C*) = 0
double br[][] = new double[n][1];
double cr[][] = new double[n][1];
double abr[][] = new double[n][1];
br = multiplyVector(b, r, n);
cr = multiplyVector(c, r, n);
abr = multiplyVector(a, br, n);
//check for all zeros in abr
boolean flag = true;
for(int i=0; i
{
if(abr[i][0] == 0)
continue;
else
flag = false;
}
if(flag == true)
System.out.println("Yes");
else
System.out.println("No");
input.close();
}
public static double[][] multiplyVector(double[][] a, double[][] b, int n)
{
double result[][] = new double[n][1];
for (int i = 0; i < n; i++)
{
for (int j = 0; j < 1; j++)
{
for (int k = 0; k < n; k++)
{
result[i][j] = result[i][j] + a[i][k] * b[k][j];
}
}
}
return result;
}
}
Output:
Enter the dimesion of the matrices:
2
Enter the 1st matrix:
2 3
3 4
Enter the 2st matrix:
1 0
1 2
Enter the result matrix:
6 5
8 7
Yes
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