Java Matrix Multiplication

[Vikash Jain]

Hi All,

Need help to understand if the code below for Matrix Multiplication is Correct. I was reading the blog and was a bit confused. If this is correct please tell me this will save my assignment.

---

import java.util.Scanner;

public class MatrixMultiplicationExample{
public static void main(String args[]){

int row1, col1, row2, col2;
Scanner s = new Scanner(System.in);
System.out.print("Enter number of rows in first matrix:");
row1 = s.nextInt();
System.out.print("Enter number of columns in first matrix:");
col1 = s.nextInt();
System.out.print("Enter number of rows in second matrix:");
row2 = s.nextInt();
System.out.print("Enter number of columns in second matrix:");
col2 = s.nextInt();

if (col1 != row2) {
System.out.println("Matrix multiplication is not possible");
}
else {
int a[][] = new int[row1][col1];
int b[][] = new int[row2][col2];
int c[][] = new int[row1][col2];

System.out.println("Enter values for matrix A : \n");
for (int i = 0; i < row1; i++) {
for (int j = 0; j < col1; j++)
a[i][j] = s.nextInt();
}
System.out.println("Enter values for matrix B : \n");
for (int i = 0; i < row2; i++) {
for (int j = 0; j < col2; j++)
b[i][j] = s.nextInt();
}

System.out.println("Matrix multiplication is : \n");
for(int i = 0; i < row1; i++) {
for(int j = 0; j < col2; j++){
c[i][j]=0;
for(int k = 0; k < col1; k++){
c[i][j] += a[i][k] * b[k][j];
}
System.out.print(c[i][j] + " ");
}
System.out.println();
}
}
}
}

---

The code is taken from here 

[Harshavardhan Bajoria]

According to me the code works perfectly fine !!

You may optimise the run time of the code using Strassen’s Matrix Multiplication. 

Happy Coding !!