Java program to multiply two matrices


Levels of difficulty: / perform operation:

This java program multiply two matrices. Before multiplication matrices are checked whether they can be multiplied or not.

This java program

import java.util.Scanner;
class MatrixMultiplication {
	public static void main(String args[]) {
		int m, n, p, q, sum = 0, c, d, k;
		Scanner in = new Scanner(System.in);
		System.out.println("Enter the number of rows and columns of first matrix");
		m = in.nextInt();
		n = in.nextInt();
		int first[][] = new int[m][n];
		System.out.println("Enter the elements of first matrix");
		for ( c = 0 ; c < m ; c++ )
		         for ( d = 0 ; d < n ; d++ )
		            first[c][d] = in.nextInt();
		System.out.println("Enter the number of rows and columns of second matrix");
		p = in.nextInt();
		q = in.nextInt();
		if ( n != p )
		  System.out.println("Matrices with entered orders can't be multiplied "); 
                else {
			int second[][] = new int[p][q];
			int multiply[][] = new int[m][q];
			System.out.println("Enter the elements of second matrix");
			for ( c = 0 ; c < p ; c++ )
			            for ( d = 0 ; d < q ; d++ )
			               second[c][d] = in.nextInt();
			for ( c = 0 ; c < m ; c++ ) {
				for ( d = 0 ; d < q ; d++ ) {
					for ( k = 0 ; k < p ; k++ ) {
						sum = sum + first[c][k]*second[k][d];
					}
					multiply[c][d] = sum;
					sum = 0;
				}
			}
			System.out.println("Product of entered matrices:-");
			for ( c = 0 ; c < m ; c++ ) {
				for ( d = 0 ; d < q ; d++ )
				               System.out.print(multiply[c][d]+"\t");
				System.out.print("\n");
			}
		}
	}
}


Output

This is a basic method of multiplication, there are more efficient algorithms available. Also this approach is not recommended for sparse matrices which contains a large number of elements as zero.