Java Program to Multiply two or More Matrices

Back
Table Of Contents
  1. How Matrices are Multiplied
  2. Algorithm/Program Explanation
  3. Example-1 Taking Static Inputs:
  4. Example-2 Taking User Defined Inputs
  5. Question Asked in This Topics
  6. Related Topics:

Java Program to Multiply two or more matrices is one of the most frequently asked interview and coding question,therefore it is necessary to understand logic to implement this program.Don’t worry I will make you understand it. In this topic we will see two examples.In Example-1 we will take Static Inputs(Pre-defined Inputs). And in Example-2 we will take User defined Inputs.

How Matrices are Multiplied

MatrixMultiplication.jpeg
Lets take 1st row of matrix1 and all three columns of matrix3
 [1  2  3]  X | 1 2 3 |
              | 1 2 3 |
              | 1 2 3 |
  
[ 1*1+2*1+3*1  1*2+2*2+3*2 1*3+2*3+3*3]
Procedure:-

1.Here 1st element of first row of matrix1 is multiplied with 1st element of first columns of matrix2 i.e 1*1.
2.Then 2nd element of first row of matrix1 is multiplied with 2nd element of first columns of matrix2 i.e 2*1
3.Then 3rd element of first row of matrix1 is multiplied with 3rd element of first columns of matrix2 i.e 3*1
4.Now add all the result of multiplication i.e. 1+2+3=6
5. '6' is the first entry for matrix3
Note:In this way fill more 8 entries in matrix3

Algorithm/Program Explanation

  1. Start
  2. define and initialize three 2d array
    • int matrix1[][]={{1,2,3}, {1,2,3}, {1,2,3}};
    • int matrix2[][]={{1,2,3}, {1,2,3}, {1,2,3}};
    • int matrix3[][]=new int[3][3];// enter data accordingly
  3. Define Three for loop
    • for(int i=0;i<3;i++).
    • for(int j=0;j<3;j++)
    • for(int m=0;m<3;m++)
      • Condition:
      • matrix3[i][j]+=matrix1[i][m]*matrix2[m][j];
    • Print matrix3
  4. end

Example-1 Taking Static Inputs:

/*
Java Program for Matrix Multiplication */
import java.util.*;
public class MatrixMultiplication {
    public static void main(String args[]){
        int matrix1[][]={{1,2,3}, {1,2,3}, {1,2,3}};
        int matrix2[][]={{1,2,3}, {1,2,3}, {1,2,3}};
        int matrix3[][]=new int[3][3];
        System.out.println("Matrix After Multiplication:");
        for(int i=0;i<3;i++){
            for(int j=0;j<3;j++){

                for(int m=0;m<3;m++){
                    matrix3[i][j]+=matrix1[i][m]*matrix2[m][j];

            }System.out.print(matrix3[i][j]+ " ");

        }            System.out.println();
    }
}}


Output:
Matrix After Multiplication:
6 12 18 
6 12 18 
6 12 18

Example-2 Taking User Defined Inputs

/*
Java Program for Matrix Multiplication */
import java.util.*;
import java.util.Scanner;
public class MatrixMultiplication {
    public static void main(String args[]){
        Scanner sc=new Scanner(System.in);
        int matrix1[][]= new int [3][3];
        int matrix2[][]= new int [3][3];
        int matrix3[][]=new int[3][3];
        System.out.println("Enter The Elements of Matrix-1");
        for(int i=0;i<3;i++)
        { for(int j=0;j<3;j++){
            matrix1[i][j]=sc.nextInt();
        }

        }
        System.out.println("Enter The Elements of Matrix-2");
        for(int i=0;i<3;i++)
        { for(int j=0;j<3;j++){
            matrix2[i][j]=sc.nextInt();
        }

        }

        System.out.println("Matrix After Multiplication:");
        for(int i=0;i<3;i++){
            for(int j=0;j<3;j++){

                for(int m=0;m<3;m++){
                    matrix3[i][j]+=matrix1[i][m]*matrix2[m][j];

            }System.out.print(matrix3[i][j]+ " ");

        }            System.out.println();
    }
}}

Output:
Enter The Elements of Matrix-1
 1 2 3
 1 2 3
 1 2 3
Enter The Elements of Matrix-2
1 2 3
1 2 3
1 2 3
Matrix After Multiplication:
6 12 18 
6 12 18 
6 12 18

Question Asked in This Topics

  • Write a Java Program to Multiply two Matrices?
  • Derive a Logic for Matrix Multiplication
  • Given are the 2 matrices implement java logic multiply them?
  • Take user defined matrices and code a logic to multiply them?

Related Topics:

Leave a Comment