How to add two matrix in java Program

import java.util.Scanner;

class AddTwoMatrix {
  public static void main(String args[]) {
    int m, n, c, d;

    // Create scanner object to take input
    Scanner in = new Scanner(System.in);

    // Taking number of rows and columns as input
    System.out.println("Enter the number of rows and columns of matrix");
    m = in.nextInt();
    n = in.nextInt();

    // Declare matrices
    int first[][] = new int[m][n];
    int second[][] = new int[m][n];
    int sum[][] = new int[m][n];

    // Taking elements of first matrix as input
    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();
      }
    }

    // Taking elements of second matrix as input
    System.out.println("Enter the elements of second matrix");
    for (c = 0; c < m; c++) {
      for (d = 0; d < n; d++) {
        second[c][d] = in.nextInt();
      }
    }

    // Add the two matrices
    for (c = 0; c < m; c++) {
      for (d = 0; d < n; d++) {
        sum[c][d] = first[c][d] + second[c][d]; // replace '+' with '-' to subtract matrices
      }
    }

    // Display the sum of matrices
    System.out.println("Sum of entered matrices:");
    for (c = 0; c < m; c++) {
      for (d = 0; d < n; d++) {
        System.out.print(sum[c][d] + "\t");
      }
      System.out.println();
    }

    // Close the scanner to prevent resource leak
    in.close();
  }
}

Step-by-Step Explanation:

1. Importing Scanner Class:

import java.util.Scanner;

This imports the Scanner class from java.util to read from the user.

2. Class Definition:

class AddTwoMatrix

A class AddTwoMatrix is declared that contains the main method from where the program execution starts.

3. Main Method:

public static void main(String args[])

The main method is the entry point of the program. The program starts executing from here.

4. Declaring Variables:

int m, n, c, d;

Scanner in = new Scanner(System.in);

• m and n are variables to store the number of rows and columns of the matrices.
• c and d are loop counters for traversing the rows and columns of the matrices.
• Scanner in = new Scanner(System.in) is a Scanner object named in to read user input.

5. Input the Matrix Dimensions:

System.out.println(“Enter the number of rows and columns of matrix”);

m = in.nextInt();

n = in.nextInt();

• The program asks the user to input the number of rows (m) and columns (n) for the matrices.
• The user enters the values for m and n.

6. Matrix Declaration:

int first[][] = new int[m][n];

int second[][] = new int[m][n];

int sum[][] = new int[m][n];

Three 2D arrays are declared:

• first[][]: To hold elements of the first matrix.
• second[][]: To hold elements of the second matrix.
• sum[][]: To hold the sum of the two matrices.

7. Input the Elements of the First Matrix:

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();

• The program asks the user to input the elements of the first matrix.
• Two nested for loops are used:
  • The outer loop (c) loops through rows.
  • The inner loop (d) loops through the column.

The elements of the first matrix are given from the keyboard that is located at first[c][d].

8.  Enter the Elements of Second Matrix:

System.out.println(“Enter the elements of second matrix”);

for (c = 0; c < m; c++)

    for (d = 0; d < n; d{})

         second[c][d] = in.nextInt();

The above program asks for elements of the second matrix

Stored in the second array using nested for loops: for (c=0; c<m;c++)

for(d=0; d<n; d++)

9. Adding the Two Matrices:

for (c = 0; c < m; c)

    for (d = 0; d < n; d++)

        sum[c][d] = first[c][d] + second[c][d];

• A nested for loop is employed to add up the corresponding elements of the two matrices, viz. first[c][d] and second[c][d].
• The addition of the elements is stored in the sum[c][d] matrix.

10. Print out the Final Sum Matrix:

System.out.println(“Sum of entered matrices:-“);

for (c = 0; c < m; c++)

     for (d = 0; d < n; d++)

            System.out.print(sum[c][d] + “\t”);

            System.out.println()

• The program prints the sum of the matrices in a matrix format.
• The outer loop (c) iterates through the rows, and the inner loop (d) iterates through the columns.
• The sum of each element is printed, followed by a tab (\t) for formatting.

Sample Input and Output:

Sample 1:

Input:

Enter the number of rows and columns of matrix

2 2

Enter the elements of first matrix

1 2

3 4

Enter the elements of second matrix

5 6

7 8

Output:

Sum of entered matrices:-

6 8

10 12

Explanation:

Matrix 1:

  1  2

  3  4

Matrix 2:

5  6

7  8

Sum of the matrices:

  (1+5)  (2+6)   –>  6   8

  (3+7)  (4+8)   –>  10  12

Example 2:

Input: 

Enter the number of rows and columns of matrix

3 3

Enter the elements of first matrix

1 1 1

1 1 1

1 1 1

Enter the elements of second matrix

2 2 2

2 2 2

2 2 2

Output:

Sum of entered matrices:-

3 3 3 3

3 3 3 3

3 3 3 3

Key Points:

• Matrix Input: It takes input of elements for two matrices using nested loops.
• Matrix Addition: Adds corresponding elements of the two matrices and stores its value in the matrix sum[][].
• Matrix Output: The sum is displayed as a matrix for better readability using tab separation.

Time Complexity:

The time complexity for this program is (O(m times n)), where m is the number of rows and n is the number of columns, since we have to scan each element in the matrices once.

Space Complexity:

The space complexity is also (O(m times n)) since we have to store three matrices of size (m times n).