Java Program to find Multiplication of Diagonal Elements of a Matrix

In the previous article, we have discussed Java Program to find Sum of Diagonal Elements of a Matrix

In this article we are going to see how we can write a program to calculate the product of both diagonal elements of a matrix in JAVA language.

Program to find Multiplication of Diagonal Elements of a Matrix

A 3*3 Matrix is having 3 rows and 3 columns where this 3*3 represents the dimension of the matrix. Means there are 3*3 i.e. total 9 elements in a 3*3 Matrix.

Let’s understand it in more simpler way.

                   | A00   A01   A02 |
Matrix A =  | A10   A11   A12 |
                   | A20   A21   A22 | 3*3

Matrix A represents a 3*3 matrix.
‘A‘ represents the matrix element
‘Aij‘ represents the matrix element at it’s matrix position/index.
‘i‘ represents the row index
‘j‘ represents the column index
Means A00=Aij where i=0 and j=0, A01=aij where i=0 and j=1 and like this.
Here we have started row value from 0 and column value from 0.

Let’s see different ways to find Multiplication of Diagonal Elements of a Matrix.

By Static Initialization of Array Elements
By Dynamic Initialization of Array Elements

Method-1: Java Program to find Multiplication of Diagonal Elements of a Matrix By Static Initialization of Array Elements

Approach:

Initialize an array of size 3×3 with values.
Show the array to the user.
Use two for loops to iterate the rows and columns, then multiply both the diagonal elements.
Print the output.

Program:

public class Matrix{
    public static void main(String args[])
    {
        // Initializing the 3X3 matrix i.e. 2D array
        int arr[][] = {{1,2,3},{4,5,6},{7,8,9}};
        int row, col;
        long primaryProd = 1, secondaryProd =1;
        // Printing the matrix using our user-defined function
        printMatrix(arr);

        // Loops to find the product
        for(row=0;row<3;row++)
            for(col=0;col<3;col++)
            {   
                // Only goes in if the element is a diagonal element
                if(row==col)
                    primaryProd *= arr[row][col];
                if(row+col==2)
                    secondaryProd *= arr[row][col];
            }
        System.out.println("\nProduct of left diagonal : "+primaryProd);
        System.out.println("Product of right diagonal : "+secondaryProd);
        
        System.out.println("The product of both diagonal elements are : "+(primaryProd*secondaryProd));
    }

    // Function to print the matrix
    static void printMatrix(int arr[][])
    {
        int row, col;
        System.out.print("The matrix elements are");
        // Loop to print the elements
        for(row=0;row<3;row++)
        {
            // Used for formatting
            System.out.print("\n");
            for(col=0;col<3;col++)
            {
                System.out.print(arr[row][col]+" ");
            }
        }
    }
}

Output:

The matrix elements are
1 2 3 
4 5 6 
7 8 9 
Product of left diagonal : 45
Product of right diagonal : 105
The product of both diagonal elements are : 4725

Method-2: Java Program to find Multiplication of Diagonal Elements of a Matrix By Dynamic Initialization of Array Elements

Approach:

Initialize an array of size 3×3.
Ask the user for input.
Use two for loops to iterate the rows and columns to input the array elements.
Use two for loops to iterate the rows and columns, then multiply both the diagonal elements.
Print the output.

Program:

import java.util.Scanner;
public class Matrix{
    public static void main(String args[])
    {
        //Scanner class to take input
        Scanner scan = new Scanner(System.in);

        // Delclaring the 3X3 matrix i.e. 2D array
        int arr[][] = new int[3][3];
        int row, col, primaryProd = 1, secondaryProd=1;
        
        // Taking the matrix as input
        System.out.println("Enter the matrix elements : ");
        for(row=0;row<3;row++)
            for(col=0;col<3;col++)
                arr[row][col] = scan.nextInt();
                
        System.out.print("Matrix : "); 
        // Loop to print the elements 
        for(row=0;row<3;row++) 
        { 
            // Used for formatting 
            System.out.print("\n"); 
            for(col=0;col<3;col++) 
            { 
                System.out.print(arr[row][col]+" "); 
            } 
        }

        // Loops to find the product
        for(row=0;row<3;row++)
            for(col=0;col<3;col++)
            {   
                // Only goes in if the element is a diagonal element
                if(row==col)
                    primaryProd *= arr[row][col];
                if(row+col==2)
                    secondaryProd *= arr[row][col];
            }
        System.out.println("\nThe product of left diagonal elements is : "+primaryProd);
        System.out.println("The product of right diagonal elements is : "+secondaryProd);
        System.out.println("The product of both diagonal elements is : "+(primaryProd*secondaryProd));
    }
}

Output:

Enter the matrix elements : 1 2 3 4 5 6 7 8 9
Matrix : 
1 2 3 
4 5 6 
7 8 9 
The product of left diagonal elements is : 45
The product of right diagonal elements is : 105
The product of both diagonal elements is : 4725

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