to check for Scalar Matrix

Write a Program in Java to input a 2-D square matrix and check whether it is a Scalar Matrix or not.

Scalar Matrix : A scalar matrix is a diagonal matrix in which the main diagonal () entries are all equal.

See : Java program to check for Diagonal Matrix

Example:

import java.util.*;

class ScalarMatrix

{

    public static void main(String args[])throws Exception

    {

        Scanner sc=new Scanner(System.in);

        System.out.print("Enter the size of the matrix : ");

        int m=sc.nextInt();

        int A[][]=new int[m][m];

         

        /* Inputting the matrix */

        for(int i=0;i<m;i++)

        {

            for(int j=0;j<m;j++)

            {

                System.out.print("Enter an element : ");

                A[i][j]=sc.nextInt();

            }

        }

 

        /* Printing the matrix */

        System.out.println("*************************");

        System.out.println("The Matrix is : ");

        for(int i=0;i<m;i++)

        {

            for(int j=0;j<m;j++)

            {

                System.out.print(A[i][j]+"\t");

            }

            System.out.println();

        }

        System.out.println("*************************");

         

        int p = 0, q = 0, x = A[0][0]; // 'x' is storing the 1st main diagonal element

         

        for(int i=0;i<m;i++)

        {

            for(int j=0;j<m;j++)

            {

                /* Checking that the matrix is diagonal or not */

                if(i!=j && A[i][j]!=0) // All non-diagonal elements must be zero

                {

                    p=1;

                    break;

                }

                /* Checking the matrix for scalarity */

                // All main diagonal elements must be equal to 'x' and non-zero

                if(i==j && (A[i][j]==0 || A[i][j]!=x))

                {

                    q=1;

                    break;

                }

            }

        }

         

        if(p==0 && q==0)

            System.out.println("The matrix is scalar");

        else

            System.out.println("The matrix is not scalar");

    }

}




Output:

Enter the size of the matrix : 4
Enter an element : 5
Enter an element : 0
Enter an element : 0
Enter an element : 0
Enter an element : 0
Enter an element : 5
Enter an element : 0
Enter an element : 0
Enter an element : 0
Enter an element : 0
Enter an element : 5
Enter an element : 0
Enter an element : 0
Enter an element : 0
Enter an element : 0
Enter an element : 5
*************************
The Matrix is :
5 0 0 0
0 5 0 0
0 0 5 0
0 0 0 5
*************************
The matrix is Scalar