to check for Lower Triangular Matrix

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

Lower Triangular Matrix : A Lower Triangular matrix is a square matrix in which all the entries above the main diagonal (↘) are zero. The entries below or on the main diagonal themselves may or may not be zero.

Example:

import java.util.*;

class LowerTriangularMatrix

{

    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;

         

        for(int i=0;i<m;i++)

        {

            for(int j=i+1;j<m;j++)

            {

                /* Checking that the matrix is Lower Triangular or not */

                if(A[i][j]!=0) // All elements above the diagonal must be zero

                {

                    p=1;

                    break;

                }

            }

        }

         

        if(p==0)

            System.out.println("The matrix is Lower Triangular");

        else

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

    }

}




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 : 3
Enter an element : 1
Enter an element : 0
Enter an element : 0
Enter an element : 4
Enter an element : 9
Enter an element : 4
Enter an element : 0
Enter an element : 6
Enter an element : 8
Enter an element : 7
Enter an element : 2
*************************
The Matrix is :
5 0 0 0
3 1 0 0
4 9 4 0
6 8 7 2
*************************
The matrix is Lower Triangular