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Java Program to check if matrix is lower triangular

  • Last Updated : 17 Jan, 2022

Given a square matrix and the task is to check the matrix is in lower triangular form or not. A square matrix is called lower triangular if all the entries above the main diagonal are zero. 
 

Examples: 
 

Input : mat[4][4] = {{1, 0, 0, 0},
                     {1, 4, 0, 0},
                     {4, 6, 2, 0},
                     {0, 4, 7, 6}};
Output : Matrix is in lower triangular form.

Input : mat[4][4] = {{1, 0, 0, 0},
                     {4, 3, 0, 1},
                     {7, 9, 2, 0},
                     {8, 5, 3, 6}};
Output : Matrix is not in lower triangular form.

 

Java




// Java Program to check for 
// a lower triangular matrix.
import java.io.*;
  
class Lower_triangular
{
    int N = 4;
  
    // Function to check matrix is 
    // in lower triangular form or not.
    boolean isLowerTriangularMatrix(int mat[][])
    {
        for (int i = 0; i < N; i++)
            for (int j = i + 1; j < N; j++)
                if (mat[i][j] != 0)
                    return false;
  
        return true;
    }
  
    // Driver function.
    public static void main(String args[])
    {
        Lower_triangular ob = new Lower_triangular();
        int mat[][] = { { 1, 0, 0, 0 },
                        { 1, 4, 0, 0 },
                        { 4, 6, 2, 0 },
                        { 0, 4, 7, 6 } };
                          
        // Function call
        if (ob.isLowerTriangularMatrix(mat))
            System.out.println("Yes");
        else
            System.out.println("No");
    }
}
  
// This code is contributed by Anshika Goyal.

Output: 
 

Yes

Please refer complete article on Program to check if matrix is lower triangular for more details!


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