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# Java program to check whether a given matrix is Lower Triangular Matrix or not

In this java program, we are reading a matrix and check whether input matrix is Lower Triangular Matrix or not. By IncludeHelp Last updated : December 23, 2023

## Problem statement

Given a matrix and we have to check whether it is Lower Triangular Matrixor not?

## Lower Triangular Matrix

A matrix is said to be lower matrix if all the elements above the diagonal of the given matrix are zero. So it is necessary that the elements must be zero.

### Example

```Enter the size of the matrix : 3
Enter an element : 0
Enter an element : 0
Enter an element : 0
Enter an element : 1
Enter an element : 0
Enter an element : 0
Enter an element : 1
Enter an element : 1
Enter an element : 0
*************************
The Matrix is :
0	0	0
1	0	0
1	1	0
*************************
The matrix is Lower Triangular
```

## Program to check matrix is Lower Triangular Matrix or not in java

```import java.util.Scanner;

public class ExArrayLowerMatrix {
public static void main(String args[]) throws Exception {
// create object of scanner class
Scanner sc = new Scanner(System.in);

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

int m = sc.nextInt();
int A[][] = new int[m][m];

// Input the matrix.
for (int i = 0; i < m; i++) {
for (int j = 0; j < m; j++) {
System.out.print("Enter the elements : ");
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++) {
// check for lower matrix or not.
if (A[i][j] != 0) {
p = 1;
break;
}
}
}

// print matrix is lower triangular or not.
if (p == 0)
System.out.println("The matrix is Lower Triangular");
else
System.out.println("The matrix is not Lower Triangular");
}
}
```

### Output

```First run:
Enter the size of the matrix : 5
Enter an element : 1
Enter an element : 2
Enter an element : 3
Enter an element : 4
Enter an element : 5
Enter an element : 6
Enter an element : 7
Enter an element : 8
Enter an element : 9
Enter an element : 1
Enter an element : 0
Enter an element : 12
Enter an element : 5
Enter an element : 9
Enter an element : 3
Enter an element : 6
Enter an element : 5
Enter an element : 8
Enter an element : 2
Enter an element : 5
Enter an element : 8
Enter an element : 2
Enter an element : 5
Enter an element : 2
Enter an element : 5
*************************
The Matrix is :
1	2	3	4	5
6	7	8	9	1
0	12	5	9	3
6	5	8	2	5
8	2	5	2	5
*************************
The matrix is not Lower Triangular

Second run:
Enter the size of the matrix : 3
Enter an element : 0
Enter an element : 0
Enter an element : 0
Enter an element : 1
Enter an element : 0
Enter an element : 0
Enter an element : 1
Enter an element : 1
Enter an element : 0
*************************
The Matrix is :
0	0	0
1	0	0
1	1	0
*************************
The matrix is Lower Triangular
```