# Java Program to display upper triangular matrix

In this article, we will understand how to display an upper triangular matrix. The matrix has a row and column arrangement of its elements. A matrix with m rows and n columns can be called as m × n matrix. An upper triangular matrix is a triangular matrix with all elements below the main diagonal are 0.

Below is a demonstration of the same −

Suppose our input is

The matrix is defined as:
2 1 4
1 2 3
3 6 2

The desired output would be

The upper triangular matrix is:
2 1 4
0 2 3
0 0 2

## Algorithm

Step 1 - START
Step 2 - Declare an integer matrix namely input_matrix.
Step 3 - Define the values.
Step 4 - Iterate over each element of the matrix using two for-loops, assign 0 to all the [i][j] positions that comes below the diagonal of the matrix using rows != column condition.
Step 5 - Display the matrix as result
Step 6 - Stop

## Example 1

Here, we bind all the operations together under the ‘main’ function.

public class UpperTriangle {
public static void upper_triangular_matrix(int input_matrix[][]) {
}
public static void main(String[] args) {
int input_matrix[][] = {
{ 2, 1, 4 },
{ 1, 2, 3 },
{ 3, 6, 2 }
};
int rows = input_matrix.length;
int column = input_matrix[0].length;
System.out.println("The matrix is defined as: ");
for (int i = 0; i < rows; i++) {
for (int j = 0; j < column; j++) {
System.out.print(input_matrix[i][j] + " ");
}
System.out.println();
}
if (rows != column) {
return;
} else {
for (int i = 0; i < rows; i++) {
for (int j = 0; j < column; j++) {
if (i > j) {
input_matrix[i][j] = 0;
}
}
}
System.out.println("\nThe upper triangular matrix is: ");
for (int i = 0; i < rows; i++) {
for (int j = 0; j < column; j++) {
System.out.print(input_matrix[i][j] + " ");
}
System.out.println();
}
}
}
}

## Output

The matrix is defined as:
2 1 4
1 2 3
3 6 2

The upper triangular matrix is:
2 1 4
0 2 3
0 0 2

## Example 2

Here, we encapsulate the operations into functions exhibiting object-oriented programming.

public class UpperTriangle {
public static void upper_triangular_matrix(int input_matrix[][]) {
int rows = input_matrix.length;
int column = input_matrix[0].length;
if (rows != column) {
return;
} else {
for (int i = 0; i < rows; i++) {
for (int j = 0; j < column; j++) {
if (i > j) {
input_matrix[i][j] = 0;
}
}
}
System.out.println("\nThe upper triangular matrix is: ");
for (int i = 0; i < rows; i++) {
for (int j = 0; j < column; j++) {
System.out.print(input_matrix[i][j] + " ");
}
System.out.println();
}
}
}
public static void main(String[] args) {
int input_matrix[][] = {
{ 2, 1, 4 },
{ 1, 2, 3 },
{ 3, 6, 2 }
};
int rows = input_matrix.length;
int column = input_matrix[0].length;
System.out.println("The matrix is defined as: ");
for (int i = 0; i < rows; i++) {
for (int j = 0; j < column; j++) {
System.out.print(input_matrix[i][j] + " ");
}
System.out.println();
}
upper_triangular_matrix(input_matrix);
}
}

## Output

The matrix is defined as:
2 1 4
1 2 3
3 6 2

The upper triangular matrix is:
2 1 4
0 2 3
0 0 2

Updated on: 29-Mar-2022

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