## Q. Write a program to print Lower triangular matrix of an array.

Lower triangular matrix :-A square matrix is called lower triangular if all the entries above the main diagonal are zero.
For Example :-
Input = matrix[3][3] =
{1 2 3
4 5 6
7 8 9}

Output = Lower :
1 0 0
4 5 0
7 8 9

## Lower Triangular Matrix Algorithm

START
Step 1 → Find the Index position of row and column.
Step 2 → If column position is greater than row position, then make that position 0.
STOP

# Lower Triangular Matrix Program

• C
• C++
• Java
• Python
• C#
• PHP
• #include <stdio.h>
int main() {
int rows=3, cols=3, i, j, matrix[3][3]={1,2,3,4,5,6,7,8,9};
printf("The Lower Triangular Matrix is: ");
for(i = 0; i < rows; i++){
printf("\n");
for(j = 0; j < cols; j++){
if(i >= j){
printf("%d\t ", matrix[i][j]);
}
else{
printf("0");
printf("\t");
}
}
}
return 0;
}

#include <iostream>
using namespace std;
// lower triangular matrix
void lower(int matrix[3][3], int row, int col)
{
int i, j;
for (i = 0; i < row; i++)
{
for (j = 0; j < col; j++)
{
if (i < j)
{
cout << "0" << " ";
}
else
cout << matrix[i][j] << " ";
}
cout << endl;
}
}
// Driver Code
int main()
{
int matrix[3][3] = {{1, 2, 3},
{4, 5, 6},
{7, 8, 9}};
int row = 3, col = 3;
cout << "The Lower Triangular Matrix is: \n";
lower(matrix, row, col);
return 0;
}

class LFC
{
// method to form lower
// triangular matrix
static void lower(int matrix[][],
int row, int col)
{
int i, j;
for (i = 0; i < row; i++)
{
for (j = 0; j < col; j++)
{
if (i < j)
{
System.out.print("0" + " ");
}
else
System.out.print(matrix[i][j] + " ");
}
System.out.println();
}
}
public static void main(String args[])
{
int matrix[][] = {{1, 2, 3},
{4, 5, 6},
{7, 8, 9}};
int row = 3, col = 3;
System.out.println("The Lower Triangular Matrix is: ");
lower(matrix, row, col);
}
}

def lower(matrix, row, col):
for i in range(0, row):
for j in range(0, col):
if (i < j):
print("0", end = " ");
else:
print(matrix[i][j],
end = " " );
print(" ");
matrix = [[1, 2, 3],
[4, 5, 6],
[7, 8, 9]];
row = 3;
col = 3;
print("The Lower Triangular Matrix is: ");
lower(matrix, row, col);

using System;
class LFC
{
// method to form lower
// triangular matrix
static void lower(int [,]matrix,
int row, int col)
{
int i, j;
for (i = 0; i < row; i++)
{
for (j = 0; j < col; j++)
{
if (i < j)
{
Console.Write("0" + " ");
}
else
Console.Write(matrix[i, j] + " ");
}
Console.WriteLine();
}
}
static public void Main ()
{
int [,]matrix = {{1, 2, 3},
{4, 5, 6},
{7, 8, 9}};
int row = 3, col = 3;
Console.WriteLine("The Lower Triangular Matrix is: ");
lower(matrix, row, col);
}
}

// Function to form
// lower triangular matrix
function lower(\$matrix, \$row, \$col)
{
\$i; \$j;
for (\$i = 0; \$i < \$row; \$i++)
{
for (\$j = 0; \$j < \$col; \$j++)
{
if (\$i < \$j)
{
echo "0" , " ";
}
else
echo \$matrix[\$i][\$j] , " ";
}
echo "\n";
}
}
\$matrix = array (array (1, 2, 3),
array (4, 5, 6),
array (7, 8, 9));
\$row = 3; \$col = 3;
echo "The Lower Triangular Matrix is: \n";
lower(\$matrix, \$row, \$col);

#include <stdio.h>
int main() {
int rows=3, cols=3, i, j, matrix[3][3]={1,2,3,4,5,6,7,8,9};
printf("\n The Lower Triangular Matrix is: ");
for(i = 0; i < rows; i++){
printf("\n");
for(j = 0; j < cols; j++){
if(i >= j){
printf("%d\t ", matrix[i][j]);
}
else{
printf("0");
printf("\t");
}
}
}
return 0;
}

#### Output

The Lower Triangular Matrix is:
1  0  0
4  5  0
7  8  9

## Recommended Programs

Program to print upper triangular matrix.

Program to print half pyramid pattern.