C Program to find Lower Triangle Matrix

How to write a C Program to find Lower Triangle Matrix with example?. A Lower triangle Matrix is a square matrix where elements above the main diagonal are zeros.

C Program to find Lower Triangle Matrix Example

This program allows the user to enter the number of rows and columns of a Matrix. Next, this C program will find the Lower triangle of this matrix using For Loop.

/* C Program to find Lower Triangle Matrix */
 
#include<stdio.h>
 
int main()
{
 	int i, j, rows, columns, a[10][10];
  
 	printf("\n Please Enter Number of rows and columns  :  ");
 	scanf("%d %d", &i, &j);
 
 	printf("\n Please Enter the Matrix Elements \n");
 	for(rows = 0; rows < i; rows++)
  	{
   		for(columns = 0;columns < j;columns++)
    	{
      		scanf("%d", &a[rows][columns]);
    	}
  	}
     
 	for(rows = 0; rows < i; rows++)
  	{
  		printf("\n");
   		for(columns = 0; columns < j; columns++)
    	{
    		if(rows >= columns)
    		{
    			printf("%d ", a[rows][columns]);
			}
			else
			{
				printf("0  ");
			}
   	 	}
  	}
  	
 	return 0;
}

OUTPUT

ANALYSIS

In this C Program to find Lower Triangle Matrix, We declared single Two dimensional arrays Multiplication of size of 10 * 10.

Below statements asks the User to enter the Matrix size (Number of rows and columns. For instance 2 Rows, 2 Columns = a[2][2] )

printf("\n Please Enter Number of rows and columns  :  ");
scanf("%d %d", &i, &j);

Next, we used for loop to iterate every cell present in a[2][2] matrix. Conditions inside the for loops ((rows < i) and (columns < j)) will ensure the compiler, not to exceed the matrix limit. Otherwise, the matrix will overflow

scanf statement inside the for loop will store the user entered values in every individual array element such as a[0][0], a[0][1], …..

for(rows = 0; rows < i; rows++).
{
  for(columns = 0; columns < j; columns++)
   {
     scanf("%d", &a[rows][columns]);
   }
}

In the next line, We have one more for loop to find Lower Triangle of a Matrix

for(rows = 0; rows < i; rows++)
{
	printf("\n");
	for(columns = 0; columns < j; columns++)
    	{
    		if(rows >= columns)
    		{
    			printf("%d ", a[rows][columns]);
		}
		else
		{
			printf("0  ");
		}
 	}
}

User inserted values for C Program to find Lower Triangle Matrix are: a[2][2] = {{10, 20}, { 30, 40}}

Row First Iteration: for(rows = 0; rows < 2; 0++)
The condition (0 < 2) is True.

Column First Iteration: for(columns = 0; 0 < 2; 0++)
The condition (columns < 2) is True. So, it will start executing the statements inside the loop

if(rows >= columns) => if(0 >= 0) – This condition is True. So, it will print a[0][0] = 10

Column Second Iteration: for(columns = 1; 1 < 2; 1++)
The condition (columns < 2) is True.

if(rows >= columns)=> if(0 >= 1) – This condition is False. So, it will print 0

Column Third Iteration: for(columns = 2; 2 < 2; 2++)
The condition (columns < 2) is False. So it will exit from the loop.

Next, rows value will increment to 1.

Row Second Iteration: for(rows = 1; rows < 2; 1++)
The condition (1 < 2) is True.

Column First Iteration: for(columns = 0; 0 < 2; 0++)
The condition (columns < 2) is True. So, it will start executing the statements inside the loop

if(rows >= columns) => if(1 >= 0) – This condition is False. So, it will print a[1][0] = 30

Column Second Iteration: for(columns = 1; 1 < 2; 1++)
The condition (columns < 2) is True.

if(rows >= columns) => if(1 >= 1) – condition is True. So, it will print a[1][1] = 40

Column Third Iteration: for(columns = 2; 2 < 2; 2++)
The condition (columns < 2) is False. So it will exit from the loop.

Next, rows value will increment to 1. After the increment, the condition inside the first for loop (rows < 2) will fail. So it will exit from the loop.

Let me try the same with the 3 * 3 matrix