C Exercises: Display the lower triangular of a given matrix

C Array: Exercise-26 with Solution

Write a program in C to print or display the lower triangular of a given matrix.

The task is to write a C program that prints the lower triangular matrix of a given square matrix. The program prompts the user to input the size of the matrix and its elements, then it displays the original matrix. After that, it modifies the matrix to show only its lower triangular part (where elements above the main diagonal are set to zero) and prints this modified matrix as output.

Visual Presentation:

Sample Solution:

C Code:

#include <stdio.h>

int main() {
    int arr1[10][10], i, j, n;
    float determinant = 0;

    // Display the purpose of the program
    printf("\n\nDisplay the lower triangular of a given matrix :\n");
    printf("----------------------------------------------------\n");

    // Input the size of the square matrix
    printf("Input the size of the square matrix : ");
    scanf("%d", &n);

    // Input elements into the matrix
    printf("Input elements in the matrix :\n");
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            printf("element - [%d],[%d] : ", i, j);
            scanf("%d", &arr1[i][j]);
        }
    }

    // Display the original matrix
    printf("The matrix is :\n");
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            printf("% 4d", arr1[i][j]);
        }
        printf("\n");
    }

    // Display lower triangular matrix by setting upper triangular elements to zero
    printf("\nSetting zero in lower triangular matrix\n");
    for (i = 0; i < n; i++) {
        printf("\n");
        for (j = 0; j < n; j++) {
            if (i <= j) {
                printf("% 4d", arr1[i][j]); // Print the original elements if i <= j (lower triangular)
            } else {
                printf("% 4d", 0); // Print zero if i > j (upper triangular)
            }
        }
    }
    printf("\n\n");

    return 0;
}

Sample Output:

Display the lower triangular of a given matrix :                                                              
----------------------------------------------------                                                          
Input the size of the square matrix : 3                                                                       
Input elements in the first matrix :                                                                          
element - [0],[0] : 1                                                                                         
element - [0],[1] : 2                                                                                         
element - [0],[2] : 3                                                                                         
element - [1],[0] : 4                                                                                         
element - [1],[1] : 5                                                                                         
element - [1],[2] : 6                                                                                         
element - [2],[0] : 7                                                                                         
element - [2],[1] : 8                                                                                         
element - [2],[2] : 9                                                                                         
The matrix is :                                                                                               
   1   2   3                                                                                                  
   4   5   6                                                                                                  
   7   8   9 
Setting zero in lower triangular matrix                                                                       
                                                                                                              
   1   2   3                                                                                                  
   0   5   6                                                                                                  
   0   0   9                                     

Flowchart:

C Programming Code Editor:

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