Display upper and lower triangle of the matrix

Posted on Apr 25, 2020

C program to display upper and lower triangle of the matrix.

Lower Triangular Matrix
A square matrix is called lower triangular if all the entries above the main diagonal are zero.

Upper Triangular Matrix
A square matrix is called upper triangular if all the entries below the main diagonal are zero.

Program

#include<stdio.h>
#include<conio.h>
#define MAX 10

void main()
{
	int mat[MAX][MAX];
    int row, col;
    int i, j;

    printf("Enter the number of rows or columns of the square matrix\t:");
    scanf("%d",&row);
    col = row;

    printf("Enter the elements\n");
    for(i=0;i<row;i++)
    {
        for(j=0;j<col;j++)
        {
            printf("Element [%d][%d]\t:",i,j);
            scanf("%d",&mat[i][j]);
        }
    }

    printf("\n\nMatrix entered is\n");
    for(i=0;i<row;i++)
    {
        for(j=0;j<col;j++)
        {
            printf("%d\t",mat[i][j]);
        }
        printf("\n");
    }

    printf("\nLower Triangular Matrix\n");
    for(i=0;i<row;i++)
    {
        for(j=0;j<col;j++)
        {
            if(i<j)
            {
                printf("0\t");
            }
            else
            {
                printf("%d\t",mat[i][j]);
            }
        }
        printf("\n");
    }

    printf("\nUpper Triangular Matrix\n");
    for(i=0;i<row;i++)
    {
        for(j=0;j<col;j++)
        {
            if(i>j)
            {
                printf("0\t");
            }
            else
            {
                printf("%d\t",mat[i][j]);
            }
        }
        printf("\n");
    }

    getch();
}

Output

Enter the number of rows or columns of the square matrix        :4
Enter the elements
Element [0][0]  :1
Element [0][1]  :2
Element [0][2]  :3
Element [0][3]  :4
Element [1][0]  :5
Element [1][1]  :6
Element [1][2]  :7
Element [1][3]  :8
Element [2][0]  :9
Element [2][1]  :10
Element [2][2]  :11
Element [2][3]  :12
Element [3][0]  :13
Element [3][1]  :14
Element [3][2]  :15
Element [3][3]  :16


Matrix entered is
1       2       3       4
5       6       7       8
9       10      11      12
13      14      15      16

Lower Triangular Matrix
1       0       0       0
5       6       0       0
9       10      11      0
13      14      15      16

Upper Triangular Matrix
1       2       3       4
0       6       7       8
0       0       11      12
0       0       0       16