C Program to Find Sum of All Lower Triangular Matrix Elements

  • Write a C program to find the sum of all elements in lower triangular matrix
  • C program to add all elements of lower triangular matrix.

Required Knowledge

The main diagonal of a square matrix divides it into two sections, one above the diagonal and the other one is below the diagonal. We have to find the sum of all elements in lower triangular matrix.
A matrix element matrix[i][j] is part of lower triangular matrix if i > j.

C Program to find sum of lower triangular elements of matrix

#include <stdio.h>
#include <conio.h>
 
int main(){
    int rows, cols, size, row, col, sum=0;
    int inputMatrix[50][50];
    
    printf("Enter size square matrix\n");
    scanf("%d", &size);
    rows = cols = size;
     
    printf("Enter Matrix of size %dX%d\n", rows, cols);
    /*  Input matrix*/
    for(row = 0; row < rows; row++){
        for(col = 0; col < cols; col++){
            scanf("%d", &inputMatrix[row][col]);
        }
    }
    /* 
     *  Find sum of lower Triangular Elements 
     */
    for(row = 0; row < rows; row++){
        for(col = 0; col < cols; col++){
            if(row > col){
                /* Lower triangular matrix element*/
                sum += inputMatrix[row][col];
            }
        }
    }

    printf("Sum of Lower triangular Matrix Elements\n%d", sum);
    
    getch();
    return 0;
}
Output
Enter size square matrix
3
Enter Matrix of size 3X3
1 2 3
4 5 6
7 8 9
Sum of Lower triangular Matrix Elements
19

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