Here is the C program to find the sum of all elements in lower triangular matrix. 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.

#### Required Knowledge

## C Program to find sum of lower triangular elements of matrix

#include <stdio.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); for(row = 0; row < rows; row++){ for(col = 0; col < cols; col++){ scanf("%d", &inputMatrix[row][col]); } } 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); 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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