Write a C program to read elements in a matrix and find sum of lower triangular matrix. How to find sum of lower triangular matrix in C.

If the elements of matrix are:

1 0 0

4 5 0

7 8 9

Sum of lower triangular matrix = 19

For any matrix

sum = sum +

Happy coding ;)

**Example:**If the elements of matrix are:

1 0 0

4 5 0

7 8 9

Sum of lower triangular matrix = 19

### Required knowledge:

Basic C programming, For loop, Array, Matrix#### Lower triangular matrix

Lower triangular matrix is a special square matrix whole all elements above the main diagonal is zero.### Algorithm to find sum of lower triangular matrix:

Lower triangular matrix elements is shown in the below image. We need to find sum of all elements in the red triangular area.For any matrix

**A**sum of lower triangular matrix elements can be defined as:sum = sum +

**A**_{ij}(Where*j < i*).### Program:

/** * C program to find sum of lower triangular matrix */ #include <stdio.h> int main() { int A[3][3]; int row, col, sum = 0; /* * Reads elements in matrix from user */ printf("Enter elements in matrix of size 3x3: \n"); for(row=0; row<3; row++) { for(col=0; col<3; col++) { scanf("%d", &A[row][col]); } } /* * Finds sum of lower triangular matrix */ for(row=0; row<3; row++) { for(col=0; col<3; col++) { if(col<row) { sum += A[row][col]; } } } printf("Sum of lower triangular matrix = %d", sum); return 0; }

Output

Enter elements in matrix of size 3x3:

1 0 0

4 5 0

7 8 9

Sum of lower triangular matrix = 19

1 0 0

4 5 0

7 8 9

Sum of lower triangular matrix = 19

Happy coding ;)

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