A **lower triangular matrix** is a special type of square matrix where all the entries above the main diagonal are zero. This means that if you have a matrix \( A \), it is lower triangular if \( A[i][j] = 0 \) for all indices \( i < j \). The main diagonal elements can be any value (including zero), and the elements below the diagonal can also be any value.
### Definition
For a square matrix \( A \) of size \( n \times n \):
- \( A[i][j] = 0 \)