# Forward substitution

The recursion to solve a nonsingular lower triangular system, $LaTeX: Lx=b$. It starts with $LaTeX: x_1 = b_1 / L_{1,1}$, then
$LaTeX: x_j = \left( b_j - \sum_{i < j} L_{i, j} x_i \right) / L_{j,j}.$
for $LaTeX: j=2,...,n$.