$$ \left( \begin{array}{ccccc} b_0 & c_0 & & & \\ a_0 & b_1 & c_1 & & \\ & & \ddots & & \\ & & a_{m-3} & b_{m-2} & c_{m-2} \\ & & & a_{m-2} & b_{m-1} \end{array} \right) \left( \begin{array}{c} x_0 \\ x_1 \\ \vdots \\ x_{m-2} \\ x_{m-1} \end{array} \right)=\left( \begin{array}{c} f_0 \\ f_1 \\ \vdots \\ f_{m-2} \\ f_{m-1} \\ \end{array} \right) $$