\[\begin{bmatrix}w(z_{j+1})\\
w^{\prime}(z_{j+1})\end{bmatrix}=\mathbf{A}(\tau_{j},z_{j})\begin{bmatrix}w(z_%
{j})\\
w^{\prime}(z_{j})\end{bmatrix}+\mathbf{b}(\tau_{j},z_{j}),\]