These first order hyperbolic systems are the same as those in Section 3. If the one way wave equation is applied each time step, then any error from the previous time step can be computed using Equation 61. This error can be corrected in the current application of the boundary condition. This is Equation 62, which is for the left side of the model as shown in Figure 15.

Figure 15: Model Boundary Node Stencil, Left Side.