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.
