Finite Difference Schemes for the (3+1)D Wave Equation

We now look at several difference schemes which solve the wave equation in (3+1)D, in particular schemes which operate on a rectilinear grid; all the schemes which have appeared in the DWN literature are of this type. We will pay special attention to the interpolated scheme, for which the requirements for stability and passivity become even more distinct than they were in the (2+1)D case (see §3.2).