“…Similarly, if one instead uses the rotated stencil, that would require the knowledge of ( y + ) 4 0 , which is not available, either. Therefore, the only available option is to find (y ± ) 3 0 is by the MoC-pRK3 with the rotated stencil, as shown in Figure 11b and c. In this stencil, we already know the solution at nodes (n, m) = (1, 2), (2, 1), (3,2), and (4, 1). However, we do not know the solution y + at node (5,2), because this is precisely the solution that we need (y ± ) 3 0 for!…”