> On Oct 15, 2017, at 6:20 PM, zakaryah . <[email protected]> wrote: > > For finite difference methods, using a DMDA with DMDA_BOUNDARY_GHOSTED is > great for Dirichlet boundary conditions, because I can just set the Dirichlet > values on the ghost points, correct?
Yes, > It seems to me that the analogous method for Neumann conditions would be to > use a reflecting boundary condition, and if the Neumann values are nonzero, > these could be added to the constant vector. I am not sure what you mean by "added to the constant vector", what constant vector? > Is this correct? Is DMDA_BOUNDARY_MIRROR supposed to do this? Yes see http://scicomp.stackexchange.com/questions/5355/writing-the-poisson-equation-finite-difference-matrix-with-neumann-boundary-cond > Is it implemented yet, or are there plans to implement it soon? It is implemented for 2d; if you need 3d you can try to implement it yourself or ask us and we'll look and see how difficult it might be. > Otherwise, is there any way to efficiently implement Neumann conditions > besides branching with if statements? Yes, this stuff is here to some degree to eliminate all the horrible if checks in user code. Barry > Thanks in advance!
