Hi, sorry if this is an obvious question, but i don't know how to use
the ghost nodes with a DMPlex.
The procedure i do is as follow :
1) create the DMPlex
2) distribute it
3) Create the Matrix and associated vectors with DMCreateMatrix,
DMCreateGlobalVector and DMCreateLocalVector
4) In each cells, compute the different integrals (FEM code)
I know the location of the ghost points, as the global index is negative
(and the global index is -(i+1) using the global PetscSection).
(I didn't use DMPlexConstructGhostCells, as i understood that is should
be used for flux calculations on faces for FV methods).
I would like to update the contributions of those ghost nodes, where the
vertex actually is (in a different processor).
So far, i used VecSetValues with the local indexes of the local vector.
Then i used DMLocalToGlobalBegin in order to update them. It's working fine.
I tried MatSetValues on the global Matrix with the global indexes. It
seems to work.
However, maybe i'm doing it the wrong way, with a lot of communications.
Is it a scalable way the handle them ? How should i do it ?
If i can have a starting point, it would be great !
Any help would be greatly appreciated!
Regards,
Yann
