Hi guys,
I have a custom multigrid preconditioner that uses Galerkin coarsening
for the staggered grid finite difference. Now I want to replace a few
top level operators with the matrix-free shell matrices.
Here is my plan:
1. Set PC_MG_GALERKIN_NONE
2. Call PCMGSetRestriction and PCMGSetInterpolation on all levels as I
do it already
3. Use a combination of PCMGGetSmoother and KSPSetOperators to
communicate my operators with PCMG
a. On the top levels just set the shell matrices minimalistically
equipped with MATOP_GET_DIAGONAL and MATOP_MULT.
b. On the bottom levels generate the operators by explicitly
calling MatMatMatMult (R is not the same as P in my case).
Use MAT_INITIAL_MATRIX for the first time
Use MAT_REUSE_MATRIX for the subsequent calls
Is this a proper way to do it, or there is something wrong?
If I want the restriction/interpolation matrices to be matrix-free on
the top levels as well, I would need to set MATOP_MULT_ADD for them. Is
this enough, or do I need something else?
Thanks!
Anton
