Forwarding this to people who might have a clue. On Sep 17, 2013, at 5:09 PM, Jungho Lee <[email protected]> wrote:
> I'm looking into the 6*6 grid case, with dof=3, so the system matrix size is > 108*108. > > 1) It turns out that using > > -pc_type gamg -pc_gamg_type agg > > results in two levels with the coarse problem being 13*13. Wouldn't it be > natural for the coarse problem to be of size that's an integer multiple of 3, > though? It turned out that KSP->mat->rmap->bs = 1 for the finest level > matrix, so I added > > MatSetBlockSize(user.M,3) > > in the main code, but it seems like this information somehow gets lost by the > time lower-level functions (such as graph, coarsen, createlevel...) in > gamg.c, agg.c, tools.c, etc., are called. > > 2) For the specific set of parameters I'm using for testing purposes, the > smallest nonzero entry of the finest level matrix is of order e-7. For the > coarse level matrix (size 13*13), whose entries are determined by MatPtAP > called in createlevel (in gamg.c), the smallest nonzero entry is of order > e-24 - this jumped out at me as a potential sign of something wrong. > > Thoughts? > > Thanks, > Jungho
