On Dec 29, 2011, at 12:51 PM, Dave Nystrom wrote: > Jed Brown writes: >> On Thu, Dec 29, 2011 at 11:15, Dave Nystrom <dnystrom1 at comcast.net> wrote: >> >>> I have tried out -ksp_type cg -pc_type gamg -pc_gamg_type sa on my problem >>> and am encouraged enough with the results that I would like to try taking >>> the >>> next step with using gamg. Could you provide some advice on how to do >>> that? >>> I'm not sure how to provide the null space info you say is important. >>> >> >> Are you solving a scalar or vector problem? > > Both although the most challenging problem right now is one for a Hall matrix > system that is block banded with 2x2 blocks. Right now, I am just inputting > the matrix into a petsc seqaij matrix.
Thats fine, actually require. Just call this: ierr = MatSetBlockSize(Amat,3); CHKERRQ(ierr); > I guess I need to put it into a petsc > block matrix but have not yet attempted to do that. I'm not sure how much > work is involved - I need to read the section in the users manual on that. > > Anyway, I have 5 scalar systems and on vector system with 2x2 blocks. I am > interested in applying gamg to all of them to see how well it works. >
