question on DMMG

Barry Smith bsmith at
Tue Oct 10 14:53:04 CDT 2006


     Take a look at src/ksp/ksp/examples/tutorials and

    You should do it all with a DMMG and then it should be
pretty easy.


Note also: if you do not want to compute coarse matrices
you can use DMMGSetGalerkin() or -dmmg_galerkin and have
PETSc compute them.

On Tue, 10 Oct 2006, Randall Mackie wrote:

> I'm interested in trying to use multi-grid techniques to solve my problem,
> but it's unclear to me how to define the right-hand side and system matrix
> for my case where the grids are not uniform (ie, the grid lengths x,y,z are
> variable, and the grid properties are variable).
> Right now I'm solving my equations using a DA. So, on the finest scale I know
> how to compute the RHS and the Jacobian. It's unclear to me how PETSc
> does the multi-gridding, and therefore how I would write my code.
> Any pointers would be appreciated.
> Thanks, Randy

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