I don't think you want to use -pc_type gamg if you want to use geometric multigrid. You can can use -pc_type mg and the DMDA. The only thing I think you need to change from the default use of DMDA and -pc_type mg is to provide custom code that computes the interpolation between levels to take into account the curvilinear grids. Barry

On Dec 1, 2022, at 3:43 PM, Alfredo J Duarte Gomez <[email protected]> wrote:

Good morning,

Good afternoon,

I am testing the performance of some preconditioners on a problem I have and I wanted to try geometric multigrid. I am using a DMDA object and respective matrices (the mesh is structured, but not rectangular, it is curvilinear)

I have used the default version of algebraic multigrid (that is -pc_gamg_type agg) very easily.

When I try to use -pc_gamg_type geo, it returns an error.

What additional lines of code do I have to add to use the geo option?

Or does this require some sort of fast remeshing routine, given that I am using curvilinear grids?

Thank you and have a good day.

-Alfredo

-- Alfredo Duarte Graduate Research Assistant The University of Texas at Austin