<html><head><meta http-equiv="content-type" content="text/html; charset=us-ascii"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div><br></div> 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.<div><br></div><div> Barry</div><div><br><div><br><blockquote type="cite"><div>On Dec 1, 2022, at 3:43 PM, Alfredo J Duarte Gomez <aduarteg@utexas.edu> wrote:</div><br class="Apple-interchange-newline"><div><div dir="ltr">Good morning,<div><br></div><div>Good afternoon,</div><div><br></div><div>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)</div><div><br></div><div>I have used the default version of algebraic multigrid (that is -pc_gamg_type agg) very easily.</div><div><br></div><div>When I try to use
-pc_gamg_type geo, it returns an error.</div><div><br></div><div>What additional lines of code do I have to add to use the geo option? </div><div><br></div><div>Or does this require some sort of fast remeshing routine, given that I am using curvilinear grids?</div><div><br></div><div>Thank you and have a good day.</div><div><br></div><div>-Alfredo</div><div><div><br></div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><font face="arial, sans-serif">Alfredo Duarte</font><div><font face="arial, sans-serif">Graduate Research Assistant</font></div><div><font face="arial, sans-serif">The University of Texas at Austin</font></div></div></div></div></div></div></div>
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