Thanks for your help! Going from individual blocks to a whole matrix makes perfect sense if the blocks are readily available or needed as fully functional matrices. Don't change that! Maybe add the opposite?
I'm surprised it's broken though: on this mailing list several petsc developers have stated on several occasions (and not just to me) things like "you should never have a matnest", "you should have a mat then change the type at runtime", "snes ex70 is not the intended use" and so on. I fully appreciate the benefit of having a format-independent assembly and switching mat type from aij to nest depending on the preconditioner. And given the manual and the statements on this list, I thought this would be standard practice and therefore thoroughly tested. But now I get the impression it has never worked... Chris > From: Matthew Knepley <knep...@gmail.com> > Sent: Tuesday, August 02, 2016 12:28 AM > To: Klaij, Christiaan > Cc: petsc-users@mcs.anl.gov; Jed Brown > Subject: Re: [petsc-users] block matrix without MatCreateNest > > On Mon, Aug 1, 2016 at 9:36 AM, Klaij, Christiaan <c.kl...@marin.nl> wrote: > > Matt, > > > 1) great! > > > 2) ??? that's precisely why I paste the output of "cat mattry.F90" in the > emails, so you have a small example that produces the errors I mention. Now > I'm also attaching it to this email. > > Okay, I have gone through it. You are correct that it is completely broken. > > The way that MatNest currently works is that it trys to use L2G mappings from > individual blocks > and then builds a composite L2G map for the whole matrix. This is obviously > incompatible with > the primary use case, and should be changed to break up the full L2G into one > for each block. > > Jed, can you fix this? I am not sure I know enough about how Nest works. > > Matt > > Thanks, > > Chris dr. ir. Christiaan Klaij | CFD Researcher | Research & Development MARIN | T +31 317 49 33 44 | c.kl...@marin.nl<mailto:c.kl...@marin.nl> | www.marin.nl<http://www.marin.nl> [LinkedIn]<https://www.linkedin.com/company/marin> [YouTube] <http://www.youtube.com/marinmultimedia> [Twitter] <https://twitter.com/MARIN_nieuws> [Facebook] <https://www.facebook.com/marin.wageningen> MARIN news: Ship design in EU project Holiship<http://www.marin.nl/web/News/News-items/Ship-design-in-EU-project-Holiship.htm>
