> On May 3, 2022, at 12:37 PM, Mark Adams <[email protected]> wrote: > > >> Are you saying that now you have to explicitly set each 3x3 dense block, >> even if they are not used and that was not the case before? > > That was always the case before, you may have misinterpreted the meaning of a > Mat block size? > > Actually block size is really more of a hint in that you don't have to set > 3x3 dense blocks and thus any AIJ matrix can have any block size essentially. > At least that is my understanding. > There is a CI test that has sparse blocks and I ran into this issue with GAMG > optimizations. > (I had to add complicated code that Pierre actually found a bug in.) > > I don't know what changed in PETSc to make ASM fail for you, but if > MatConvert and ASM fail then PETSc is broken and always has been. > > I did not follow this whole thread, but Randall could you change your code to > add dense blocks or not use block size? > Sorry, but I just don't think we should support this (Pierre seems to think > that we do not) and we should "depreciate" this. > This needs to be discussed of course. > > Mark
Hi Mark and Pierre, You are correct that it is not necessary to use the block size. I had done that many many years ago because for some reason I thought it was necessary when creating a matrix for a 3D grid with more than 1 degree of freedom per node. But as long as the matrix entries are set correctly, block size doesn’t really matter. I think part of the issue in my situation is that there are parts of the matrix where not all 3x3 dense blocks are set due to representing a staggered grid system using a 3D DMDA (but like I say this was done many years before DMStag was developed). Thanks for the help and the clarifications, Randy
