<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On May 3, 2022, at 12:37 PM, Mark Adams <<a href="mailto:mfadams@lbl.gov" class="">mfadams@lbl.gov</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><div class=""><br class=""></div><blockquote type="cite" class=""><div class=""><div style="overflow-wrap: break-word;" class=""><div class="">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?</div></div></div></blockquote><div class=""><br class=""></div><div class="">That was always the case before, you may have misinterpreted the meaning of a Mat block size?</div></div></div></blockquote><div class=""><br class=""></div><div class="">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.</div><div class="">At least that is my understanding.</div><div class="">There is a CI test that has sparse blocks and I ran into this issue with GAMG optimizations.</div><div class="">(I had to add complicated code that Pierre actually found a bug in.)</div><div class=""><br class=""></div><div class="">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.</div><div class=""><br class=""></div><div class="">I did not follow this whole thread, but Randall could you change your code to add dense blocks or not use block size?</div><div class="">Sorry, but I just don't think we should support this (Pierre seems to think that we do not) and we should "depreciate" this.</div><div class="">This needs to be discussed of course.</div><div class=""><br class=""></div><div class="">Mark</div></div></div>
</div></blockquote></div><br class=""><div class="">Hi Mark and Pierre,</div><div class=""><br class=""></div><div class="">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.</div><div class=""><br class=""></div><div class="">But as long as the matrix entries are set correctly, block size doesn’t really matter.</div><div class=""><br class=""></div><div class="">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).</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Thanks for the help and the clarifications,</div><div class=""><br class=""></div><div class="">Randy</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div></body></html>