On Fri, Jul 6, 2012 at 5:06 AM, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote:
> Here's the line in question (also see the immediately preceding code): > http://petsc.cs.iit.edu/petsc/petsc-dev/rev/0d4ccb990bb8#l1.127 > As long as we are fixing this, I would rather not repeat the prefix, since we will likely want to configure this differently than the block 0 solve. Is any thing wrong with schurprefix+"_sub" Matt > Dmitry. > > > ---------- Forwarded message ---------- > From: Dmitry Karpeev <karpeev at mcs.anl.gov> > Date: Fri, Jul 6, 2012 at 6:04 AM > Subject: Re: [petsc-dev] Problematic Merge of FieldSplit > To: For users of the development version of PETSc <petsc-dev at mcs.anl.gov> > > > I have the following problem with the prefix choice for the > MatSchurComplement KSP introduced in this changeset ( > http://petsc.cs.iit.edu/petsc/petsc-dev/rev/0d4ccb990bb8). > I'm talking about the "inner" KSP for A00, effecting inv(A00) in the > definition S = A11 - A10 inv(A00) A01. > We also have the "outer" inv(A00) KSP, which gets prefix "0". I > recently set the "inner" inv(A00) KSP > prefix to "0", simply by inheriting it from the "outer" solver. Now, it > is completely reasonable > to expect the inner and outer A00 KSPs to have different prefixes so that > they can be configured differently. > In fact, there was a recent petsc-users request related to this ( > http://lists.mcs.anl.gov/pipermail/petsc-users/2012-June/014005.html). > However, currently the inner A00 KSP inherits the prefix from the A11 KSP > corresponding to the "1" field. With this prefix choice > I end up configuring inv(A00) and inv(S) identically, which isn't what I > want at all. > I'm not sure what the right approach is, but the current one doesn't work > for me. > > Note also that if A00 is treated with a recursive split, there may be > numerous options for the A00 KSP. > Do we want to repeat them for the inner and outer KSPs, if we want to > configure them identically? > It's automatic, if the two A00 KSPs share a prefix. Again, this takes > away some flexibility, so maybe it's not the best solution, > but I think retaining a simple option for using identical configurations > is also highly desirable. > > Any ideas on how to handle this? > Dmitry. > > On Tue, Jun 26, 2012 at 6:13 AM, Matthew Knepley <knepley at gmail.com>wrote: > >> It turns out that 'hg rollback' during an 'hg rebase' does not do what I >> thought it did. I think >> everything is cleaned up with this push, but if you made FS changes in >> the past month, please >> check that it is doing what you want with prefixes, etc. >> >> Now, nested fieldsplits from the command line work, ala >> >> -ksp_type fgmres >> -pc_type fieldsplit -pc_fieldsplit_type additive >> -pc_fieldsplit_0_fields 0,1 >> -fieldsplit_0_pc_type fieldsplit >> -fieldsplit_0_pc_fieldsplit_type schur >> -fieldsplit_0_pc_fieldsplitschur_factorization_type full >> -fieldsplit_0_fieldsplit_velocity_ksp_type preonly >> -fieldsplit_0_fieldsplit_velocity_pc_type lu >> -fieldsplit_0_fieldsplit_pressure_ksp_rtol 1e-10 >> -fieldsplit_0_fieldsplit_pressure_pc_type jacobi >> -pc_fieldsplit_1_fields 2 >> -fieldsplit_temperature_ksp_type preonly >> -fieldsplit_temperature_pc_type lu >> >> A split with only one field gets the field name, and otherwise a split >> number. >> >> Matt >> >> -- >> What most experimenters take for granted before they begin their >> experiments is infinitely more interesting than any results to which their >> experiments lead. >> -- Norbert Wiener >> > > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20120706/a2077a8c/attachment.html>
