Can you use the debugger to get a stack trace? Matt
On Tue, Nov 24, 2009 at 10:46 AM, francois pacull <fpacull at fluorem.com>wrote: > Dear PETSc team, > > I am having a little bit of trouble with the Schur option of PCFieldSplit: > I would like to apply some special treatments respectively to the five first > and the two last equations over seven for each grid node of a CFD linear > system... > > In the present case, the KSP is "gmres" (or "fgmres" if the PC is > changing), the PC is "asm" (the subdomain IS is defined with > PCASMSetLocalSubdomains in order to always include all the fields associated > to the grid points of the overlap), the SUBKSP is "preonly" and the SUBPC is > "fieldsplit". > > So far the FieldSplit options PC_COMPOSITE_ADDITIVE and > PC_COMPOSITE_MULTIPLICATIVE work well with fieldsplit_0 and fieldsplit_1 set > to KSPPREONLY and PCILU in the following way: > > PCFieldSplitGetSubKSP(SubPC,number_of_split,&FieldSplitKSP); > ... [for the fields 0,1,2,3,4 (fieldsplit_0)] > KSPSetType(FieldSplitKSP[0],KSPPREONLY); > KSPGetPC(FieldSplitKSP[0],&FieldSplitPC0); > PCSetType(FieldSplitPC0,PCILU); > ... [for the fields 5 and 6 (fieldsplit_1)] > KSPSetType(FieldSplitKSP[1],KSPPREONLY); > KSPGetPC(FieldSplitKSP[1],&FieldSplitPC1); > PCSetType(FieldSplitPC1,PCILU); > ... > > They also work well when I set the FieldSplitKSP[0] and/or FieldSplitKSP[1] > to KSPGMRES. However, I always get a segmentation violation when I try to > use the FieldSplit option PC_COMPOSITE_SCHUR... I guess that I am missing > something: is there more options to set in this Schur case? > So far I did not turn on the Schur complement preconditioner option: > PCFieldSplitSchurPrecondition(subpc,PETSC_FALSE); > Is there a book or article describing the methods implemented in this > FieldSplit option? > > The version is petsc-3.0.0-p7... > > Thank you for your help, > Regards, > francois pacull. > > -- 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-users/attachments/20091124/550e0808/attachment.htm>
