On Tue, May 14, 2013 at 2:35 PM, Isik Ali Ozcer <isik.ozcer at mail.mcgill.ca>wrote:
> Hi All, > > Regarding ILU convergence at subdomain boundaries, I need to add to my > colleague's message that we followed a very basic tutorial that shows > matrix and rhs assembly, preconditioner and solver setup, and finally a > KSPsolve. We did not prepare any application ordering information or index > sets. I am not sure if Petsc in our implementation has all the info it > needs to perform proper overlapping operations with ASM. Do we need to > worry about setting up AO and IS contexts before attempting KSPsolve with > ASM and ILU? > No the matrix is enough. Matt > Thanks a lot and have a great day, > > Isik > petsc-newb > > > > -------- Original Message -------- > Subject: Re: [petsc-users] Question on asm > Date: Tue, 14 May 2013 13:03:38 -0500 > From: Jed Brown <jedbrown at mcs.anl.gov> > To: Konstantinos Kontzialis <ckontzialis at lycos.com>, > petsc-users at mcs.anl.gov > > > > Konstantinos Kontzialis <ckontzialis at lycos.com> writes: > > > Dear all, > > > > I am using asm as a preconditioner for solving the Navier Stokes > > equations. When using ILU as the subdomain preconditioner, I notice > > convergence problems in the partition boundaries. > > I.e., it converges slowly there? That is natural because the > preconditioner is more accurate in the interior of subdomains. > > > This does not happen with the Jacobi preconditioner. > > Naturally, because Jacobi is identical regardless of the partition. > > > Do I need to provide any connectivity, node mapping, and/or overlap > > information to Petsc before calling KSPsolve? > > No, the matrix is enough. > > -- 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/20130514/fc9d7048/attachment.html>
