Hi Hong, Thanks for your help. I am testing if I can use MUMPS block low rank factors as a preconditioner for QMR in MUMPS framework. I would like to ask one more question. STRUMPACK ( http://portal.nersc.gov/project/sparse/strumpack/) also supports low rank approximation. Can PETSC also allow users to use the approximate factors as a preconditioner in PETSC-QMR?
Best, Evan On Tue, Oct 3, 2017 at 8:34 AM, Hong <hzh...@mcs.anl.gov> wrote: > Evan, > ICNTL(35) and CNTL(7) are added to petsc-mumps interface in branch > hzhang/update-mumps-5.1.1-cntl > > You may give it a try. Once it passes our regression tests, I'll merge it > to petsc master branch. > > Hong > > > On Sun, Sep 24, 2017 at 8:08 PM, Hong <hzh...@mcs.anl.gov> wrote: > >> I'll check it. >> Hong >> >> On Sun, Sep 24, 2017 at 3:42 PM, Evan Um <eva...@gmail.com> wrote: >> >>> Hi Barry, >>> >>> Thanks for your comments. To activate block low rank (BLR) approximation >>> in MUMPS version 5.1.1, a user needs to turn on the functionality (i.e. >>> ICNTL(35)=1) and specify the tolerance value (e.g. CNTL(7)=1e-4). In PETSC, >>> I think that we can set up ICNTL and CNTL parameters for MUMPS. I was >>> wondering if we can still use BLR approximation for a preconditioner for >>> Krylov solvers. >>> >>> Best, >>> Evan >>> >>> >>> On Sat, Sep 23, 2017 at 6:45 PM, Barry Smith <bsm...@mcs.anl.gov> wrote: >>> >>>> >>>> > On Sep 23, 2017, at 8:38 PM, Evan Um <eva...@gmail.com> wrote: >>>> > >>>> > Dear PETSC Users, >>>> > >>>> > My system matrix comes from finite element modeling and is complex >>>> and unstructured. Its typical size is a few millions-by a few millions. I >>>> wondering if I can use MUMPS parallel direct solver as a preconditioner in >>>> PETSC. For example, I want to pass factored matrices to Krylov iterative >>>> solvers such as QMR. Is there any PETSC+MUMPS example code for the purpose? >>>> >>>> You don't pass factored matrices you just pass the original matrix >>>> and use -pc_type lu -pc_factor_mat_solver_package mumps >>>> >>>> > Can PETSC call the latest MUMPS that supports block low rank >>>> approximation? >>>> >>>> No, send us info on it and we'll see if we can add an interface >>>> >>>> >>>> > >>>> > In advance, thank you very much for your comments. >>>> > >>>> > Best, >>>> > Evan >>>> > >>>> > >>>> > >>>> > >>>> > >>>> >>>> >>> >> >