[petsc-users] Block ILU with AIJ matrix?

[Hong Zhang]

>> Yes, modern direct solver do block factorization as super node method.
>> Can ASM type preconditioner use superlu ILUT on each subdomain?
>
> Yes.
Yes. Example
~petsc/src/ksp/ksp/examples/tutorials>mpiexec -n 2 ./ex2 -pc_type asm
-sub_pc_type ilu -sub_pc_factor_mat_solver_package superlu -ksp_view

Hong

>>
>> At preset, my solver (BCGS) only works with ASM+ILU(1) on a "smart
>> partitioned" mesh.
>>
>>
>> > The ILUTP in SuperLU (4.2 and up) exploits blocking (supernodes) in
>> >
>> > the (approximate) L & U factors.  Note the block boundary is
>> >
>> > discovered on the fly, which is usually larger than the block size
>> >
>> > from the input matrix A.  So the efficiency is pretty good.  It uses
>> >
>> > threshold dropping with partial pivoting, numerically is quite good
>> >
>> > too.    It's available only in the serial version.
>> >
>> >
>> >
>> > Sherry Li
>> >
>> >
>> >
>> >
>> >
>> > On Sun, Oct 30, 2011 at 11:18 PM, Jed Brown <jedbrown at mcs.anl.gov>
>> > wrote:
>> >
>> > > On Sun, Oct 30, 2011 at 23:50, Gong Ding <gdiso at ustc.edu> wrote:
>> >
>> > >>
>> >
>> > >> I had also considered use max block size. But it is not efficient
>> > >> here.
>> >
>> > >> Hope petsc support nonuniform block size one day.
>> >
>> > >
>> >
>> > > Inodes do a sort of partial blocking. There has to a clear performance
>> >
>> > > benefit to explicit variable blocking in order to justify the
>> > > implementation
>> >
>> > > and interface complexity. I have not yet seen a demonstration of this.
>> >
>> >
>
>
>
> --
> 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
>