[petsc-users] Block ILU with AIJ matrix?

[Gong Ding]

Yes, modern direct solver do block factorization as super node method.
Can ASM type preconditioner use superlu ILUT on each subdomain?
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
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> the (approximate) L & U factors.  Note the block boundary is
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> discovered on the fly, which is usually larger than the block size
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> from the input matrix A.  So the efficiency is pretty good.  It uses
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> threshold dropping with partial pivoting, numerically is quite good
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> too.    It's available only in the serial version.
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> Sherry Li
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> On Sun, Oct 30, 2011 at 11:18 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
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> > On Sun, Oct 30, 2011 at 23:50, Gong Ding <gdiso at ustc.edu> wrote:
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> >>
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> >> I had also considered use max block size. But it is not efficient here.
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> >> Hope petsc support nonuniform block size one day.
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> >
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> > Inodes do a sort of partial blocking. There has to a clear performance
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> > benefit to explicit variable blocking in order to justify the implementation
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> > and interface complexity. I have not yet seen a demonstration of this.
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>