Block-smoothers with variable block size

Nicolas Tardieu niko.karin at
Thu Mar 20 13:07:00 CDT 2008

Dear PETSc experts,

I am currently designing a multigrid PC that needs to operate on variable
block size matrices. I know PETSc does not support this feature.
So, I will do it "by hand".  Neverthless I would like to be able to use some
smoothers like Jacobi or SOR in their block version.

What is the best solution that would work both in sequential and parallel?

- define some MATSHELL that handle variable block size
    -> will I be able to use in some way a block Jacobi or SOR?
    -> would it be possible to use CSR inside the MATSHELL and manage the
variable blocks.

- use a AIJ matrix and manage the blocks using some indirection mechanism
and reprogram Jacobi or SOR

Thank you,

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