[petsc-users] Implementing of a variable block size BILU preconditioner

[Mark Adams]

There is a reason PETSc does not have variable block matrices. It is messy
and rarely a big win. It is doable, ML/Aztec does it, but it is messy.

On Sat, Dec 1, 2018 at 6:20 PM Smith, Barry F. via petsc-users <
petsc-users at mcs.anl.gov> wrote:

>
>    Well, you need to start somewhere. It is going to take a combination of
> this, MatLUFactorSymbolic_SeqAIJ(), MatLUFactorSymbolic_SeqAIJ() and
> MatLUFactorNumerical_SeqAIJ() to get what you want. Note that one of the
> first things you need to do is given the MatGetVariableBlockSizes()
> determine the nonzero pattern of the "variable block" matrix from the
> nonzero pattern of the SeqAIJ matrix and then do a symbolic factorization
> on that new "reduced" sparse matrix. Them you do a numerical factorization
> using the "reduced sparse matrix" factorization.
>
>     Barry
>
>
> > On Dec 1, 2018, at 4:54 PM, Ali Reza Khaz'ali <arkhazali at cc.iut.ac.ir>
> wrote:
> >
> > Hi,
> >
> > I want to implement a variable block size BILU preconditioner in PETSc.
> I am wondering if modifying the PCVPBJACOBI preconditioner (vpbjacobi.c),
> to get what I want, is a good idea.
> >
> > Any help is much appreciated.
> >
> > --
> > Ali Reza Khaz’ali
> > Assistant Professor of Petroleum Engineering,
> > Department of Chemical Engineering
> > Isfahan University of Technology
> > Isfahan, Iran
> >
>
>
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