Block-smoothers with variable block size

[Nicolas Tardieu]

Dear Barry,

I have a few questions about inodes :
- can the user specify the inodes sizes (it seems to me this is an automatic
PETSc feature to gain performance, right?)?
- can the inodes have different sizes?

Otherwise I plan to define a new matrix type MATSEQVBAIJ (VB for variable
block) based on MATSEQAIJ with an additional attribute defining the block
sizes.

Thanks,

Nicolas

2008/3/20, Barry Smith <bsmith at mcs.anl.gov>:
>
>
>    DON"T USE GREP! Use etags
> # To access the tags in EMACS, type M-x visit-tags-table and specify
> # the file petsc/TAGS.
> # 1) To move to where a PETSc function is defined, enter M-. and the
> #     function name.
> # 2) To search for a string and move to the first occurrence,
> #     use M-x tags-search and the string.
> #     To locate later occurrences, use M-,
>
>    It may not be in petsc-2.3.3 you may need to use petsc-dev
> http://www-unix.mcs.anl.gov/petsc/petsc-as/developers/index.html
>
> it is in src/mat/impls/aij/seq/inode.c
>
>
>
>     Barry
>
>
>
> On Mar 20, 2008, at 1:52 PM, Nicolas Tardieu wrote:
>
> > Dear Barry,
> >
> > Thank you very much for your quick answer.
> > I am searching for MatRelax_Inode in PETSc src directory using grep.
> > But I just can't find it! Please note I am using 2.3.3p6
> > Could you please tell me where this routine is?
> >
> > Nicoals
> >
> > 2008/3/20, Barry Smith <bsmith at mcs.anl.gov>:
> >     Nicolas,
> >
> >      Actually we are very close to this. Check out the routine
> > MatRelax_Inode() which is for AIJ matrices.
> > For the block size it uses the inode size. If your matrix has inodes
> > that match the blocks you want
> > then everything is there already just use the PCSOR.
> >
> >      If you do not have inodes then you can mimic the MatRelax_Inode()
> > code to make a new
> > routine MatPBRelax_SeqAIJ(). If you do implement this we'd love to add
> > it to PETSc.
> >
> >
> >      Please let us know if you have additional questions.
> >
> >
> >     Barry
> >
> >
> >
> >
> > On Mar 20, 2008, at 1:07 PM, Nicolas Tardieu wrote:
> >
> > > 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,
> > >
> > > Nicolas
> > >
> >
> >
>
>
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