[petsc-users] Block-ILU in Petsc

[Jed Brown]

On Fri, Oct 14, 2011 at 09:09, behzad baghapour
<behzad.baghapour at gmail.com>wrote:

> 1- If I set BAIJ for Mat, then the ILU preconditoner automatically
> recognize to use Block-version of ILU preconditioners? (like VBILUM
> developed by Saad and coworkers) or I should do more for Block
> preconditioning?
>

Yes, block ILU, block SOR, etc.


>
> 2- "the block size is the same the matrix block size" means that there is
> no way to combine the matrix elements to build blocks of possible maximum
> size like Hash method or something like this?
>

For AIJ, there are "Inodes" which automatically detect identical rows where
blocking can be used. This helps more or less, depending on the hardware.
There is no such thing for BAIJ, but it wouldn't offer much improvement in
memory performance anyway. BAIJ performance approaches dense mat-vec as long
as the ordering is such that the vector can be reused.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20111014/d360a87b/attachment.htm>