[petsc-dev] MetSetBlockSize issue

[Dmitry Karpeev]

On Wed, Apr 25, 2012 at 4:58 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> On Wed, Apr 25, 2012 at 16:41, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>>  I admit MatSetVirtualColumnBlockSize() is clunky and would be happy to
>> hear alternatives.
>
>
> What about having a separate row and column block size? The BAIJ and MAIJ
> formats can continue to store data using bs=gcd(rowbs,colbs), but those row
> and column block sizes indicate that redundancy exists in the data
> structure, so it can be utilized by appropriate operations.
>
I agree.
In fact, P's "column block size" (cbs) has exactly that meaning in the GAMG
code (e.g., formProl0() in gamg/agg.c) -- it sets matrix values in adjacent
multiples of cbs within each row. MatPtAP() could easily impart that block
size (cbs = rbs, in this case) to its result.  This way the meaning of
"column block size" and "row block size" are meaningful for any matrix and
not just within some particular context.

Dmitry.
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