[petsc-users] SBAIJ: Distribution of rows

[Hong]

Florian:
>
>
> just to make sure I don't get something wrong:
>
> An SBAIJ (especially MPISBAIJ) matrix just stores the uper triangle. When
> I invoke MatSetSizes with the global dimension set (and local to
> PETSC_DECIDE) petsc tries to evenly distribute rows amoung ranks. Same when
> I set local dimensions to the same on every processor.
>
Yes.

>
> This leads to unbalanced behavior regarding the number of stored elements
> on each rank. The first row (on the first rank) is completely stored, the
> last row (on the last rank) contains just one element.
>

Not necessarily, e.g., for a sparse banded matrix, this distribution is
well-balanced. User can set their own distribution by input local rows and
set global rows as PETSC_DECIDE.

Hong
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