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
