[petsc-users] Size of off-diagonal matrix

[Matthew Knepley]

On Wed, Jun 22, 2011 at 8:55 AM, John Fettig <john.fettig at gmail.com> wrote:

> I'm having trouble understanding how the size of off-diagonal matrix
> is determined in the MPIAIJ format.  For example, if I run on 2
> processors the global size is 4177x4177, but the local matrices are
>
> Rank 1:
> 2089x2089  (diagonal block)
> 2089x259  (off diagonal block)
>
> Rank2:
> 2088x274  (off diagonal block)
> 2088x2088 (diagonal block)
>
> Why isn't the off-diagonal block sized for all of the off-diagonal columns?


It is compressed, so it only has columns that have a nonzero.

   Matt


>
> John
>



-- 
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener
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