Question about usage of DA object

[Matthew Knepley]

On Thu, Oct 8, 2009 at 3:21 PM, Matt Funk <mafunk at nmsu.edu> wrote:

> Hi,
>
>
> i was wondering if i can get some advice on how to use the DA objec tin
> PETSC.
>
>
> Is it possible to create a DA object by inserting a set of boxes into it?
> Or can the DA object only be used based on a single rectangular box?
>

A DA is a single rectangular prism. You could choose not to assign equations
to some vertices, or to put the identity there.

  Matt


> say my domain has 2 boxes:
> 1) (0,0) - (64,64)
> 2) (64,64) - (128,128)
>
>
> Can i "register" those 2 boxes with the object?
>
>
> If that is possible, then is it valid if certain cells/nodes of these boxes
> overlap? say they both contain cell/node (64,64)?
>
>
>
> If that is possible, and i run in parallel, will the solution on cell/node
> (64,64) be returned to both processes (the first owning box1 and the second
> box2).
>
>
>
> Right now i am building my matrix 'by hand' and i believe the mentioned
> "overlap" is causing an ill-conditioned matrix (as addressed earlier in this
> list), even through the values on the overlapping nodes are the same.
>
>
>
> thanks
> matt
>
>
>
>


-- 
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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