Question about usage of DA object

Matt Funk mafunk at
Thu Oct 8 15:21:44 CDT 2009


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?

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 

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.


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