[petsc-users] ASM Index Sets [Repost with Correction]

[Justin Droba (JSC-EG3) [JETS]]

Dear all,

Very sorry to flood the mailing list, one final post because the image 
will not come through if you're on digest or using plain text.

Thank you for maintaining this wonderful software and this user mailing 
list!

I am attempting to use an additive Schwartz preconditioner with multiple 
blocks per processor.  I've been able to get it to work with one block 
per processor but not been successful with multiple. I believe I am not 
understanding correctly the construction of index sets for this case.

Let's consider a simple example: 16 nodes on a square with 4 blocks of 4x4:

Image

https://farm2.staticflickr.com/1633/25912726941_428d61ae87_o.png


I want to put Omega_1 and Omega_2 on processor 1 and the other two on 
the second processor.  Do I make my index sets on processor 1

IS = {  {1,2,3,5,6,7,9,10,11}, {2,3,4,6,7,8,10,11,12} }
IS_LOCAL = { {1,2,5,6}, {3,4,7,8} }

and similarly for the other processor?  I tried this and it isn't quite 
working out.  Do I misunderstand something?

Thank you!

Best regards,
Justin

-- 
---------------------------------------------
Justin Droba, PhD
Applied Aeroscience and CFD Branch (EG3)
NASA Lyndon B. Johnson Space Center
JETS/Jacobs Technology, Inc. and HX5, LLC

*Office:* Building 16, Room 142
*Phone*: 281-483-1451
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