[Trilinos-Users] question on extracting submatrices

[Williams, Alan B]

Riccardo,
Did anyone else reply to you about this already?
Perhaps you could give a little more detail about your scenario.

Do you want B to be a 'view' such that any changes made to A automatically appear in B?
Do you want the underlying numbering to remain compatible such that mathematical operations can be performed mixing A and B (adding and/or multiplying)?

Alan


> -----Original Message-----
> From: trilinos-users-bounces at software.sandia.gov 
> [mailto:trilinos-users-bounces at software.sandia.gov] On Behalf 
> Of rrossi at cimne.upc.edu
> Sent: Thursday, December 11, 2008 1:29 PM
> To: trilinos-users at software.sandia.gov
> Subject: [Trilinos-Users] question on extracting submatrices
> 
> Dear all,
> 
> i am a new user of the Epetra, Amesos, Aztect and IFpack which we are
> currently using as an option for our  nonlinear FE analysis 
> in parallel.
> 
> First of all my felicitations to the developers. We found the 
> interface
> very good and much simpler than alternatives we looked at (PETSC)
> 
> I'd like however to ask a practical question to see if i can make
> effective use also of the meros package ;-)
> 
> suppose i have a matrix of type Epetra_FECrsMatrix 
> distributed between two
> processor
> 
> say that such matrix is
> 
> A =
> 1   2  3  4
> 5   6  7  8
> 9   10 11 12
> 13  14 15 16 17
> 
> distributed so that the first 2 lines are on proc0 and the 
> others on proc1
> 
> i would like to create a new matrix containing (say) the 
> first and third
> rows and columns of A
> 
> defined for exampel as
> 
> B =
> 1 3
> 9 11
> 
> or another containing (say the elements)
> G =
> 4
> 12
> 
> where all the elements of B can stay on the same processors 
> they were in A
> 
> does it exist any "easy" way of doing this?
> 
> thanks
> Riccardo
> 
> 
> 
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