[Trilinos-Users] Starting out suggestions

Heroux, Michael A maherou at sandia.gov
Thu Dec 30 12:38:45 MST 2010


You have figured out quite a bit already.  Very good.

There are several choices you can make going forward.  Here are some options:

 *   Yes, converting from the ublas to Epetra is the first required step.  As an alternative, you might consider trying Tpetra.  Although newer, more complicated and having a few know performance disadvantages vs. Epetra, Tpetra provides compilation targets for multicore and GPUs, supports multiple floating point and integer types and is where most of the manycore research in Trilinos is occurring.  However, using Epetra first is not bad, even if you might be interested in

Tpetra eventually, since they have very similar APIs.

Ifpack is a good choice for preconditioning options, but has a similar counterpart as Epetra, called Ifpack2.  Ifpack2 is based on Tpetra and is again where all of the manycore and multiprecision work is going.  Once again, switching to Ifpack2 later should be fairly straight-forward.
 *   We have two iterative solver packages: AztecOO and Belos.  Similar to the above discussion, AztecOO is based on Epetra solely.  Belos supports both Epetra and Tpetra, and can support multiprecision.
 *   Stratimikos is a good option to manage the use of preconditioners and iterative solvers.  It allows easy switching between AztecOO and Belos, and preconditioner packages Ifpack and ML.  It will eventually support Tpetra and Ifpack2, but doesn’t right now.

So, the general advice:

For best MPI-only performance today with a robust double-precision-only and mature software stack, you can use Epetra with AztecOO (or Belos), Ifpack and ML (which is necessary for scalability eventually).  You can use the solvers and preconditioners via Stratimikos, which is very convenient.

For future oriented software development, the Tpetra/Belos/Ifpack2 option is viable.

I hope this helps.


On 12/30/10 12:10 PM, "Luke Bloy" <lbloy at seas.upenn.edu> wrote:

> Hi,
> I'm new to trilinos and am looking for some suggestions on where to start.
> My immediate application is to repeatedly ( 10,000 - 500,000 times)
> solve a sparse linear system defined by a non-symmetric matrix A. The
> size of A is roughly 2,000,000 square but with only ~ 30,000,000
> unknowns. The RHS of these systems will also generally be fairly sparse.
> In my head the procedure would be.
> 1) Convert ublas csr matrix to Eperta format.
> 2) compute an ILU or other preconditioner (ifpack)
> 3) then solve each RHS
> I've just begun to go through the tutorials and documentation. At first
> if seemed I should be looking at Belos and ifpack or perhaps Amesos. but
> then I came across Stratimikos and thought that looked promissing.
> So i guess my question is where should i start?
> Thanks in advance.
> Luke
> _______________________________________________
> Trilinos-Users mailing list
> Trilinos-Users at software.sandia.gov
> http://software.sandia.gov/mailman/listinfo/trilinos-users
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