[Trilinos-Users] AztecOO AZ_reuse question

[Heroux, Michael A]

Siva,

It's been a while since I have looked at this, but there is a method called
ConstructPreconditioner (I think), that will do what you want, rather than
doing a single iteration.  Also, as long as the inner AztecOO object remains
alive, you do not have to set the AZ_reuse flag.

I think the issue you have is that you are mixing the old and new
programming styles.

Finally, I think there might be an example in the AztecOO directories that
show an inner outer usage.

Mike



On 3/2/11 1:54 AM, "Siva Rajamanickam" <srajama at sandia.gov> wrote:

> I am trying to use AztecOO for both inner and outer iterations in a new
> preconditioner. I create my new Ifpack style preconditioner. Set that as a
> preconditioner for my AztecOO  solver (solver1) for outer iteration.
> 
> Inside my new preconditioner's compute
>   I create another AztecOO solver (solver2) (for inner iteration), set a
> smaller problem (for the Schur complement) and the other options. Set
> AZ_keep_info to 1, do a dummy iterate() so the preconditioner gets
> constructed. Then I set AZ_pre_calc to AZ_reuse and exit out of my compute.
> 
> Inside my new preconditioner's ApplyInverse
>   I use the solver to solve for the Schur complement system. The expectation
> is that solve will use the already constructed preconditioner. However, I get
> 
> Error: Did not find previous factorization (requested
> by setting options[AZ_pre_calc] to AZ_reuse).
> To find this factorization, the following
> parameters must match the previous factorization:
> 1) Total number of unknowns.
> 2) options[AZ_overlap]
> 3) options[AZ_scaling]
> 4) options[AZ_precond]
> 5) options[AZ_reorder]
> 6) options[AZ_type_overlap]
> 7) options[AZ_subdomain_solve]
> 8) options[AZ_graph_fill]
> 9) params[AZ_ilut_fill]
> 10) params[AZ_drop]
> 11) data_org[AZ_name]
> XXXP14 '*! 1.0266XXX -7923 208
> (   -7923,     208  373793856) ==> P14 '*! 1.0266
> ( -914901,   15872  373827424) ==> vblock in gmres0
> ( -914901,     512  373746480) ==> ptrs in gmres0
> ( -914901,   10200  373817136) ==> general in gmres0
> (    2073,      80  373754000) ==> T48 +1! 1.0295
> (    2073,     208  373740272) ==> P48 +1! 1.0295
> (    2077,     112  373740064) ==> x_reord P14 '*! 1.0266
> (    2077,     612  373770976) ==> bindx P14 '*! 1.0266
> (    2077,    1224  373738576) ==> val P14 '*! 1.0266
> (    2077,      60  373748016) ==> iu P14 '*! 1.0266
> (    2077,      60  373747856) ==> ordering P14 '*! 1.0266
> (    2077,      60  373692640) ==> inv_ordering P14 '*! 1.0266
> (    2077,     224  373692320) ==> A_over P14 '*! 1.0266
> (    2077,      80  373768608) ==> T14 '*! 1.0266
> (    2077,     208  373768320) ==> P14 '*! 1.0266
> 
> I tried setting the first 10 of the options in my compute explicitly, but that
> doesn't help. I don't how to set the data_org.
> 
> The following two cases work:
> 1. If I create a new solver every time inside my ApplyInverse method then it
> works fine. But that is terribly inefficient.
> 
> 2. I tried two consecutive dummy iterate() calls within my compute then it
> works fine as well.
> 
> Here is some pseudo code
> Inside the class definition I do
>     Teuchos::RCP<Epetra_CrsMatrix> Sbar_;
>     AztecOO *solver_;
>     Epetra_MultiVector *Xs;
>     Epetra_MultiVector *Bs;
> 
> In the compute I do
>  solver_  = new AztecOO() ;
>  int err = solver_->SetUserMatrix(Sbar_.get());
>  solver_->SetAztecOption(AZ_solver, AZ_gmres);
>  solver_->SetAztecOption(AZ_precond, AZ_dom_decomp);
>    // Do a dummy iterate to construct the preconditioner
>     Epetra_Map BsMap(-1, Snr_, SRowElems_, 0, A_->Comm());
>     Xs = new Epetra_MultiVector(BsMap, 1);
>     Bs = new Epetra_MultiVector(BsMap, 1);
>     Bs->PutScalar(1.0);
>     solver_->SetLHS(Xs);
>     solver_->SetRHS(Bs);
>     solver_->Iterate(30, 1e-10);
> 
>     solver_->SetAztecOption(AZ_pre_calc, AZ_reuse);
> 
>     cout <<"Calling one more time in setup itself " << endl;
>     Bs->PutScalar(2.0);
>     solver_->Iterate(30, 1e-10); // This works
> 
> In the ApplyInverse
>    Xs->PutScalar(0.0);
>   Bs to random value
>   solver_->Iterate(30, 1e-10); // This fails
> 
> Any help will be appreciated.
> 
> Thanks
> Siva
> 
> 
> 
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