[Trilinos-Users] [EXTERNAL] Why does Anasazi bail out early?

[Baker, Christopher G.]

How about "Num Restarts"?

-----Original Message-----
From: Nico Schlömer [nico.schloemer at gmail.com<mailto:nico.schloemer at gmail.com>]
Sent: Monday, August 20, 2012 07:43 PM Eastern Standard Time
To: Thornquist, Heidi K
Cc: trilinos-users at software.sandia.gov
Subject: Re: [Trilinos-Users] [EXTERNAL] Why does Anasazi bail out early?


Yep, I'll definitely look at operator transformations, but first I
wanted to make that the code works as it is. My main problem right now
is the fact that I can deduct little to nothing about what went wrong
from the bare logs.
The parameters I used are

MyProblem->setHermitian(true);
MyProblem->setNEV(10);

MyPL.set("Which", "LM");
MyPL.set("Block Size", 2);
MyPL.set("Num Blocks", 10);
MyPL.set("Convergence Tolerance", 1.0e-5);

The log file is attached.

--Nico



On Tue, Aug 21, 2012 at 1:14 AM, Thornquist, Heidi K <hkthorn at sandia.gov> wrote:
> Hi Nico,
>
> What are the parameters that you are passing block Krylov-Schur?
>
> This type of solver will have a hard time computing the smallest magnitude eigenvalues without a spectral transformation, like shift-invert or Cayley.  It looks like you are using one since the Ritz values are being printed out with the largest magnitude first, so what are you using and what is the shift?  It looks like you set the eigenproblem as Hermitian (since the output is not printing out any imaginary part of the eigenvalue).  You might consider using block Davidson or LOBPCG for your problem instead since they can more easily find the smallest eigenvalues.
>
> If you want to send me a log of the output you receive using all those verbosity flags, that would also help.
>
> Thanks,
> Heidi
>
>
> ________________________________________
> From: trilinos-users-bounces at software.sandia.gov [trilinos-users-bounces at software.sandia.gov] on behalf of Nico Schlömer [nico.schloemer at gmail.com]
> Sent: Monday, August 20, 2012 5:02 PM
> To: trilinos-users at software.sandia.gov
> Subject: [EXTERNAL] [Trilinos-Users] Why does Anasazi bail out early?
>
> Hi,
>
> I'm trying to use Anasazi for computing a bunch of SM eigenvalues, and
> while things compile and run fine, the iterations always aborts
> prematurely without indicating what went wrong. If the tolerance is,
> say, 1.0e-15, a typical last block of output (with verbosity
> Anasazi::IterationDetails + Anasazi::Errors + Anasazi::Warnings +
> Anasazi::StatusTestDetails + Anasazi::Debug + Anasazi::FinalSummary)
> would be
>
> =========================== *snip* ===========================
>
>                          BlockKrylovSchur Solver Status
>
> The solver is initialized.
> The number of iterations performed is 110
> The block size is         2
> The number of blocks is   10
> The current basis size is 20
> The number of auxiliary vectors is 0
> The number of operations Op*x   is 220
>
> CURRENT RITZ VALUES
>           Ritz Value       Ritz Residual
> --------------------------------------------------------------------------------
>         8.075243e+00        5.120182e-04
>         8.063177e+00        4.056698e-04
>         8.063150e+00        3.596635e-03
>         8.050790e+00        1.081923e-02
>         8.042772e+00        9.878716e-03
>         8.027045e+00        4.533151e-02
>         8.015636e+00        4.997743e-02
>         8.014430e+00        1.482199e-02
>         7.983605e+00        6.111459e-02
>         7.963543e+00        5.082745e-02
>
> Returning 0 eigenpairs to eigenproblem.
> =========================== *snap* ===========================
>
> Note how the tolerance isn't met.
> How can I find out what's going on?
>
> Cheers,
> Nico
>
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