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

[Baker, Christopher G.]

What is the convergence criterion? Did the solver indicate by return value that it had not converged?

-----Original Message-----
From: Thornquist, Heidi K [hkthorn at sandia.gov<mailto:hkthorn at sandia.gov>]
Sent: Monday, August 20, 2012 07:15 PM Eastern Standard Time
To: Nico Schlömer; trilinos-users at software.sandia.gov
Subject: Re: [Trilinos-Users] [EXTERNAL] Why does Anasazi bail out early?


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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