SLEPcEigenSolver questions

Asked by David Bernstein on 2013-04-11

Hi All, The fenics interface to the eigenvalue solver is giving me problems. For one thing, I get an error if I change the method to anything other than the default ("krylov-schur"). I also get an error if I change the problem type to "hermitian" which according to the slepc manual (http://www.grycap.upv.es/slepc/documentation/slepc.pdf) should work.

The solver is also very very slow. On a 30,000 DOF problem it takes minutes to converge (for a small number of eigenvalues) whereas on the same mesh a Poisson problem is < 0.5 seconds. Changing the tolerance parameter does not help with this.

I suspect the fenics interface is not setting up the problem correctly in PETSc. I'm using fenics 1.2 (although the same problems occurred in 1.0 and 1.1).

Thanks,
Dave

Question information

Language:
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Status:
Answered
For:
DOLFIN Edit question
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Last query:
2013-04-11
Last reply:
2013-05-09

I would be more than happy to look into this myself if someone could point me to the relevant files.

Jan Blechta (blechta) said : #2

On Thu, 11 Apr 2013 19:01:09 -0000
David Bernstein <email address hidden> wrote:
> Question #226493 on DOLFIN changed:
> https://answers.launchpad.net/dolfin/+question/226493
>
> David Bernstein gave more information on the question:
> I would be more than happy to look into this myself if someone could
> point me to the relevant files.
>

dolfin/la/SLEPcEigenSolver.cpp

Thank you, I'll look into it. Looks like it has been a year since the last set of changes whereas the latest SLEPc release (that fenics 1.2 links to) was late 2012 so maybe something has changed.

By the way, the generalized-eigenvalue demo in demo/undocumented is empty in the 1.2 release.

Anders Logg (logg) said : #5

FEniCS no longer uses Launchapd for Questions & Answers. Please
consult the documentation on the FEniCS web page for where and
how to (re)post your question: http://fenicsproject.org/support/

Anders Logg (logg) said : #6

FEniCS no longer uses Launchapd for Questions & Answers. Please
consult the documentation on the FEniCS web page for where and
how to (re)post your question: http://fenicsproject.org/support/

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