DOLFIN

SLEPcEigenSolver questions

Asked by David Bernstein

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

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David Bernstein (david-bernstein) said : 		#1

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

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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

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David Bernstein (david-bernstein) said : 		#3

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.

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David Bernstein (david-bernstein) said : 		#4

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

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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/

Revision history for this message
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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