[petsc-users] SLEPc - Generalized symmetric eigenproblem using ARPACK

[Harshad Sahasrabudhe]

>
> Anyway, why do you insist in using ARPACK when SLEPc's Krylov-Schur work?
> ARPACK will not give you any further advantage.


I thought ARPACK was faster when the system size is large and number of
eigenvalues required is small. I will be working with sparse matrices of
size ~60,000. Does SLEPC's Krylov-Schur have about the same performance as
ARPACK for calculating ~50 eigenvalues for such matrices?

On Wed, Mar 25, 2015 at 5:00 PM, Jose E. Roman <jroman at dsic.upv.es> wrote:

>
> El 25/03/2015, a las 21:47, Harshad Sahasrabudhe escribió:
>
> > With MUMPS you should not get spurious eigenvalues.
> > I get only a few spurious eigenvalues when using MUMPS with ARPACK, but
> the eigenvectors are definitely wrong.
> >
> > Did you try the krylovschur solver?
> > Yes, Krylov-Schur gives me correct results.
> >
> > How do you know the eigenvalues are wrong?
> > I'm testing my implementation of Schrodinger equation solver with a 3D
> harmonic oscillator potential. I'm getting correct results using FEAST and
> krylovschur solvers.
> >
> > Are you setting problem type to GHEP?
> > Yes
> >
>
> Did you try the arpack-ng version? Seems that some people have taken over
> maintainance.
>
> Anyway, why do you insist in using ARPACK when SLEPc's Krylov-Schur work?
> ARPACK will not give you any further advantage.
>
> Jose
>
>
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