[petsc-users] eigensolution error with slepc

[Matthew Knepley]

On Mon, Apr 4, 2016 at 9:42 AM, Manav Bhatia <bhatiamanav at gmail.com> wrote:

> Ok. So, I ran ex7 with the same command-line options in your email, and
> got a result. This is on my Mac OS X, without any changes to the
> lapack/blas/slepc library.
>
> I also ran my code on a linux machine with lapack/blas build from source
> (obtained from netlib), and got the same error as on my mac.
>
> Not sure how to go about debugging this.
>

Sounds like a memory error. Run with valgrind.

   Matt


>
> -Manav
>
>
> > On Apr 4, 2016, at 3:46 AM, Jose E. Roman <jroman at dsic.upv.es> wrote:
> >
> >
> >> El 3 abr 2016, a las 22:17, Manav Bhatia <bhatiamanav at gmail.com>
> escribió:
> >>
> >> I just send you the matrices.
> >>
> >> Thanks,
> >> Manav
> >
> > I cannot reproduce the problem. I was able to compute the eigenvalues
> without problems with Krylov-Schur (note that I scaled matrix A by 1e7
> because the eigenvalues are tiny):
> >
> > $ ./ex7 -f1 A.petsc -f2 B.petsc -eps_gen_hermitian
> >
> > Generalized eigenproblem stored in file.
> >
> > Reading REAL matrices from binary files...
> > Number of iterations of the method: 1
> > Number of linear iterations of the method: 17
> > Solution method: krylovschur
> >
> > Number of requested eigenvalues: 1
> > Stopping condition: tol=1e-08, maxit=768
> > Linear eigensolve converged (6 eigenpairs) due to CONVERGED_TOL;
> iterations 1
> > ---------------------- --------------------
> >            k             ||Ax-kBx||/||kx||
> > ---------------------- --------------------
> >       11.410228            3.18851e-09
> >        1.323631            2.33005e-09
> >        1.323631            3.98884e-09
> >        0.224497            1.24334e-08
> >        0.168344            9.81685e-08
> >        0.129229            4.85372e-08
> > ---------------------- --------------------
> >
> > Note that I am solving the problem as a GHEP, and this gives far better
> residuals than solving as a GNHEP. The Arnoldi solver did not fail either.
> >
> > I don't know what caused your error. You can try configuring with the
> source Lapack: --download-f2cblaslapack
> >
> > Jose
> >
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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