[petsc-users] SLEPc generalized eigenvalue problem question?

[Matthew Knepley]

On Mon, Aug 1, 2011 at 5:27 PM, John Chludzinski <jchludzinski at gmail.com>wrote:

> I create 2 matrices using:
>
> MatCreateSeqDense(PETSC_COMM_SELF, n, n, Ka, &A);
> MatCreateSeqDense(PETSC_COMM_SELF, n, n, Kb, &B);
>
> These matrices are 99% zeros ( 16,016,004 entries and 18660 non-zeros).
>  They are symmetric and real.  Their tri-diagonal elements are non-zero plus
> a few other entries.
>

Please give some justification for doing this? On the surface, it just seems
perverse.

   Matt


> I tried to use ex7 for the generalized eigenvalue problem:
>
> ./ex7.exe -f1 k.dat -f2 m.dat -eps_gen_hermitian -eps_smallest_real > x.out
> 2>&1
>
> without specifying an EPS and get:
>
> Generalized eigenproblem stored in file.
>
> Reading REAL matrices from binary files...
> Number of iterations of the method: 500
>  Number of linear iterations of the method: 4009
> Solution method: krylovschur
>
> Number of requested eigenvalues: 1
> Stopping condition: tol=1e-07, maxit=500
> Number of converged approximate eigenpairs: 0
>
> Is krylovschur inappropriate for this problem or have I set up the problem
> incorrectly by using   MatCreateSeqDense(...) to create the matrix input
> files in PETSc binary form?
>
> ---John
>



-- 
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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