[petsc-users] eigensolution error with slepc

[Jose E. Roman]

> 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