[petsc-users] eigensolution error with slepc

[Manav Bhatia]

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. 

-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
>