[petsc-users] SLEPc Bogus eigenvalues for large -eps_nev

[Jose E. Roman]

El 14/05/2015, a las 19:13, Vijay Gopal Chilkuri escribió:

> oups sorry, I send you a smaller one (540540) this should finish in a few minutes.
> 
> It requires the same makefile and irpf90.a library.
> so just replace the old problem.c file with this and it should compile.
> 
> Thanks again,
>  Vijay
> 

I was able to compute 300 eigenvalues of this matrix of size 540540. All eigenvalues are in the range -4.70811 .. -4.613807, and the associated residual is always below 1e-9.

There must be something in your software configuration that is causing problems. I would suggest trying with a basic PETSc/SLEPc configuration, with no openmp flags, using --download-fblaslapack (instead of MKL). Also, although it should not make any difference, you may want to try with a smaller number of MPI processes (rather than 741).

Jose