[Nek5000-users] Building mass and stiffness matrices

[nek5000-users at lists.mcs.anl.gov]

Dear users and developers,
I am using NEK5000 for a 3d unsteady simulation with mixed Dirichlet and periodic bc. For the post-processing (a POD-based dynamics) I need the global mass and stiffness matrices as built by NEK5000 on my mesh. I would also need the matrix having as entries (phi_i, grad(phi_j)) where phi are the basis polynomials.
Is it possible to have NEK build these matrices and then save them on file? The ultimate goal is to import them on a PETSc program to perform some algebraic manipulations. I already found a way to import the simulations' results.
Surfing the code, I have found some 1-d routines, but I don't know how to extend them to my needs.
Thank you in advance for any help or hint.
Best regards,
Giuseppe