Hi,

I am using the eigenvalue solver from the documentation with the Crouzeix-Raviart FESpace already implemented by you ( docu.ngsolve.org/test/i-tutorials/unit-2…envalues/pinvit.html).

By using it I observed that something is not working right, since around the meshisize of h=0.1 the L2-error of the eigenvectors begin to grow again (instead of converging) and also the eigenvalue “explodes” (with h= 0.01 I get an eigenvalue of 132.68, while the exact one is 19.74). I tried to use the eigenvalue solver with the H1 space and with that, the eigenvalue converges to the exact one and the L2-error of the eigenvectors converges. So I’m guessing that something is not working right when using the nonconforming space with the eigenvalue solver.

Has anyone noticed something similar to that or has an idea why this happens?

Bests,

Melanie