Hi pymor,

for Dirichlet-dofs, an operator gets a "1" on the diagonal and the rhs gets the Dirichlet value set. This is done in operators/cg.py. However, this may worsen the condition of the operator: E.g. if all other eigenvalues are of order 1e5, adding an eigenvalue of 1e0 leads to bad behavior of sparse solvers.

It would be better to put a value on the diagonal which is of comparable size to the other entries in the matrix.