Good idea, but you can make that qd_type-independent, using the _K_DEPENDENT attribute from the QDeltaGenerator class :

if self.generator._K_DEPENDENT:
    self.QI = self.get_Qdelta_implicit(qd_type=self.generator.__class__.__name__, k=k)

... I think (to be tested). It's not the cleanest way of doing it, but at least we won't have to change it for other variable preconditionners.

Oh, wait ... the generator attribute is used for both implicit and explicit terms ! This has to be corrected

Suggestion : instead of having only one generator attribute, put instead a genQI and genQE attribute, that are used separately for the implicit and explicit QDelta matrices. And the setupGenerator must be quickly adapted to allow that

Are we happy here?

Yes 😄