# How is the proof that the Quartimax/Varimax-rotation converges?

Empirically the quartimax-/varimax-rotation has proven useful and it was always converging in my applications. But from my readings years ago I have a vague remembering, that the fact of a proof of convergence has been mentioned but I've never seen the actual proof.

Perhaps this is not difficult and may be done here, or does someone have a reference?

What I'm really after is the proof for the "inverse" of the quartimax: where the rotation is defined for the minimizing (instead of the maximizing) of the criterion; I hope I can use the quartimax-convergence-proof directly or at least have a path how to proceed with such a proof on my own...

[update] Hmm, I've got some hint to articles of ten Berge(1995, 60(3)) and of Jennrich(2001, 66(2)) (both appeared in "Psychometrika" that couple of years ago), which both seem to deal with problems of the convergence of that rotation - so this seems not to be trivial (or as easy as I hoped it would possibly be)...