This is a rather incomplete implementaion of work done by Gudrun Putze-Meier. I
have to confess that I never read her original paper. So all credit belongs to
her, all bugs are mine. I tried to get some insight from an implementation of
two students of mine. They remain anonymous because their work was the wost
piece of code I ever saw. My code behaves mostly as their implementation did
except it is about 75 times faster.