Irene,
I believe that you are looking at that really slow and confusing definition that I did many months ago for the hypar. I have a way better version that I've been working on lately. The entire thing is coded as a VB component now and runs very fast so that you can generate hypars with very many folds (many thousands). See my comment on this thread for the code:
http://www.grasshopper3d.com/xn/detail/2985220:Comment:62410
(it is file called hypar.ghx)

Oh, and in reply to your question, that formula was the length of the edge, which was calculated by how many folds out you are from the center.

Your blog is very nice, by the way.

Hey,

I think the main idea is that you must know all of the lengths of the fold lines on the flattened object, before folding it (or be able to calculate them as I was). Try posting your files and images to the discussion board - there are many people here who are better at this than I am, and I'm on vacation right now, so it is hard to really think about this stuff. (I just graduated 3 days ago!)

-Chris