The required formulae are recursive and unfortunately I can't remember any of
them off the top of my head. I have some reference material at home and will
see what I can dig out for you over the next few days.
If you can track down a copy of Chaos, it would help you in tweaking your own
programs.
jw
Thanks, jody, for whatever help you can provide. i have a copy of the book
handy, but nothing that can be directly translated into a formula in there that
i can find.
Just get your hands on a copy of FRACTINT, the wonderful freeware fractal
program. It explains all the formulas real well — and you can get the source,
too.