I've used spirals for some stock market related stuff, and I found the following to be helpful regarding evolutes (starting in the center and working outward):
http://code.jsoftware.com/wiki/Doc/Articles/Play132 Henry Rich, J programming forum, 24 Dec 2012 and 27 Dec 2012 Hope this helps a bit! Harvey ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
