You have probably already noted that there are several forms for expressing
the equation of a parabola, some perhaps more convenient than others for
deriving the associated arc length expression in a compact form for
programming your Shopbot.

You might find these sites helpful for optical effects visualization:
http://www.geocities.com/thesciencef...ola/focus.html
http://www.cut-the-knot.org/ctk/Parabola.shtml
Amateur telescope makers (ATM) are often very interested in parabolic
mirrors as in Newtonian telescopes.

And you probably already know about this site that I stumbled across (DAGS
"solar concentrators"): http://www.redrok.com/main.htm

David Merrill



"Morris Dovey" wrote in message
...

Dave...

Thanks - I'd done a google search and hadn't found an article that I
could regognize as a solution to my problem (may be a vocabulary
problem on my part) and guessed (correctly) that this would be a good
forum in which to ask.

It's interesting to note that a query to rec.woodworking produced a
usable solution immediately, while the same query to sci.math (where
it's probably more topical) hasn't produced any response at all.

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/solar.html