DIYbanter - View Single Post

Oleg Lego (in ) said:

| The Guess who entity posted thusly:
|
|| On Mon, 20 Feb 2006 12:50:59 -0600, Oleg Lego
|| wrote:
||
||| That was my plan... I only need a few templates to form a
||| framework to be filled. I was going to use the "hanging chain
||| catenary" for it, but this will be easier.
||
|| They are different. You can still as easily plot the catenary
|| though if that's what you want. Nobody will notice the difference
|| [or be too interested.] You'll need the parabola if you need a
|| focal point.
|
| Interesting. I was told that a catenary was a parabola. Of course it
| was a web page somewhere that told me this, and we all know how
| absolutely accurate web pages are. I will need a focal point, so
| thanks for the info.

They're actually very different critters, as you can see from the
"shape" of their defining equations (source: Burington's "Handbook of
Mathematical Tables and Formulas") -

Catenary: y = a * (exp(x / a) + exp(-x / a)) / 2

Parabola: 4 * a * (y - k) = (x - h) * (x - h)

For a wine rack, I think I'd want concave circular arcs to support the
bottles - with either a horizontal flat or an ornamental convex curve
connecting those arcs. A repeating ogee might give an interesting
appearance...

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