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There are several "versions" of ovals. Descartes' ovals take the form f*d1+g*d2=s d1, d2 are the distances of a point on the curve to the two foci (as with an ellipse) f, g are rational numbers. I've taken f<1 and g=1. s is a number fixed for a given curve.
The equation 2*d1+d2=s can be drawn as follows. As for an ellipse, put 2 tacks into a sheet of paper. Take a piece of string length, s. Tie one end to one tack. Insead of tying the other end to the other tack as for the ellipse tie it to a pencil and then loop the string round the remaining tack. The pencil is tensioned against the string (as for an ellipse). The string length is thus made up of 2 lengths of d1 and one of d2. Mike
----- Original Message ----- From: "Russell, Ken" <krussell@xxxxxxxxxxxxxxx>
Sent: Thursday, March 08, 2007 6:29 PM
Subject: oval question
How would one write a procedure to create an oval in logo? I think it will use a little trig in there (sin?), but I'm (really) unclear on the concept.
To save an attachment to your computer, PC users should right-click (Mac users, click and hold the mouse button) on the link and then choose 'save target as' from the pop-up menu. A window will then pop up in which you can choose a location for the file.