5 Point Ellipse?

[fahim108]

Is there any Command / Lisp / Parametric way of obtaining a "prospective" ellipse from a set of 5 points?

 

 

I found a similar question here, but no solution.

[JD Mather]

What are the (x,y) coordinates of the 5 points?

[fahim108]

P1 (0.6504, 0.1714), P2 (0.6722, 0.1834), P3 (0.7011, 0.2022), P4 (0.7408, 0.2338 ), P5 (0.7977, 0.2927)

 

I'm fiddling with the Geometric Constraints option but haven't gone far enough!

[JD Mather]

The dimensions in (parenthesis) are for reference only.

I was able to easily find the geometric solution in Autodesk Inventor. (I thought I would have to have beyond 4 decimal places, but only if the major and minor axis had to be a known value.)

I will have to experiment in AutoCAD to see if I can get AutoCAD to solve the problem.

 

 

Oops, I realized I made a mistake in the y-coordinate of P5.

This is the beauty of parametric geometry constraints - I only had to edit the dimension to correct the solution.

 

[Lee Mac]

Here is my solution: 5-Point Ellipse

[fahim108]

Here is my solution: 5-Point Ellipse

 

I've loaded the LISP but am unable to call it? I tried entering test but it doesn't work! Am I doing something wrong?

 

I will have to experiment in AutoCAD to see if I can get AutoCAD to solve the problem.

 

Any luck?

Edited July 12, 2013 by fahim108
Added quotes!

[Lee Mac]

I've loaded the LISP but am unable to call it? I tried entering test but it doesn't work! Am I doing something wrong?

 

Have you downloaded & loaded the 5PointEllipse.lsp program (from the download link found at the top of the page), before saving & loading the short example program at the bottom of the page?