[help-3dldf] Re: your mail

[Laurence Finston]

Hi Martijn,

On Sat, 5 Nov 2005, Martijn van Manen wrote:

>
> Hope this helps a little. It is not exact. But it should tell you about how
> to approach
> your problem.
> An ellipse in the plane is determined by five points.
>

Thanks for your reply.  Nice to hear from you again.  I've just logged
on, so I haven't had a chance to look at the PDF file yet.

I've made a bit of progress on the problem.  I can get as many points as I
want, but I need to get them sorted.  I didn't manage it yesterday, but I
think I know how to do it now.

Obviously, it's a naive way of doing it.  I found a reference in Heinrich
Brauner's _Lehrbuch der Konstruktiven Geometrie_ ("Lehrbuch" is
"Teaching-Book", for non-German speakers).  He gives a general solution
for the intersection of a quadric with a plane.  However, it's on about
page 400 and I don't understand it, not having read the first 399
pages.

Thanks again, and I'll write again if I have any questions.

Laurence