comp.lang.idl-pvwave archive: archive » Re: One ellipse to rule them all

Home » Public Forums » archive » Re: One ellipse to rule them all

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: One ellipse to rule them all [message #58706 is a reply to message #58622]

Tue, 12 February 2008 08:08

Brian Larsen
Messages: 270
Registered: June 2006

Senior Member

> My gut tells me I should be able to do it analytically. I *think* the
> two points that have the largest separation should define the major
> axis and position angle. Then I just need to fit for the minor axis
> from the rest of the points, and the largest one is the winner.

I agree with the thoughts of this posting. A little work with a pen
can go a long way.

Personally I would
- start with the ellipse you define, and maybe enlarge it some to be
sure.
- define a cost function for ameoba that adjusts the tilt angle, semi-
minor and semi-major axis where the cost is the area of the ellipse
and you can be sure it has all the points but the cost for not being
huge.
- run it and see what you get

Of course standing on the shoulders of giants is better, so if any of
the mentioned references are good (I didnt read them) then go that
route.

Cheers,

Brian

------------------------------------------------------------ -------------
Brian Larsen
Boston University
Center for Space Physics

Report message to a moderator

[Message index]

		Re: One ellipse to rule them all By: ianpaul.freeley on Mon, 11 February 2008 15:06
		Re: One ellipse to rule them all By: David Fanning on Mon, 11 February 2008 14:51
		Re: One ellipse to rule them all By: Brian Larsen on Tue, 12 February 2008 08:08
		Re: One ellipse to rule them all By: Vince Hradil on Mon, 11 February 2008 15:55
		Re: One ellipse to rule them all By: pgrigis on Mon, 11 February 2008 15:55

Previous Topic:	Re: IDL batchfile as a linux script?
Next Topic:	mpfit: what's different

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Fri Oct 10 21:13:35 PDT 2025

Total time taken to generate the page: 7.52025 seconds