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Re: Incorrect fit of elliptic to data [message #35995] Mon, 04 August 2003 14:06
active-news is currently offline  active-news
Messages: 1
Registered: August 2003
Junior Member
I was thinking that supplying the data and the code in this way would be the
best but I now believe that I made a mistake in doing that, I apologize for
that.

Thank you for recommending your MPFITELLIPSE program, I think that will be
better suited for what I want to do and I will have a look at it.

Johan


"Craig Markwardt" <craigmnet@cow.physics.wisc.edu> wrote in message
news:onznipgr1h.fsf@cow.physics.wisc.edu...
>
> "active-news" <johan_marais@absamail.co.za> writes:
>
>
>> I am using the program from David Fanning's site (FIT_ELLIPS) to fit an
>> ellips to edge points detected from profiles but the fitted ellips seems
to
>> be bigger than the supplied data. Anyone that can help?
>
> (a) you just dumped a big uuencoded file into the newgroup. Why?
>
> (b) you uuencoded the text edges.pro file too. Why?
>
> (c) It was difficult to get your script to work. There was no
> documentation. Depending on where I clicked, I got different results,
> I suppose I am supposed to click the center? The logic of the program
> is complex enough that it is difficult to decide what *should* be
> happening.
>
> (c) you assumed that Fanning's fit_ellipse function is for fitting
> elliptical shells, when clearly the examples show solid elliptical
> disks. That script computes the size of the ellipse based on the
> moment of inertial of the "blob." Is that what you want?
>
> (d) Have you considered other programs, which actually fit an
> elliptical contour to XY scatter data? (such as MPFITELLIPSE)
>
> Craig
Re: Incorrect fit of elliptic to data [message #35999 is a reply to message #35995] Mon, 04 August 2003 12:38 Go to previous message
David Fanning is currently offline  David Fanning
Messages: 11724
Registered: August 2001
Senior Member
Craig Markwardt writes:

> (a) you just dumped a big uuencoded file into the newgroup. Why?
>
> (b) you uuencoded the text edges.pro file too. Why?
>
> (c) It was difficult to get your script to work. There was no
> documentation. Depending on where I clicked, I got different results,
> I suppose I am supposed to click the center? The logic of the program
> is complex enough that it is difficult to decide what *should* be
> happening.
>
> (c) you assumed that Fanning's fit_ellipse function is for fitting
> elliptical shells, when clearly the examples show solid elliptical
> disks. That script computes the size of the ellipse based on the
> moment of inertial of the "blob." Is that what you want?
>
> (d) Have you considered other programs, which actually fit an
> elliptical contour to XY scatter data? (such as MPFITELLIPSE)

All I know is that if I had to do this technical support
gig for a living, I would charge a hell of a lot more for
it than I do now. :-(

Cheers,

David

--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
Re: Incorrect fit of elliptic to data [message #36000 is a reply to message #35999] Mon, 04 August 2003 12:29 Go to previous message
Craig Markwardt is currently offline  Craig Markwardt
Messages: 1869
Registered: November 1996
Senior Member
"active-news" <johan_marais@absamail.co.za> writes:


> I am using the program from David Fanning's site (FIT_ELLIPS) to fit an
> ellips to edge points detected from profiles but the fitted ellips seems to
> be bigger than the supplied data. Anyone that can help?

(a) you just dumped a big uuencoded file into the newgroup. Why?

(b) you uuencoded the text edges.pro file too. Why?

(c) It was difficult to get your script to work. There was no
documentation. Depending on where I clicked, I got different results,
I suppose I am supposed to click the center? The logic of the program
is complex enough that it is difficult to decide what *should* be
happening.

(c) you assumed that Fanning's fit_ellipse function is for fitting
elliptical shells, when clearly the examples show solid elliptical
disks. That script computes the size of the ellipse based on the
moment of inertial of the "blob." Is that what you want?

(d) Have you considered other programs, which actually fit an
elliptical contour to XY scatter data? (such as MPFITELLIPSE)

Craig
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