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Re: Fit a circle ? [message #32799]

Fri, 08 November 2002 03:16

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

<zeschke@bessy.de> writes:

> is there a simple way to fit a circle (a radius) on a set of x,y-points,
> which are only come from a small part of the circle ?
> I want to use the mpfitellipse.pro-Routine (Craig Markwardt).
>
> I tried this without success :
> ;;;;;;;
> ; Construct a set of points (should be a part of a circle)
> x= dindgen(100)-50.
> y= x^2 *1e-8 + 1e-6*randomn(seed, 100)

I'm confused. Even with the noise removed, this is not the equation
for a circle, but a parabola instead (or perhaps a tiny edge of an
ellipse in some limiting case). If you are trying to fit parabola,
then you should use MPFITFUN or MPFITEXPR.

Craig

--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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Re: Fit a circle ?

By: Craig Markwardt on Fri, 08 November 2002 03:16

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