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Math Forum » Discussions » sci.math.* » sci.math.num-analysis.independent

Topic: Radius algorithm
Replies: 1   Last Post: Dec 6, 1996 7:02 AM

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Peter Spellucci

Posts: 630
Registered: 12/7/04
Re: Radius algorithm
Posted: Dec 6, 1996 7:02 AM
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solve it as an orthogonal distance problem. computing the distance**2 of the
points from the asumed circle and summing up you obtain a ordinary
least squares problem in three unknowns. even easier: plug your data
in odrpack (from netlib). they even have a driver for orthogonal distance
regression for ellipses (driver2).
hope this helps
peter
original posting:
I have a number of x,y data points that form an arc of constant radius.
Do you know a good technique for finding the center and radius of the
arc?
I've tried the following, but I'm not sure of it's reliability:
take first data point, find line running through point but also tangent
to the arc, take second data point and find line tangent again.
Normalize both lines and find the intersection. This will give me the
center, from here the radius is easy.

Do you have any suggestions?
Thanks, Marc





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