CODEWITHSUNDEEP
matlabmachine-learningregressionlinear-regression
Akshay Jain
Akshay Jain

Reputation: 904

Best fit circle with fix center in MATLAB

I have a few points circle is passing through and I want to find the radius of the best fitting circle with center fixed at the origin.

CircFit doesn't allow specifying the center explicitly and I need it fixed at origin.

Upvotes: 0

Views: 719

Answers (1)

jodag
jodag

Reputation: 22204

To post my answer from the comments.

The distance from a point to the nearest point on a circle is sqrt((x-xc).^2 + (y-yc).^2) - r).^2. The error function for the least squares optimal is then err = sum((sqrt((x-xc).^2 + (y-yc).^2) - r).^2).

Taking the derivative of err with respect to r and setting it to zero, then solving for r gives you the solution r = mean(sqrt((x - xc).^2 + (y - yc).^2)).

As a MATLAB function this could be written as

function r = circfitFixedC(x,y,xc,xy)
    r = mean(sqrt((x - xc).^2 + (y - xy).^2));

Upvotes: 1

Related Questions