File Exchange

image thumbnail

Circle Fit (Pratt method)

version 1.0 (2.18 KB) by

Fits a circle to a set of data points on a plane; returns the circle center (a,b) and radius R.



View License

Editor's Note: This file was selected as MATLAB Central Pick of the Week

This is a robust and accurate circle fit. It works well even if data
points are observed only within a small arc. This circle fit was proposed by V. Pratt in article "Direct least-squares fitting of algebraic surfaces", Computer Graphics, Vol. 21, pages 145-152 (1987). It is more stable than the simple Circle Fit by Kasa (file #5557).

Comments and Ratings (9)

hing ho

hello, are you have excel vba version? thank a lot!

Qiliang Lin

very helpful. Thanks!


It works perfectly and helps me so much,thank you.


John (view profile)

Anton Jigalin

tejas harish

can anyone please tell me how to give inputs to circle fit by pratt method.


i need to fit a circle to find the curvature of a line at various points using the radius. can u suggest a way to check my results. Thank u in advance.

Gwen Bailey

Thank you very much for this algorithm. I was looking for an algorithm to fit a small number of data points (around 50) to a small portion of a circle (less than 10 degrees of the outline) and found this one to work perfectly. I had previously been using the Bucher circle fit and found it to be nowhere near as accurate or stable (although it is faster).

Thanks again!

Gwen Bailey

MATLAB Release
MATLAB 6.0 (R12)

Inspired by: Circle fit

Download apps, toolboxes, and other File Exchange content using Add-On Explorer in MATLAB.

» Watch video

Win prizes and improve your MATLAB skills

Play today