Datum2D.m

Fits arbitrary-order linear least squares equation to xy data with (optional) automatic outlier ...

Arbitrary-order polynomial datum is fit to and extracted from input xy data. Outliers - defined based either on a non-parametric or mutliples-of-standard deviation criteria - are optionally identified and "set aside". The interative solution proceeds until there are no remaining outliers in the decimated dataset. If the specified fit equation is quadratic, the (linear approximation) circular arc center point xo,yo and radius R are returned, along with the residuals vector, polynomial coefficients, and terminal outlier criterion. Xo,yo, and R are useful as initial guesses for a subsequent "exact" nonlinear (e.g. Levenberg-Marquardt/lsqnonlin) circle fit solution.