How "circle fit" component make circle from many points?

[TomTom (Tom)]

Origin of interpolated curve/arc

just in case you want to know how Circle Fit works (not sure if its the same), here is one self written approach by using regression analysis (LLS). Works for spheres as well: [FitCircle] [FitSphere] CircleFitLS.gh (4.1 KB) SphereFitLS.gh (14.6 KB)