# Fitting and Ellipse to a set of data points in Mathcad.

I would like to fit an ellipse to a set of data points in Mathcad and afterwards plot it. Searching the net, I stumbled on to Mike Shaw's post, which answers 75% of my question: See Plotting an Ellipse after an Ellipse Fit

Could someone enlighten me how to determine the co-effiecients and centre of the ellipse, in Mathcad, using the fitting algorithm; this for formula: $ax^2 +bxy+cy^2 +dx+ey+f=0$

Simon

• If you want an ellipse (as opposed to some other type of conic section curve), then you have to constrain the coefficients to ensure this. Nov 20, 2015 at 13:21

• Thanks for the answer... I was under the assumption that Mike used some sort of fitting functionality within MathCAD like "genfit" with just $ax^2+bxy+cy^2+dx+ey+f=0$ and the data points as input. Enlightened by your answer I successfully implemented the algorithm of the paper. Nov 25, 2015 at 7:51