Abstract
The Simplex algorithm provides a numerically efficient method for the analysis of ellipsometric data on film growth in electrochemical systems. The algorithm finds the complex index of refraction which provides the best fit to a set of data consisting of either Δ and ψ or 
and 
measurements at a series of thicknesses during the growth of a homogeneous film. The way in which the algorithm operates is demonstrated using data on the electrodeposition of polyanaline and the anodization of titanium. Results obtained with and without weighting factors are compared, and a procedure for estimating accuracy is described along with ways of using electrochemical data to aid in the evaluation of goodness of fit.