Den Hertog, Dick; de Klerk, Etienne; Roos, J. - Tilburg University, Center for Economic Research - 2000
In this paper we prove the counterintuitive result that the quadratic least squares approximation of a multivariate convex function in a finite set of points is not necessarily convex, even though it is convex for a univariate convex function. This result has many consequences both for the field...
