If wi (x) is constructed using the C cubic spline weight function given in Equation (11), then unlike the MLS approximant, a convex approximant with desirable properties on the boundary is obtained. Other choices for mi (x) include compactly supported RBFs, for example the C2 function m(r )=(1 − r )4+(4r + 1)[10], where (·)+ =(·) if the argument is non-negative and zero otherwise.