Non-negative exponential splines (Q1110979)

One aspect of shape-preserving spline-interpolation is to guarantee the positivity of an interpolant when the given data are positive. Two strategies to determine the corresponding tension parameters of an exponential spline interpolant are discussed. First, a nonlinear constrained optimization method is considered. The second method gives an a priori estimate of the tension parameters. Several numerical examples are given. In the reviewer's opinion, simple rational splines would be more suitable and more effective to solve the given problem.