AN ALGORITHM FOR CONSTRUCTING C² SHAPE-PRESERVING OR MONOTONICITY-PRESERVING INTERPOLATING POLYNOMIAL SPLINE

This paper discusses the problem of C² continuous shape- preserving or monotonicity- preserving piecewise polynomials interpolant. A fifth or higher order polynomial piece is constructed between two consecutive data points. By increasing order of polynomial while needing in some intervals, the piecewise polynomials interpolating function is C² continuous and shape- preserving or monotonicity- preserving.