how are piecewise cubic bases constructed? how do cubic polynomials make up bases how are piecewise cubic bases constructed how are cubic bases constructed how are a square base and spline base constructed how are piecewise cubic polynomials constructed how are piecewise spline bases constructed how are piecewise cube bases constructed how are piecewise cubic polynomials constructed how are piecewise spline bases constructed? how is the basis for an x-y base constructed? how are piecewise cubic polynomials constructed how are piecewise cubic polynomials constructed how are piecewise cubic polynomials constructed how are cubic bases constructed how are piecewise cubic spline bases constructed? how are piecewise cube bases constructed? how are piecewise cubic polynomials constructed? how is a cubic spline base constructed how are piecewise cubic spline bases constructed