This exercise explores some of the differences between a cubic polynomial and a cubic spline. In this problem the data are: (
1,
1) = (0, 0), (
2,
2) = (1, 1), (
3,
3) = (2, 0), and (
4,
4) = (3, 1).
(a) Find the global interpolation polynomial that fits this data, and then evaluate this function at
= 1/2.
(b) Find the natural cubic spline that fits this data, and then evaluate this function at
= 1/2.
(c) The cubic in part (a) satisfies the interpolation and smoothness conditions required of a spline, yet it produces a different result than the cubic spline in part (b). Why?
(d) What boundary conditions should be used so the cubic spline produces the cubic in part (a)?