-spline representation of interpolating and smoothing quadratic spline
Some basic theorems and formulae (equations and inequalities) of several areas of mathematics that hold in Bernstein spaces are no longer valid in larger spaces. However, when a function f is in some sense close to a Bernstein space, then the corresponding relation holds with a remainder or error term. This paper presents a new, unified approach to these errors in terms of the distance of f from . The difficult situation of derivative-free error estimates is also covered.
Continuity conditions for a biquadratic spline interpolating given mean values in terms of proper parameters are given. Boundary conditions determining such a spline and the algorithm for computing local parameters for the given data are studied. The notion of the natural spline and its extremal property is mentioned.