Editing Cubic function (section)

==Cubic interpolation==
{{main|Spline interpolation}}
Given the values of a function and its derivative at two points, there is exactly one cubic function that has the same four values, which is called a [[cubic Hermite spline]].

There are two standard ways for using this fact. Firstly, if one knows, for example by physical measurement, the values of a function and its derivative at some sampling points, one can ''interpolate'' the function with a [[continuously differentiable function]], which is a [[piecewise]] cubic function.

If the value of a function is known at several points, [[cubic interpolation]] consists in approximating the function by a [[continuously differentiable function]], which is [[piecewise]] cubic. For having a uniquely defined interpolation, two more constraints must be added, such as the values of the derivatives at the endpoints, or a zero [[curvature]] at the endpoints.