1. This type of spline is for high Technical/Scientific works.
2. It roams around points, governed by the vector of knots.
3. Not easy to manipulate: trial/error for best fit.
4. Most likely it will crash Smath ... save a working copy.
5. Supports indirectly integration [via Smath ainterp typical].
6. Supports infinitesimal derivative ...
at this point: you may adjust the vector of knots from
visual inspection of the derivative.

Jean

Spline0 Quadratic Lagrange Knots.sm (38 KiB) downloaded 74 time(s).

... refactored for publishing.
Spline Lagrange of higher order exist, not conserved.

Jean

Spline0 Quadratic Lagrange Knots.sm (70 KiB) downloaded 66 time(s).