Introduction - If you have any usage issues, please Google them yourself
Uses: third-order spline interpolation (first order derivative boundary condition) format: m = maspline (x, y, dy0, dyn, xx), x is the node vector, y for the data, dy0, dyn left and right ends of points a derivative, if xx default, then the output of each node of the of a first derivative values,, m for the third-order spline interpolation xx