After searching for hours, the function GenInterSpline that youa re talking about is exactly what I need! However, I can't seem to get it, as it does not appear to be attached to your post. Can you send it?
I am trying to interpolate a z value from a set of (x,y) data points with a cubic-spline fit. I succeeded in doing this with a 3rd order polynomial regression, but I would like to compare the quality of the fit with a cubic-spline fit. See attached for the data.