Cubic Spline Question

[gideonsimpson]

How do the cubic splines interpolants that this package produces compare to classical textbook cubic splines? That is to say, is the package implementing "natural" boundary conditions? "not-a-knot" boundary conditions? Something else?

[kbarbary]

It implements basis splines (b-splines).

I believe it implements "not-a-knot" boundary conditions. It doesn't do "natural" (2nd derivative = 0) conditions. I'm not entirely sure about this though and would have to comb through the Fortran source code to really be sure.