Interpolation, approximation and the like (alglib package) - page 17

 
Denis Zhivaev #:

And what are the inputs to the X, Y arrays?

Apparently the coordinates of the nodes of the spline

https://www.alglib.net/translator/man/manual.cpp.html#sub_spline1dbuildcubic

 

Yes, point coordinates. I haven't seen a parameter approximated by a spline.

There seems to be a lot of language to use here.