Statistical - Cubic Regression (Cubic Spline Fit) ?

[jonmoore]

When using desktop CAS/statistical packages, I often find that a cubic spline regression provides the best fit, for the data I'm analysing. The TI Nspire includes cubic regression as standard as do Casio calculators such as the CG50 (and its ancestors), and I wondered if there are any great examples of cubic regression on HP calculators.

For smaller data sets, I tend to use the Curve Fitting routines included in SandMath on my DM41x these days (originally found on the venerable AECROM), as this includes a best-fit routine but cubic regression\spline\curve isn't one of the options.

And any of the good routines I've encountered on RPL calculators 48/50 are emulations of the AECROM routines and the story is much the same on the Prime.

I'm sure something exists somewhere in the HP ecosystem. And it may be labelled polynomial regression as this is ultimately the expression describing the spline (be it Quadratic/Cubic/Quartic etc.). But I've not found it on my travels to date.

Any suggestions will be most gratefully received.