How do you do a "moving 5pt 3rd order fit"?

I want to model the upshift of a curve using a moving 5pt 3rd order fit... Does anyone know how this is done?

Thanks in advance for any feedback you can give me!

Answer 1

[Walter Roberson]

A moving five point third order fit sounds to me like a cubic spline.

[John D'Errico]

No. Not a spline at all.

Answer 2

[John D'Errico]

I'm not sure what upshift means, at least not in context of a manual transmission for a car.

You can use conv or filter to do a moving fit, so a Savitsky-Golay filter of some sort. It depends on what you are looking for.

http://en.wikipedia.org/wiki/Savitzky–Golay_smoothing_filter

If by upshift, you really mean the slope of the curve, I have movingslope posted on the FEX. It alows you to specify the support of the Savitsky-Golay model, as well as the order.

http://www.mathworks.com/matlabcentral/fileexchange/16997-movingslope

[Sy]

Upshift refers to the shape of the curve.