Polynomial regression

[AlanMiller]

I'm wondering if XL 2003 has the capability to fit very high degree polynomials to X-Y data. For instance, if I have 100 data points, is it possible to calculate coefficients for a polynomial of degree 99? If so, a starting point ultraquick tutorial would be appreciated.

Alan

[HansV]

No. You'd need to use LINEST with 1, x, x^2, x^3 etc. as x variables ("known x-es"). The maximum number of x variables supported is 16, and even then the results would probably not be very dependable. This corresponds to a maximum degree of 15.

[AlanMiller]

OK, I think I can sort that with code. How about plotting the result as a smooth curve? Are there any alternatives (add-ins etc.) that are a better choice than Chart Wizard? I'd want to show the original data points and some other points on top of the curve.

Alan

[HansV]

A line chart or scatter chart can draw a smooth line, and you could use another series that only plots markers, no line, for the individual points.

[AlanMiller]

A line chart or scatter chart can draw a smooth line, and you could use another series that only plots markers, no line, for the individual points.

Alan