I think I have a problem for a long winter evening which has been bugging me for some time:

Given a number (large) of unevenly spaced X-Y data points (typically, X data are unevenly spaced independent variable), where the X-Y curve is often non-monotonic and has cusps, how do I create:

1. a new set of X1-Y1 data points with equally spaced X values (preferably using smooth interpolation, but I could live with linear, too)

2. as above, but with an arbitrary number of new data pairs with equally spaced X1 values (range scaling)?

I've looked at Tom Ogilvy's suggested solution (Sep.'03) to find a single interpolated point using the FORECAST, OFFSET and MATCH functions, but I'm still hopelessly stuck.

z.entropic

Answering to myself, and for the benefit of others, I found a wonderful freeware tool to do these tasks, XlXtrFun.xll, an Excel add-on with a number of interpolation, spline and extrapolation tools, as well as much more.

z.entropic

z.entropic

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