You wrote...

>A typical problem for me is interpolating thermistor data.  The thermistor
>curve comes in chart form from the manufacturer, in very un-handy
>increments.  It's quite a complex curve, and I think curve fitting it
>would be a long involved task (unless Excel does this automatically
>somehow? )  Linear curve fitting would be a cinch.   The only way I know
>how to curve fit a nonlinear is, guess at the type of equation to use,
>plot it next to your data, sum the squares of the differences,  then run a
>linear regression on the results and use a Tools:GoalSeek on the results
>to approach the minimum, then guess again at the type of equation to use
>until you like the fit..  It is a time-consuming process, usually.
>
>Is there a more efficient way?

Check out the Mathserv Calculus Toolkit on Vanderbilt
University's website, at:

http://mss.math.vanderbilt.edu/~pscrooke/toolkit.shtml

Selecting "Polynomial Interpolation" brings you to a screen which
allows you to do a least-squares fit of arbitrary order to a set
of given data points.

Enter the data points, specify the order of the polynomial, click
the "FIT" button, and voila: coefficients galore.  Neat.

Dave D.

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