Why my fitting curve changes?

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Let's say I have 3 groups of data (X, Y1, Y2). I make the first plot (X vs. Y1) and do a simple line fit; then I repeat these steps for the second plot (X vs. Y2). Now the problem comes: the fitting curve on the first plot simultaneously changes to EXACTLY the curve shown on the second plot. I tried a few times and even set the range in "Analysis-Curve fitting-Data options" for each plot. It didn't help. Making different line fits for individual plots should be quite simple, did I miss something?

Thanks!!
I don't think you have x, y1, y2. I think you have x1, x2, y and you fit y vs x1 and then y vs x2.

The wave created for the fit curve is given a name derived from the Y wave, "fit_". So if you have fit the same Y wave twice you get just one fit curve wave. The solution is to re-name the fit curve wave after the first fit, then the automatically generated wave won't overwrite it.

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

January 23, 2015 at 01:55 pm - Permalink

Hi John,

Big thanks for solving the problem, which has puzzled me for a while!

January 23, 2015 at 08:53 pm - Permalink