I don't see the behavior you describe when I follow your recipe.
Perhaps it got fixed when I fixed this fellow's issue...?

http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2015-May/012496.html

Of course, the Mac package is a fair bit behind at this point.

B

On 08/06/2015 06:10 PM, George Sterbinsky wrote:
> Hello,
>
> I am writing to report a bug in Athena running on OSX 10.10.4. Here are
> the steps to reproduce the problem. I'm not sure that all steps are
> necessary.
>
> 1. Open Athena and import the attached project, which contains two
> groups that are both marked.
> 2. Change plot range to plot from -30 to 30 eV.
> 3. Select the "deglitch and truncate" window.
> 4. Select group "Ref data.merge".
> 5. In deglitch many points, set margin to 0.05, Emin to -24, and Emax to
> -20.
> 6. Click replot margins.
> 7. Click remove points.
> 8. Click return to main window.
> 9. Click the derivative check box to plot marked groups as normalized
> derivative.
> 10. Click mu(E) button to plot marked groups as derivative of mu(E).
>
> When the last step is done the groups appear to shift with respect to
> each other. One can switch between Normalized and mu(E) and see the
> shift come and go.
>
> Thank you,
> George
>
>
>
> _______________________________________________
> Ifeffit mailing list
> Ifeffit@millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
>


--
  Bruce Ravel  ------------------------------------ bravel@bnl.gov

  National Institute of Standards and Technology
  Synchrotron Science Group at NSLS-II
  Building 535A
  Upton NY, 11973

  Homepage:    http://bruceravel.github.io/home/
  Software:    https://github.com/bruceravel
  Demeter:     http://bruceravel.github.io/demeter/