[Ifeffit] Re: I should be able to find this somewhere...

matthew marcus mamarcus at lbl.gov
Mon Jan 16 01:25:37 CST 2006

The background of this is that I'm running Artemis on Windows, and I get some odd things happening
when I select Display Residuals.  The residual often shows as bigger than what's being fit.  At first, I
thought that maybe it was being amplified by some factor in order to display better, but then I realized that
the behavior I'm seeing is inconsistent with that.  For instance, the residual coincides with the data
at R greater than where the last fit path peters out.  It's almost as if I'm seeing |fit+data| and not |fit-data|.

Matt Newville wrote:
> Hi,
> Maybe I missed an important part of the discussion, but that won't
> stop me from sticking my nose in...
> > > By what factor is the residual multiplied when plotted in Artemis?  I can't
> > > find that figure quoted.
> > >       mam
> >
> > The residual is saved in k-space and Fourier transformed.
> ... which ought to be the same as taking the residual of chi(R).
> What's typically plotted (with Artemis and everywhere else) is
> |chi(R)|.  When plotting the magnitude like this and selecting "show
> residual", the magnitude of the residual is shown:
> |chi_data(R)-chi_fit(R)|, not the invidiual differences of real and
> imaginary components.
> --Matt
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