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|. mam 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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