Fitting multiple spectra simultaneously with Larch
Dear Ifeffit team, I’d like to fit multiple EXAFS spectra simultaneously in Larch using several common parameters/relative restraints, but have not found a way to do so (yet). I’ve gone through Dr. Matt Newville’s youtube tutorials (generally very helpful), but this topic doesn’t seem to have been covered. Any suggestions? Thanks! Best, Casey Van Stappen ------------------------------------------------------------------------ Dr. Casey Van Stappen University of Texas at Austin Robert A. Welch Hall, 4.318 2350 Speedway Austin, TX 78705 USA Phone: +1 (512) 775-2658 E-mail: casey.vanstappen@austin.utexas.edu
Hi Casey, You can find some examples on the webpage https://xraypy.github.io/xraylarch/xafs_feffit.html#example-1-simple-fit-wit... . Have a nice evening! Best, Harry ------ Harry Zhang Eindhoven University of Technology 5612 AZ, Eindhoven, The Netherlands On Mon, Sep 12, 2022 at 6:30 PM Van Stappen, Casey M < casey.vanstappen@austin.utexas.edu> wrote:
Dear Ifeffit team,
I’d like to fit multiple EXAFS spectra simultaneously in Larch using several common parameters/relative restraints, but have not found a way to do so (yet). I’ve gone through Dr. Matt Newville’s youtube tutorials (generally very helpful), but this topic doesn’t seem to have been covered. Any suggestions? Thanks!
Best,
Casey Van Stappen
------------------------------------------------------------------------
Dr. Casey Van Stappen
University of Texas at Austin
Robert A. Welch Hall, 4.318
2350 Speedway
Austin, TX 78705
USA
Phone: +1 (512) 775-2658
E-mail: casey.vanstappen@austin.utexas.edu
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Hi Casey, Sorry for the late reply - I see that you asked this question 2 weeks ago - I think I got the same question from someone else by private email the same day.... I have had this question several times this summer. Anyway, sorry for missing this. Larch can definitely fit multiple spectra at one time, co-refining parameters. An example of fitting 3 datasets (Cu K edge at 3 temperatures) is at https://github.com/xraypy/xraylarch/blob/master/examples/feffit/doc_feffit3.... That is, you create several "Feffit datasets". Each of these has a group for the chi(k) data, a "transform" that gives the Fourier (or Wavelet) Transform configuration and the fitting ranges, and a list of Feff Paths. Different data sets can use the same transform and reuse Feff Paths. You will also have a Parameter Group with all the variables and other Parameters used to calculate the Path Parameters for each Feff Path. Anyway, yes, Larch can definitely fit multiple datasets. But: The XAS Viewer GUI does not currently (yet?) support this -- it helps build a model, do the fit, and inspect the results for one dataset. It also helps write out the larch script to do the fit. One approach could be to use that: use the GUI for "simple stuff" and interactive data exploration, but use a script for more complicated and involved analyses. I'm not opposed to adding fitting of multiple data sets in the XAS Viewer GUI, but implementing it in the current GUI framework seems challenging (it was definitely challenging for Artemis too). I've heard some good suggestions, but I'd be curious to hear (either here or via private email) what others would like to see or suggest. I guess that question really extends to other aspects of Larch and XAS Viewer: if there are features, analysis approaches, or GUI tools that you think could be better, let me know. On Mon, Sep 12, 2022 at 11:30 AM Van Stappen, Casey M < casey.vanstappen@austin.utexas.edu> wrote:
Dear Ifeffit team,
I’d like to fit multiple EXAFS spectra simultaneously in Larch using several common parameters/relative restraints, but have not found a way to do so (yet). I’ve gone through Dr. Matt Newville’s youtube tutorials (generally very helpful), but this topic doesn’t seem to have been covered. Any suggestions? Thanks!
Best,
Casey Van Stappen
------------------------------------------------------------------------
Dr. Casey Van Stappen
University of Texas at Austin
Robert A. Welch Hall, 4.318
2350 Speedway
Austin, TX 78705
USA
Phone: +1 (512) 775-2658
E-mail: casey.vanstappen@austin.utexas.edu
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
-- --Matt Newville <newville at cars.uchicago.edu> 630-327-7411
participants (3)
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Andy Zhang -
Matt Newville -
Van Stappen, Casey M