Dear Matt,

I will take the time to look into this. I saw the previous thread from yourself 
with the link to the installer and relative information etc.

Many thanks.
Best regards,

Paul Scherrer Institut
Craig Lawley
Forschungsstrasse 111
5232 Villigen PSI

Telefon: +41 56 310 5054

From: Ifeffit [] On Behalf Of 
Matt Newville
Sent: Donnerstag, 2. Mai 2019 04:58
To: XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] Pseudo Voigt crash Athena

Hi Craig,

On Wed, May 1, 2019 at 10:51 AM Lawley Craig Richard (PSI) 
<<>> wrote:
Dear Mailing list,

I have run into an issue with the peak fitting section included in Athena. If I 
include a peak that is a Pseudo-Voigt and then save the project file. Upon 
trying to reopen the same project file, Athena becomes non responsive with the 
error message “PV is not yet implemented”.

This may sound like a broken record, but I strongly encourage you to try Larch 
and the XAS Viewer application for peak fitting of XAS spectra.  The ifeffit 
library is really old (has not been updated in 5 years), not supported, and its 
interface to peak fitting is primitive.

Larch (and the lmfit library it uses) and the XAS Viewer GUI are all supported. 
Peak-fitting of XANES is one feature which I am confident to say is definitely 
better than Athena. I'm willing to take 100% of the blame for this, but 
peak-fitting does not work well in Athena. XAS Viewer has more lineshapes 
including both PseudoVoigt and (true!) Voigt lineshape functions.  It also 
supports better mechanisms for applying mathematical constraints and for 
applying bounds on parameters which can be important for modeling XANES with 
multiple peaks.    lmfit/Larch also provides more and better fit statistics, 
such as reporting FWHM (and its uncertainty) for each peak, and (for XANES) the 
centroid of the pre-edge peaks.  Though not supported directly in the GUI, 
lmfit/Larch does allow one to do a more thorough estimate of uncertainties and 
to use minimization methods other than Levenberg-Marquardt.  My experience is 
that these seem to be not so important for peak-fitting of XANES data, but I 
don't know that this is always the case (and to be clear, there are certain 
classes of "line shape fitting" where these are important).  Like Athena, XAS 
Viewer records all the code actually run making it easy to turn a GUI session 
into a Larch script or Python program to do more detailed analysis or to help 
write analysis scripts for batch processing.

Hope that helps,


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