On Sun, May 24, 2015 at 1:50 PM, Bruce Ravel <bravel@bnl.gov> wrote:

Hi,

Everything in the discussion between Eugenio and Matt is stuff I agree with, except ...

When I rewrote Artemis, one of the motivations was that I wanted to write my own pathfinder rather than to continue using the one in Feff. My main motivation was fuzzy degeneracy (http://bruceravel.github.io/demeter/artug/extended/fuzzy.html) plus I wanted to correct a few other things I saw as shortcomings.

When I was writing it years ago, I didn't immediately see an easy way to consider polarization correctly while also doing fuzzy degeneracy correctly.  I have since figured that out, but years went by and only one person ever asked me about polarized feff calculations in Artemis. So I never implemented it.

It's a funny thing, when you wait for a bus, none comes, then two show up at once.  A month ago, I was asked about polarization in Artemis, and now Eugenio brings it up!

Polarization works (although it needs testing) in the very latest code in github.  But I did that work since the last time I built a Windows installer.  Ellipticity does not yet work (in Artemis -- it works just fine in Feff, but Artemis does not deliver the ellipticity-dependent calculation to the user).


You mean Artemis wasn't creating a POLARIZATION card?   But one can just go in and add that the the Feff.inp anyway, no?   The feff.inp file is editable before running Feff with Artemis all the time, right?  That should be independent of pathfinder.  Or do you mean something else? 
 
Anyway, I will try to find a few hours this week to build a new Windows installer, which will included the ability to consider linear polarization.


> Artemis used to make this very easy (sum paths without fitting),  but
> I don't recall how to do this in the latest version.

Still is easy.  Well, I think it is.  YMMV :)

http://bruceravel.github.io/demeter/artug/plot/vpaths.html


I understand VPaths, I think.    But I meant simply "sum these paths applying the current parameters, without fitting".      That used to be very, very simple and I always find it useful and instructive for exploring the contributions from different paths.  Now it seems I have to set all values to "set", then change them to "guess" to really do a fit.   Am I missing something?

--Matt