[Ifeffit] Importance and Edge Step

Bruce Ravel bravel at anl.gov
Mon Jun 6 10:03:20 CDT 2005

On Monday 06 June 2005 09:27, Gerrit Schmithals wrote:
> How do I implement more than 4 references? There is a box for entering
> the number but it does not enlarge the reference-list as I expected it
> to do.

All of this is explained in the doc page for the LCF dialog.  (That
is, I think I explained it all there.  It may be [is?] poorly
explained ....;-)

The length of the standards list is set in the preferences dialog.
The relevant parameter is linearcombo->maxspectra. 

The huge new feature in the LCF dialog is what I am calling
combinatoric fitting.  Suppose you have 4 standards in the list in the
LCF dialog.  You can press the button that says "Fit all possible
combinations" and Athena will cycle through all fits of 2, 3, or 4 of
the standards to your data.  Now suppose that you have 11 standards in
the list.  Cycling through all possible combinations would be
extrememly time consuming.  What's more, the fits involving many
standards probably wouldn't be very believable in most situations.  So
you can tell Athena to limit the order of fits.  By setting the widget
below the list to 4, you tell Athena to fit all possible combination
of 2, 3, or 4 out of the 11 possible standards.  (FWIW, that's 550
fits -- it takes about 12 minutes on the computer I am sitting at
right now.)

There were also some problems in how the interpolating of the
standards onto the energy grid for the fit was done in certain
situations in previous versions of Athena.  Interpolation should be
working properly now.


 Bruce Ravel  ----------------------------------- bravel at anl.gov  -or-
						  ravel at phys.washington.edu
 Environmental Research Division, Building 203, Room E-165
 Argonne National Laboratory         phone and voice mail: (1) 630 252 5033
 Argonne IL 60439, USA                                fax: (1) 630 252 9793

 My homepage:    http://feff.phys.washington.edu/~ravel 
 EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/

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