[Ifeffit] one more thing...

Bruce Ravel ravel at phys.washington.edu
Thu Oct 30 10:04:44 CST 2003

Hi folks,

The one very obvious change in how Athena behaves is how it plots
normalized mu(E) spectra.  If you dislike this new feature and would
prefer to always see the normalized data as they were previously
plotted, it is easy to disable by going to the preferences dialog,
selecting the variable Bkg -> flatten, and setting it to false.

Below is the description of this new feature from the NEWS page on my
web site.


1.  FLATTENED DATA. I added a new features for plotting normalized
    spectra which I call flattening.  In short, this works by
    subtracting the linear and quadratic portions of the polynomial
    regressed to the post-edge region of the data from the normalized
    data after the edge.  This has the effect of shifting the
    oscillatory portion of the spectrum such that it oscillates about
    1.  That is, the flattened spectrum is presented with its baseline
    at 0 and it's post-edge at 1.

    This is purely a plotting device and has no impact on the
    calculation of chi(k).  It can be turned on and off for a data set
    using a toggle button in the background removal section of the
    main window.  Whether flattening is on or off by default is
    configurable in preferences dialog.

    Flattening is sensitive to how the post-edge line is chosen,
    particularly in XANES data which have a limited energy range.
    The idea for this feature was blatantly swiped from SixPack.

 Bruce Ravel  ----------------------------------- ravel at phys.washington.edu
 Code 6134, Building 3, Room 222
 Naval Research Laboratory                          phone: (1) 202 767 5947
 Washington DC 20375, USA                             fax: (1) 202 767 1697

 NRL Synchrotron Radiation Consortium (NRL-SRC)
 Beamlines X11a, X11b, X23b
 National Synchrotron Light Source
 Brookhaven National Laboratory, Upton, NY 11973

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

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