[Ifeffit] Artemis fitting k-weight

[Bruce Ravel]

On Friday, September 16, 2011 05:48:19 pm George Sterbinsky wrote:
> Hello,
> 
> When fitting data in Artemis with the "other k weight" box checked and the
> kw = 1, 2, or 3 boxes unchecked, I find that the log file lists "k-weight =
> 1, kw", where kw is the value I entered into the "other k weight" text box.
> If I choose 0 as the other k weight, then the log file lists "k-weight =
> 1". Is it possible to run a fit in Artemis using only a k-weight of
> something other than 1, 2, or 3?

George,

You have found two problems in the old Artemis, both have to do with
the reporting in the log file but *not* with the fit.

When I do a fit in Artemis with the k=2 and other buttons ticked and
with the value of the other k-weight set to 0, the log file reports
the k-weight incorrectly as being only 2.  However, the call to the
"feffit" in the Ifeffit buffer looks like this:

  feffit(1-14, group=data0_fit, chi=data0.chi, k=data0.k,
         kweight=2.00, kweight=0.00,  rmin=1.427, rmax=5.065,
         kmin=2, kmax=18.338, dk=1, kwindow=kaiser-bessel,
         fit_space=R, do_bkg=no, data_set=1, data_total=1)

As you can see, both values of k-weight were used even though only
kw=2 was reported.

With only the other button checked, the log file reports:

    k-weight            = 1,0.5

however the Ifeffit buffer reports:

  feffit(1-14, group=data0_fit, chi=data0.chi, k=data0.k,
         kweight=0.50,  rmin=1.427, rmax=5.065, kmin=2,
         kmax=18.338, dk=1, kwindow=kaiser-bessel, fit_space=R,
         do_bkg=no, data_set=1, data_total=1)

i.e. the fit was performed with only the other k-weight.

So the answer to your question is "yes, but it will be reported
incorrectly in the log file."

I have not explored this issue in the new Artemis, but if is exists it
will be fixed before the next Demeter release.

Regards,
B

-- 

 Bruce Ravel  ------------------------------------ bravel at bnl.gov

 National Institute of Standards and Technology
 Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2
 Building 535A
 Upton NY, 11973

 My homepage:    http://xafs.org/BruceRavel
 EXAFS software:  http://cars9.uchicago.edu/ifeffit/Demeter