[Ifeffit] Output of data fit in k-space from current version of Artemis

Bruce Ravel bravel at bnl.gov
Wed May 27 14:43:55 CDT 2015

I should also say that I have never seen this problem except in the 
project file Rosalie sent to me.  I cannot reproduce it with any of the 
project files I have lying around here in my office.

It seems possible -- maybe even likely -- that few other Artemis users 
are seeing this problem.


On 05/27/2015 03:41 PM, Bruce Ravel wrote:
> Hi Rosalie,
> After spending some time with this, I agree that there is something
> very wrong that manifests itself when you attempt to save the data+fit
> file in k-space.
> The executive summary is that there is a problem deep under the hood
> with the k-grid that Artemis uses for the fitted function.  The fitted
> function is not wrong -- but there is a confusion regarding the
> k-grid.  For reasons of how Artemis does it's various chores, this is
> manifested when saving the data+fit file in k, but it is not
> manifested when making certain kinds of plots.  That is, as you
> noticed, the plot looks sensible but the data+fit save file is incorrect.
> I have a work-around for you while to try I continue to puzzle over
> this one.  Download a copy of this small text file:
> https://raw.githubusercontent.com/bruceravel/demeter/master/lib/Demeter/templates/fit/ifeffit/residual.tmpl
> On your computer, overwrite this file:
>    C:\strawberry\perl\site\lib\Demeter\templates\fit\ifeffit\residual.tmpl
> preserving the file name.
> Rerun your fit, then try saving the data+fit output file.
> Let me know if that works for you.  Hopefully I will figure out the
> underlying problem.  If not, it will be good to know if this crude fix
> works for you.
> Cheers,
> B
> On 05/26/2015 09:18 AM, Bruce Ravel wrote:
>> On 05/25/2015 08:37 PM, Rosalie Hocking wrote:
>>> If I go to the Artemis data window and go Data “save data and fit as” it
>>> doesn’t seem to match up with the simulations on the window.
>> Hi Rosalie,
>> I don't see a problem.  In the submenu you mention, there are options
>> for saving data and fit in k-space with various different k-weightings.
>>   When I select the same k-weighting that I am currently using in the
>> plot, save the file, then replot, the data -- it looks the same to me.
>> I hate to be the jerk who says "have you considered this thing which is
>> plainly obvious?" ... but ... are you sure that you are saving the data
>> with the same k-weighting as the plot?
>> Also, I just want to point out that the k-weighted data are in column 2
>> of that file and the k-weighted fit is in column 3.
>> B

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

  National Institute of Standards and Technology
  Synchrotron Science Group at NSLS-II
  Building 535A
  Upton NY, 11973

  Homepage:    http://bruceravel.github.io/home/
  Software:    https://github.com/bruceravel
  Demeter:     http://bruceravel.github.io/demeter/

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