[Ifeffit] Fit in R and k space

[Stefano Ciurli]

Hi Scott,

>I'm not sure what you're suggesting--a real simultaneous fit, which somehow
>weights the fit in R-space and k-space to arrive at a single set of
>parameters? Or just two fits in series so that you only hit one button?

first of all let me tell you that the idea of running the fit in 
R-space somehow disturbs my simple mind, considering that the R-space 
depends on the processing parameters (window type and width, weight 
etc). So, I would assume that a fit in k-space would be auspicable. 
Then, I discovered that EXCURV, the competing program at least for 
biological XAS, performs the fit BOTH in R-space and in k-space, and 
I am pretty sure that the parameters it gets are slightly different.

then, yes, I was thinking of two different fits hitting the same 
button (let's say in Diana - or Artemis - instead of having just the 
option of running the fit either in R- or in k-space, one could have 
an additional button telling the program to run both fits)

>In the first case, I'm not sure I see a big benefit considering that the
>weighting scheme becomes in effect another opaque parameter that can be
>used to generate arguments among experts. :)

that I understand, not being an expert... :-)

>In the second case, it seems to me more straightforward just to run the fit
>twice.

OK. probably yes, but if Bruce may think of a slight improvement ... 
it was just an idea

Regards,
Stefano
-- 
____________________________________________

Stefano Ciurli
Professor of Chemistry
Laboratory of Bioinorganic Chemistry
Department of Agro-Environmental Science and Technology
University of Bologna
Viale Giuseppe Fanin, 40
I-40127 Bologna
Italy
Phone:	+39-051-209-6204
Fax:	+39-051-209-6203

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