[Ifeffit] Re: sigma squared

[Michel Schlegel]

Hello everybody,



> >>>>
>Yes, and when I regenerate the plot, a window pops up to show what range
>I picked, right?  This window does not intersect at 0 on the Xs I
>picked.  I believe the correct x values are written.

I guess I have already seen that and I think it is related to the way the 
edges of the window are calculated. Basically, if you choose a Hamming 
window, set a k-range from, say, kmin to kmax, and a dk window smoothness 
dk, you would notice that the window starts at kmin -dk/2, increases up to 
kmin+dk/2, remains flat up to kmax-dk/2, and then cancels at kmax+dk/2. So, 
basically, the limits for this window are kmin-dk/2 and kmax+dk/2. NOw, it 
seems that Ifeffit is calculating these limits for *any* window.

Incidentally, there's another bug that I observed many times with 
Artemis0.7.12 running on Win2000 (sorry Bruce!): when I perform a 
multi-spectrum fitting and when I set the width of the back-fourier 
transform window for the first spectrum, that window is reproduced for all 
subsequent FTs, whatever the actual R-range I choose for these FTs 
(example: R-range for EXAFS_1 is 1-3 Å (dk = 0 to avoid the problems at the 
limits), R-range for EXAFS_2 is 1-4 Å; the window ploted all along the FT 
for EXAFS_2 is 1-3 Å).
Because I ususally use the same R-ranges for multispectral fitting, I 
didn't care much, but I guess this could be a problem in the future (i.e., 
what actual R-range is used for EXAFS_2?...)

Best regards,

Michel Schlegel
-- 
Michel Schlegel
Commissariat à l'énergie atomique
CEN de Saclay, DEN/DPC/SCP/LRSI
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