Hello,
> I hope you don't mind that I am sending my responses to your questions
> to the Ifeffit mailing list. They seem of sufficiently general
> interest that I think the Ifeffit list would be interested.
I don't. :)
> MS> Another detail which kind of puzzles me: whenewever I use a
> MS> Kaiser-Bessel window and increase the weight, the *plotted*
> MS> limits of the apodization window shift away from the positions
> MS> defined in the command window (e.g., for positions set to 2 and
> MS> 13 Å-1 in the command window and a weight dk = 1, the plotted
> MS> apodization limits are shifted to 1 and 14 Å-1).
>
> I am a bit confused by the numbers you give in that they are not
> consistent with what I observe when I make a plot displaying a
> Kaiser-Bessel window. Here is what I observe:
>
> For a window defined by kmin=2, kmax=18, and dk=2, the first
> non-zero value of the window is at k=1 and the last non-zero value
> is at k=19. In general terms, the first non-zero value of the
> Kaiser-Bessel window is at kmin-dk/2 and the last is at kmax+dk/2.
OK, I wanted to make the distinction between the first and last non-zero
values as they *appear* in the graphic window, and the numerical values as
stored as internal values in the software. I assumed that these values were
not the same. This assumption, but was -partly - justified by the wollowing
reason: If I keep kmin and kmax constant and increase dk, I increase the
k-range covered by the K.B. window, and this should result in an increase of
the number of independent points. What I observe is that the number of
independent points calculated by artemis is *not* affected by dk, suggesting
that the FT range remains limite to [kmin, kmax].
> The bottom line is that you may want to set kmin a bit higher so that
> kmin-dk/2 is at the point where you want the window to start. Note
> that setting dk to 0 is probably *not* what you want to do, although
> it is probably worth doing so just once to see what happens to the K-B
> window.
I did: the first and last non-zero values plot exactly at kmin and kmax.
> MS> A final 'cosmetic' suggestion: would it be possible in future
> MS> versions of artemis, to plot both the amplitude and real part, or
> MS> amplitude and imaginary parts of experimental and simulated
> MS> chi(R) together?
>
>
> You are not the first person to ask for this, Michel, but the last
> time this came up, Artemis was much less far along.
Sorry for being late...
> So, let me put it up to discussion among the folk on this mailing
> list. What should Artemis do?
>
> 1. Allow the user to select one or more parts of chi(R) (or chi(q)
> for that matter) and plot each of those parts for each of the
> things selected in the "Paths" list.
> 2. Allow the user to somehow specify which parts of chi(R) to plot
> for the data, the fit, and each path individually. (This would
> make the interface somewhat more complex.)
> 3. Continue to work exactly as it works now.
> 4. Something else entirely.
Basically in a simulation, both the amplitude and the phase of selected
paths may be (shoud be?) compared. Therefore, I would select (1) (but let
me reiterate that this is not a priority to me).
Thanks in advance, and happy new year,
Michel Schlegel
