# [Ifeffit] number of independent points

George Sterbinsky GeorgeSterbinsky at u.northwestern.edu
Mon Oct 10 09:35:12 CDT 2011

```Hello,

Since I haven't received a response to my previous question, I just wanted
to make sure I asked it clearly. To elaborate, I am attaching a log from
Athena. The log file lists:

"Independent points          =      27.057617188"

If I attempt to reproduce this result using the equation in the feffit
document, I find

Nidp = { [2*(kmax - kmin)*(Rmax-Rmin) / pi] + 2} = { [2*(14 - 0.5)*(4.2 -
1.0) / pi] + 2} = 29.50197417,

where I have used the k-range and R-range in the log file as kmax, kmin,
Rmax, and Rmin.

Can someone explain to me why may calculation does not reproduce the number
given for "independent points" in the log fie?

Thank you,
George

On Fri, Oct 7, 2011 at 1:04 PM, George Sterbinsky <
GeorgeSterbinsky at u.northwestern.edu> wrote:

> Hello,
>
> I am wondering what values Artemis/feffit use for kmax and kmin when
> calculating the number of independent points (Nidp) for a fit done in
> R-space, where according the feffit document, Nidp = { [2*(kmax -
> kmin)*(Rmax-Rmin) / pi] + 2}, and kmax and kmin define the fitting range. I
> have tried using the Fourier transform range for kmax and kmin, but this
> does not give agreement with the value of Nidp reported by Artermis.
>
> Thank you,
> George
>
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