It should be 2*(Delta k)*(Delta R), without the +2, but as a floating point number. That is, it is deliberately conservative. I believe the subtle difference you see (that is why the value is 27.06 instead of 27.5) must be due to rounding of the R values on to a discrete grid.

On Oct 10, 2011 9:35 AM, "George Sterbinsky" <GeorgeSterbinsky@u.northwestern.edu> wrote:

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@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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