[Ifeffit] merging data

[Bruce Ravel]

I agree that you have uncovered an edge case where my merging
algorithm does something unexpected.  Figuring this out and fixing it
is nowhere near the top of my list of priorities.  I think I would be
happier flagging an error when the user sets a zero-length range for
the pre- or post-edge lines.

Athena is not intended to be a generic data processing tool.  Its
algorithms are fairly well tested and expected to work when you have
data that nominally resembles XAS data -- that is, some kind of
step-like function, possibly with wiggles above the step.  It has an
algorithm for normalization that makes those same assumptions.

We all eventually go to the beamline and measure something that needs
interpretation, but which is not a step-like function with wiggles.
The solution to that problem is not to expect Athena to miraculously
do what you want.  The solution is to go find the find the right tool
for the job.  Or, if it doesn't exist, write it yourself.

B

On Thursday, December 06, 2012 10:59:55 AM George Sterbinsky wrote:
> Hello,
> 
> I am observing some behavior in (D)Athena that I do not understand, and I
> was hoping someone could explain it to me. I have attached a project file
> to illustrate my question. The first two groups in the file have been
> normalized such that mu(E) and norm(E) are identical. I then merged these
> groups in mu(E) and norm(E), also in the file. Since mu(E) and norm(E) are
> the same for the groups, I would expect the data merged in mu(E) and
> norm(E) to also be identical, but it is not. While it is clear that merging
> in mu(E) is averaging the groups, it seems merging in norm(E) is not. So
> what is merging in norm(E) doing?
> 
> Thank you,
> George


-- 

 Bruce Ravel  ------------------------------------ bravel at bnl.gov

 National Institute of Standards and Technology
 Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2
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