[Ifeffit] combining marked groups

[Bruce Ravel]

On Wednesday 04 February 2004 01:40 pm, dmc at pdx.edu wrote:
> Ifeffit Dudes,
>
>      I've tried to plot several groups together in Athena and then saved
> them together under "Save Marked Groups---chi(k)."  It seems to work fine,
> but then when I try to open it up in Artemis I can't do anything.  If I try
> to graph something, it closes.  I can't do a fit b/c there are no
> parameters.  My question is this: how can I average and then fit several
> data files?

Dan, Dude!

You have hit upon a serious problem in the interaction between the two
programs.

You want to save several chi(k) spectra to a single file and then use
Artemis to fit one or more of those spectra.  That is a reasonable
thing to want to do.  Sadly, it is not possible in the current version
of Artemis.

Here is what you should do instead:  Save each chi(k) spectra that you
may want to analyze to an individual file using the File menu entry
that says "Save chi(k)".  This will save a two column data file that
Artemis will have no trouble importing.  You will then have one file
for each of these spectra.  In Artemis, you can use the feature for
*changing* the current data file when you want to switch between
them.

I originally included the "Save marked groups" thing in Athena for the
sake of exporting many spectra from Athena into a plotting program
like Kaleidagraph or XMGrace.  In that case it is convenient to have a
single file with many spectra rather than many files.

For some completely inexplicable reason, it never occured to me that
someone would want to use the marked-groups output file in the manner
that you want.  Interestingly, you are not the first person in the
last week to point this out to me.

So, in the short term, you will have to use Athena to write out
individual data files.  I will address this issue in the next version
of Artemis.

Thanks for posting that message!
B

P.S.  It may not be entriely clear, but you can certainly merge data,
then save the merged spectrum to an individual file without saving any
of the data that went into the merge.  That is, you can write data
groups to output files even when there is not an input file associated
with the data group (as would be the case for a merged spectrum).


-- 
 Bruce Ravel  ----------------------------------- ravel at phys.washington.edu
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