[Ifeffit] doubts

Bruce Ravel bravel at anl.gov
Thu Nov 10 08:28:39 CST 2005

On Wednesday 09 November 2005 22:52, Carlo Segre wrote:
> Click to the Interpretation tab and select "Guess, Def, Set" in the
> middle pane.  YOu should see all the variables that are defined.  My guess
> is that you have "dr" instead of something like "delr".  Change the name
> to "delr" and then click on the individual paths and change any occurence
> of "dr" to "delr".

Hi folks,

It's even easier since the October 2005 release of Artemis.  On the
"Guess/Def/Set" page, there are all sorts of goodies in the menu that
pops up when you right-click on a parameter.  One of those goodies
says "Change name of <parameter> globally".  This will prompt you for
a new name and change all instances of that parameter on the
Guess/Def/Set page and on all path pages.  In short, it automagically
does all the tedious work that Carlo suggested.

As for this message, which is also new in Artemis, perhaps I should
explain in more detail.

  This parameter uses a name which has special meaning in Ifeffit:
  You must change this parameter name before attempting to fit.
  One common example of this sort is a variable named "dr1", which
  should be changed to something like "dr_1" or "drone". 

I had a bug report a couple of months ago about very confusing
behavior for which hitting the big green button twice in a row would
produce different results.  Very weird.  The problem turned out to be
a parameter name collision.  That is, one of the guessed parameter in
that fit had the name of a word that has special meaning in Ifeffit.

I was very confused by this behavior in that I had trouble
understanding the exact conditions in which this problem was
triggered.  At the time, it seemed as though the most prudent solution
was to disallow all of Ifeffit's reserved words as possible parameter
names.   So now, if you choose one of those words as a parameter name,
Artemis will refuse to run the fit and insist that you change that
parameter's name.

Since I didn't want to make people do all the tedious work that Carlo
described, I wrote the global change function.

Upon re-reading that error message, I agree that it isn't very clear.
Hopefully this email helps clear up the water.


 Bruce Ravel  ---------------------------------------------- bravel at anl.gov

 Molecular Environmental Science Group, Building 203, Room E-165
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 Argonne National Laboratory         phone and voice mail: (1) 630 252 5033
 Argonne IL 60439, USA                                fax: (1) 630 252 9793

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