[Ifeffit] Using parameters in Artemis

Bruce Ravel bravel at anl.gov
Thu Mar 8 10:13:08 CST 2007

On Wednesday 07 March 2007 22:19, David Weedon wrote:
> After I hit the "Guess" button I cannot find the parameter "dr" on
> the list.  Am I correct in assuming that "dr" is some kind of
> reserved parameter name that should not be used in equations?

That's correct.

"dr" is one of Ifeffit's so-called "program variables".  It is usually
ok to use a program variable name as the name of a parameter in a fit.
Sometimes it's not.  When I first discovered a situation where it was
a bad idea to use a progarm variable name as a named fitting
parameter, it took me a long time to troubleshoot the problem.  So I
decided that the best solution was to make Ifeffit's program variable
names be reserved words in Artemis and to force you to select
different words to use as the names of your parameters.

I suppose this is an inconvenience (or possibly a freedom-of-speech
issue!), but if you just get in the habit of typing "delr" instead of
"dr", I think you'll manage.

>From the Ifeffit document on the topic of program variables:


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

 Molecular Environmental Science Group, Building 203, Room E-165
 MRCAT, Sector 10, Advanced Photon Source, Building 433, Room B007

 Argonne National Laboratory         phone and voice mail: (1) 630 252 5033
 Argonne IL 60439, USA                                fax: (1) 630 252 9793

 My homepage:    http://cars9.uchicago.edu/~ravel 
 EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/

More information about the Ifeffit mailing list