[Ifeffit] path-sensitive math expressions
Bruce Ravel
ravel at phys.washington.edu
Fri Sep 5 13:13:44 CDT 2003
Hi Matt,
I have some questions about a subtle detail in ifeffit. It is
possible to make a def parameter which is path sensitive in the sense
that it will evaluate differently for different paths. Any def
parameter which includes reff, eins(), or debye() in its math
expression will be that way.
Here is a simple, if slightly silly, example:
def rrr = reff/10
path(1, feff=feff0001.dat, dr=rrr)
path(2, feff=feff0002.dat, dr=rrr)
Then
show rrr
will report 1/10 the R_eff of the *second* path.
So here are my questions:
1. Are all def parameters reevaluated every time a new path is
evaluated? Or only if the path uses the def parameter in one of
its math expressions? (I think the answer is the former.)
2. Is it possible to ask ifeffit which def parameters are path
sensitive? Of course, I can scan the def parameters at the level
of perl to see if any of them obviously are, but ifeffit might
already know that.
3. If you do
show ss
the value is the value of the last path evaluated. Doing
show @path N
show ss
will indeed display the value of the def parameter appropriate to
the Nth path. Is there another way of forcing ss to be evaluated
appropriate to a desired path?
Thanks,
B
--
Bruce Ravel ----------------------------------- ravel at phys.washington.edu
Code 6134, Building 3, Room 222
Naval Research Laboratory phone: (1) 202 767 5947
Washington DC 20375, USA fax: (1) 202 767 1697
NRL Synchrotron Radiation Consortium (NRL-SRC)
Beamlines X11a, X11b, X23b, X24c, U4b
National Synchrotron Light Source
Brookhaven National Laboratory, Upton, NY 11973
My homepage: http://feff.phys.washington.edu/~ravel
EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/
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