Hi,
I compared the background subtracted data of my code with the data I
got with Athena and with my code the data always looked as if the
spline clamps did not work, since the chi(k) curve was diverging at
the border at high k-values...
However since you said the syntax is correct I tried it again today
with a new script and now it works fine so probably there was some
other stupid error.
So sorry for bothering you and thanks for the answer which was very
helpful :),
Jan
Zitat von Bruce Ravel :
On Monday 07 December 2009 05:37:41 am you wrote:
Hi Bruce,
I have a question concerning the spline clamps in ifeffit. Is there
any possibility to set them directly in the spline() command? I tried
to do it with spline(..., clamp1=0, clamp2=24,...) but it did not work
and by default both spline clamps seem to be zero. Unfortunately I
found nothing about it in the reference guide either. So how can I
configure the clamps in the Ifeffit code?
Thanks and kind regards,
Hi Jan,
I am CCing this to the Ifeffit mailing list, which is the better place
to ask a question of this sort. I was out of town all of last week --
had you sent this to the mailing list rather than to me directly, you
probably would already have received an answer.
You seem to have the syntax correct. That is, if you follow along in
Athena's Ifeffit buffer, you see that "spline(..., clamp1=0,
clamp2=24,...)" is exactly what she does. Anything you see in the
Ifeffit buffer should be directly transplantable to an Ifeffit
script. Indeed, that is the very purpose of making the Ifeffit buffer
available to the user.
So, what do you mean that the clamps both seem to be zero? How do you
know that? Can you show us an example data file and a short example
ifeffit script that demonstrates the problem? It is quite possible
that changing the clamp strength will have no significant impact of
the background removal. To refresh my memory as I am writing this
email, I loaded an iron foil spectrum into Athena. Indeed, changing
clamp 2 has little impact on the background removal. But I know from
experience that, in general, it does.
Just to tell the whole story, I'll point out that the numeric values
of the clamp strengths in Athena are configurable. If you go to Edit
preferences, then open the clamp group, you will be able to assign new
values to the 5 named clamp strengths.
HTH,
B
--
Bruce Ravel bra...@bnl.gov
National Institute of Standards and Technology
Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2
Building 535A
Upton NY, 11973
My homepage:http://xafs.org/BruceRavel
EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/
--
Dipl.-Phys. Jan Stötzel
Fachbereich C / Physik, Bergische Universität Wuppertal
Gaußstr. 20, D-42097 Wuppertal, Germany
E-mail: j.stoet...@uni-wuppertal.de
phone: +49 202 439-3105, fax: -3101, secretary: -3102
http://hydrogen.physik.uni-wuppertal.de/index.html
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