Hi All, I would like to ask, after a fit (in Artemis) which column in the output file gives the uncertainty for peaks position dR (R+/-dR i.e. 3+/-0.02 Angstroms) ? Is there additional information that could be extracted from wavelet transform ? Thank you. Dimitar
On 10/13/2016 05:17 PM, Dimitar Popmintchev wrote:
I would like to ask, after a fit (in Artemis) which column in the output file gives the uncertainty for peaks position dR (R+/-dR i.e. 3+/-0.02 Angstroms) ?
Error bars are not propagated in Artemis currently. That's something you, the user, has to do using the math expression that relates your variable(s) to the delta R in question. The simplest common case is one where you have guess delr = 0 then later, for some path, reff = 3.0 deltaR = delr In that case, delr is varied and the path length is 3.0 + delr. Propagating the uncertainty in this case is trivial: delta( 3.0 + delr) = delta(3.0) + delta(delr) 3.0 is a constant, so the error bar in the path length is the same as the error bar in the variable. HTH, B -- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 743, Room 114 Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/
Thank you!
Dimitar
On Fri, Oct 14, 2016 at 6:54 AM, Bruce Ravel
On 10/13/2016 05:17 PM, Dimitar Popmintchev wrote:
I would like to ask, after a fit (in Artemis) which column in the output file gives the uncertainty for peaks position dR (R+/-dR i.e. 3+/-0.02 Angstroms) ?
Error bars are not propagated in Artemis currently. That's something you, the user, has to do using the math expression that relates your variable(s) to the delta R in question.
The simplest common case is one where you have
guess delr = 0
then later, for some path,
reff = 3.0 deltaR = delr
In that case, delr is varied and the path length is 3.0 + delr.
Propagating the uncertainty in this case is trivial:
delta( 3.0 + delr) = delta(3.0) + delta(delr)
3.0 is a constant, so the error bar in the path length is the same as the error bar in the variable.
HTH, B
-- Bruce Ravel ------------------------------------ bravel@bnl.gov
National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 743, Room 114 Upton NY, 11973
Homepage: http://bruceravel.github.io/home/ Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/ _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
participants (2)
-
Bruce Ravel -
Dimitar Popmintchev