[Ifeffit] Too many points in pre-edge

Carlo U. Segre segre at iit.edu
Thu Dec 2 14:15:55 CST 2004


Grant has been using a differential evolution algorithm to take case of 
noisy data.  Perhaps this could help?

Carlo


On Thu, 2 Dec 2004, Bruce Ravel wrote:

>
> I, too, would be interested in a perfectly robust against noise
> algorithm for finding the edge energy.  However, I suspect that when
> someone builds a better algorithm, somoeone else will build noisier
> data ;-)
>
> Athena does have a feature that might be some help in this case.  In
> the "bkg" section of the preferences, one of the parameters is "e0".
> This is set to "derivative" by default, telling Athena to use
> Ifeffit's first derivative based algorithm to determine e0.  Unless
> the noise in the pre-edge is really large, the "half" option for that
> parameter might be helpful.  It's described right there on the
> preferences page.
>
> Another things that might help is Athena's pre-processing of data as
> it's imported.  If all goes well, then you will have to set e0 by hand
> for the first data set, but choosing the "set all parameter values"
> option in the processing dialog should set all the rest to reasonable
> values.
>
> In any case, if you have noisy data, you really must be prepared to do
> hands-on data analysis.  Ifeffit and Athena will only ever be so
> smart, but data can be arbitrarily crappy!
>
> B
>
>

-- 
Carlo U. Segre -- Professor of Physics
Associate Dean for Special Projects, Graduate College
Illinois Institute of Technology
Voice: 312.567.3498            Fax: 312.567.3494
Carlo.Segre at iit.edu    http://www.iit.edu/~segre



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