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@iit.edu http://www.iit.edu/~segre