Mauro: In a paper we just submitted, we included a consise description of the model as a footnote to the table of fit parameters. This should be sufficient. Carlo On Mon, 2 May 2005, MauRo wrote:

Hi folks,

I would like to ask you if it exist one common convention, apart the XAFS society one, to report IFEFFIT results when you have unusual math expressions.

In particular, I have used a two-phase model (two FEFF calculations) to fit my sample and for the amplitude variable I have these math expressions:

amp_feff1 = amp * x amp_feff2 = amp * y = amp * (1-x)

In this way I can estimate the global amplitude variable and introduce a "percentage" of the two chemical compounds (correlation is kept under control).

How to explain what I have done to a non-ifeffiter?

Mauro

--- Mauro Rovezzi Physics student @ GILDA BM08 c/o ESRF (Grenoble, France)

_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit

-- 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

On Monday 02 May 2005 12:30, MauRo wrote:

I would like to ask you if it exist one common convention, apart the XAFS society one, to report IFEFFIT results when you have unusual math expressions.

In particular, I have used a two-phase model (two FEFF calculations) to fit my sample and for the amplitude variable I have these math expressions:

amp_feff1 = amp * x amp_feff2 = amp * y = amp * (1-x)

In this way I can estimate the global amplitude variable and introduce a "percentage" of the two chemical compounds (correlation is kept under control).

How to explain what I have done to a non-ifeffiter?

In this case, your parameter can be described by fairly common language. Here you are fitting your spectrum as a linear combination of the two phases and your parameter x is the "mixing parameter" or "weighting parameter" used to quantify the contributions of the phases. This is one of the things I like a lot about Ifeffit's very general way of parameterizing the fit. You are free to define parameters which have a direct physical interpretation and then hide the implementation details in your math expressions, which can then be as complicated as you need them to be. Often, it is outside the scope of a paper to provide all the ugly details and it suffices to just talk about these parameters and their direct physical interpretations. This might actually make it easier to discuss your exafs results with the non-ifeffiter or even the non-exafs person! B -- Bruce Ravel ----------------------------------- bravel@anl.gov -or- ravel@phys.washington.edu Environmental Research Division, Building 203, Room E-165 Argonne National Laboratory phone and voice mail: (1) 630 252 5033 Argonne IL 60439, USA fax: (1) 630 252 9793 My homepage: http://feff.phys.washington.edu/~ravel EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/