[Ifeffit] Reporting math expressions in scientific papers

[Matt Newville]

Hi Mauro,

> 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).

I think it would be pretty clear if you just stated that the
relative concentrations of two phases were varid in the fit, but
with the constraint that the total concentration sum to 1.

The modeling can be more complicated than that ;).  It's usually
best if you can vary physical parameters (such as relative
concentrations, Debye Temperature, cluster size,....) which are
simple to interpret and explain.

--Matt