[SciPy-user] non linear optimisation

Christian K ckkart@hoc....
Mon Jun 11 21:07:59 CDT 2007


Ramon Crehuet wrote:
> Dear all,
>     I have a problem of non-linear optimisation (see below for a 
> experimental description). I have many experimental curves (x,y) and 
> want to fit the points to a non-linear function y=f(x; a,b,c...), where 
> a,b,c... are the parameters. I know how to do that. But the tricky thing 
> is that some parameters should be the same for all the curves, and some 
> are different for each curve, and I don't know if there is any module 
> that can help me in doing this non-linear fit of *all* the curves at the 
> same time.
>     For the experimental scientists, I will say that these curves 
> correspond to absorption spectra for the same compound in different 
> solvents. The model curve f(x; a,b,c...) has some parameters that depend 
> on the solvent and others that depend only on the compound, and thus, 
> should be the same for all the spectra.

Isn't it sufficient to determine the parameters corresponding to the absorption
peak that is apparent in all spectra once and then hold those parameters fixed
when ftting the other ones? Generally I would reccomend peak-o-mat
(http://lorentz/sf/net) for peak fitting.  It allows to define parameters as
fixed though it cannot fit many spectra at once like you want to do.

Christian



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