Re: [ROOT] minimization class within ROOT

From: Sébastien Gadrat (gadrat@clermont.in2p3.fr)
Date: Tue Nov 30 2004 - 14:57:37 MET


Hi Rene, hi rooters,

I am trying to fit several spectra obtained with different set of cuts. 
Most of them can be fit easily with one or both minimizers (I usually 
use both as cross check), i.e. TMinuit and TFumili. But sometimes, the 
fit failed for both. This seem to be due to some little bit correleted 
parameters of my user defined functionnal. I could try to rewrite it but 
I put it in an easy way for later use. So I would like to keep it as it 
is and I was thinking about new minimizers... Especially, I heard some 
minimizers can overcome correlation within parameters (Lagrange 
multiplicators). So I wondered whether we have such minimizers in ROOT.
Thanks in advance,
Best regards,

Sebastien

Rene Brun wrote:
> Hi Sebastien,
> 
> Currently, we have only two classes of minimizers (The Minuit family
> and TFumili).
> We are currently working on a linear fitter that could be used
> to fit distributions with a combination of linear functions.
> Instead of a conventional minimisation, this implies only a matrix
> inversion.
> A RobustFitter algorithm is also in the pipeline.
> 
> Could you indicate the rationale behind your question?
> 
> Rene Brun



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