Re: [ROOT] How to use SIMPLEX

From: Rene Brun (Rene.Brun@cern.ch)
Date: Sun Jan 13 2002 - 09:35:10 MET


Hi Bertalan,

All what you describe is automatic when calling MIGRAD.

Rene Brun

On Sat, 12 Jan 2002, [iso-8859-1] Juhász Bertalan wrote:

> Hi Rene,
> 
> > The option to call "SIMPLEX" could be easily added. I am just curious
> > to know why you want to use SIMPLEX instead of MIGRAD (MIGRAD calls
> > SIMPLEX internally).
> 
> I want to use SIMPLEX because my professor wants me to do so... (That's
> quite a strong argument, isn't it?) According to him, SIMPLEX can find a
> minimum more easily than MIGRAD if the initial parameters are very much off.
> He wants to obtain a first guess of the parameters with SIMPLEX and then
> feed these parameter values to MIGRAD. But if you are right then we really
> do not need to start with SIMPLEX.
> 
> Cheers,
> 
> Bertalan
> 
> 
> >
> > Note that you can call directly the Minuit function mnsimp
> > via gMinuit->mnsimp(). You can see examples of direct calls to Minuit
> > or the TFitter in $ROOTSYS/tutorials/Ifit.C
> >
> > Rene Brun
> >
> > Bertalan Juhasz wrote:
> > >
> > > Dear Rooters,
> > >
> > > I would like to fit histograms starting with the SIMPLEX method instead
> of
> > > the default MIGRAD (which if called by TH1::Fit()). Is there a way to do
> > > this? A SIMPLEX function is persent in TMinuit but I couldn't figure out
> > > how to access and use it.
> > >
> > > Thanks in advance,
> > >
> > > Cheers,
> > >
> > > Bertalan
> >
> 
> 



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