Re: [ROOT] Fitting in TGraphError

From: Rene Brun (Rene.Brun@cern.ch)
Date: Thu May 06 2004 - 15:09:49 MEST


Hi Alberto,

see the documentation of TGraph and TGraph::Fit, etc at:

http://root.cern.ch/root/htmldoc/TGraph.html
http://root.cern.ch/root/htmldoc/TGraph.html#TGraph:Fit
http://root.cern.ch/root/htmldoc/TGraph.html#TGraph:LeastSquareLinearFit

Rene Brun

Alberto Pulvirenti wrote:
> 
> Sorry, I forgot to put a topic in the email, and maybe many of you could
> have deleted it as spam.
> Here it is again.
> 
> Cheers,
>         Alberto
> 
> On Wed, 2004-05-05 at 15:38, Alberto Pulvirenti wrote:
> > Dear ROOTers,
> >
> > I have seen that it is possible to fit a TGraphErrors object with a
> > given TF1.
> >
> > My question is: does this fit take into account the errors which I pass
> > to this object, or not?
> > Maybe, must I specify something in order to accomplish this task?
> >
> > Another question: I saw in the class definition a method called
> >
> > virtual void LeastSquareLinearFit(Int_t n, Double_t& a0, Double_t& a1,
> > Int_t& ifail, Int_t first, Int_t last)
> >
> > Does it fit (according to parameters names) to which of the following?
> > 1) a0 + a1*x
> > 2) a0*x + a1
> >
> > What does 'ifail' mean?
> >
> > Thanks for all.



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