Re: Get fit parameters from a TGraph

Hello Julia,

Your fitting fuction is not "n". "n" is your TGraph. What you need is here:

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

see section, "Access to the Fit results" and "Associated functions". What you are trying to do is described in "Associated functions".

John

Campa Romero, Julia Monica wrote:
>
> Hi,
>
> I want to access to the fit parameters once a TGraph is fitted with a
> gaussian. I am using GetFunction but it doesn't work. Bellow is my
> program. It displays the fit parameters but then if I use GetFunction
> as in the program bellow, it breaks when it gets the parameters. Could
> you help me to find the errors. A piece of the program is bellow:
>
> *******************
>
> TGraph *n= new TGraph(8,sig,l);
> n->Fit("gaus","V");
> TF1 *myfunc=n->GetFunction("n");
>
> Double_t p0=myfunc->GetParameter(0);
> Double_t p1=myfunc->GetParameter(1);
> Double_t p2=myfunc->GetParameter(2);
> **********************
> Cheers,
>
>
> Julia
>
>
>
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Received on Tue Sep 28 2010 - 17:11:48 CEST