Re: [ROOT] fit with TGraph..

From: Rene Brun (Rene.Brun@cern.ch)
Date: Wed Jan 17 2001 - 22:28:36 MET


Hi Antoni,
This problem was fixed in 2.24/05 (26 May 2000).
Move to a more recent version.

Rene Brun

On Wed, 17 Jan 2001, Antoni Munar wrote:

> 
> 
> I am using ROOT version 2.24/04 on IRIX at CDF
> 
> When I fit a TGraph with a polinomial function of grade 1
> I have problems retreiving the fitting parameters.
> 
> I do the follow:
> 
>     TGraph *emGr[24];
>     TGraph *hadGr[24];
>     ..................
> 
>     for(k1=0.................
> 	
>     emGr[k1]= new TGraph(nentries,xetmp,yetmp);
>     hadGr[k1]= new TGraph(nentries,xhadtmp,yhadtmp);
>     //xetmp and yetmp are arrays
> 	
>     emGr[k1]->Fit("pol1","Q","");
>     hadGr[k1]->Fit("pol1","Q","");
> 
>     emf[k1] = emGr[k1]->GetFunction("pol1");
>     if(emf[k1]!=0) 
>       printf("p1: %f\n",emf[k1]->GetParameter(1));
> 
> my problem is that the pointer returned by GetFunction is always 0...
> 
> Any suggestion...
> 
> Thanks very much
> 
> **************************************************************
> *    Antoni Munar Ara        	   munar@fnal.gov            *
> *                                                            *
> *    INFN Sezione di Pisa                                    *
> *    Fermi National Laboratory     Phone:  (630)840-8426     *
> *    P.O. Box 500, MS 223                                    *
> *    Batavia, IL 60510                                       *
> *    U.S.A.                                                  *
> **************************************************************
> 



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