[ROOT] Mean value of the gaussian fit

From: ginn gin (ginng2001@yahoo.com)
Date: Fri Aug 29 2003 - 17:58:05 MEST


Hi,
   Thank you for the quick reply. I have changed it
and it works. Now I tried to do a gaussian fitting and
get the  Mean value for the fit. When I do it as shown
below, it gives me the Mean value of the histo before
the fitting. It does not give the Mean value of
fitting. How can I get this fixed? 

Thanks,

Ginn

I use RH 8.0 and ROOT 3.05
================= Program ===================
 {
     Double_t ave;
     Int_t i;
      
      TFile f("mpeak.root");
      TH1F *h2= new TH1F("h2","",50,0.,1000);
      gStyle->SetOptFit();  
     for( i=6480; i<6500; i++){   
ntuple->Draw("bpul>>h2",Form("btub==55611&&ctub==%d",i);
       h2->Fit("gaus","R","same",0.,1000);
      ave = h2->GetMean();
      cout<<" average : "<<ave<<endl;
       }
 }
--- Rene Brun <brun@pcbrun.cern.ch> wrote:
> Hi,
> 
> Replace the line:
>      
> ntuple->Draw("bpul>>h2","btub==55611&&ctub==i");
> by
>      
>
ntuple->Draw("bpul>>h2",Form("btub==55611&&ctub==%d",i));
> 
> Rene Brun
> 
> On Wed, 27 Aug 2003, 
> ginn gin wrote:
> 
> > Hi,
> >     I need to open a root file and look for
> histograms
> > and get the mean value of each histogram. One of
> the
> > cut is each time changing. I need to put this as i
> and
> >  initialize i in a for loop. Then i is the one of
> the
> > value in ntuple->Draw(.....). When I gave ctub ==
> 6480
> > without for loop it works. With the for loop i
> need to
> >  give values for i= 6480,6481 etc. If I run
> following
> > it complains about i. How can I get this fixed.
> Any
> > hint or help is appreciated.
> > 
> > Thank you, 
> > gin
> > =========Here is the program and what is wrong ===
> > 
> > {
> >     Double_t ave;
> >     Int_t i;
> >      
> >      TFile f("mpeak.root");
> >      TH1F *h2= new TH1F("h2","",50,0.,1000);
> > 
> >      for( i=6480; i<6500; i++){
> >     
> ntuple->Draw("bpul>>h2","btub==55611&&ctub==i");
> >      ave = h2->GetMean();
> >      cout<<" average : "<<ave<<endl;
> >       }
> > }
> > 
> > __________________________________
> > Do you Yahoo!?
> > Yahoo! SiteBuilder - Free, easy-to-use web site
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> > 
> 


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