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 > design software > > http://sitebuilder.yahoo.com > > > __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com
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