Dmitry Onoprienko wrote: > > When I use TTree::Project() function to fill a TH2F histogram, some data > members > (fTsumwy, fTsumwy2, fTsumwxy) are not calculated. As a result, some public > functions (GetRMS(), GetCorrelationFactor(), ...) produce incorrect results. > Using Draw() instead of Project() allows to avoid the problem. > > I'm running ROOT under Windows. Here is a test macro : > > { > #include <iostream.h> > > c1 = new TCanvas("c1","Ntuple projection test",500,500); > > TFile *f = new TFile("test.root", "RECREATE"); > > TNtuple *nt = new TNtuple("nt","test","x:y"); > TH2F *h = new TH2F("h","htitle",100,-4.,4.,100,-4.,4.); > > Float_t x,y; > Int_t event = 500; > TRandom rn = new TRandom(); > while (event-->0) { > nt->Fill(rn.Gaus(),rn.Gaus()); > } > f->Write(); > > nt->Project("h","x:y"); > h->Draw(); > c1->Update(); > cerr << "Now check statistics for the displayed histogram\n"; > cerr << "Mean and RMS along Y are zero, also\n"; > cerr << "h->GetCorrelationFactor() gives " << h->GetCorrelationFactor() > <<endl; > > } Hi Dmitry, Statistics for 2-d histograms were not filled by TTree::Draw. I have fixed this problem in version 2.21/04 Thanks for reporting this problem. Rene Brun
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