[ROOT] Entries of stat box is not valid ?

From: Harufumi Tsuchiya (harufumi@icrr.u-tokyo.ac.jp)
Date: Wed Jun 11 2003 - 11:24:59 MEST 

Hello ROOTers,

I found odd behevior of histogram with respect to stat box.

I attached sample macro with this e-mail(histtest.cpp).
After running the macro, please look entries of two histograms in stat box.
Two hisograms must have the same entries since one histogram is clone of
the other one, I think. 
But, the entries of the clone histogram is added only by number of bin.
(<entries of clone> = <entries of original> + <number of bin of histogram>).

Is this valid feature ?

I use ROOT v 3.05/05 (CVS update (May 9, 2003)) on IRIX65 with gcc 2.95.2.




void histtest() {
  const Int_t nbin = 30;
  Double_t Emin = 10, Emax = 100e3;
  Double_t lmin = TMath::Log10(Emin);
  Double_t lmax = TMath::Log10(Emax);
  Double_t diff = (lmax - lmin)/nbin;
  Double_t index, ebins[nbin+1];
  for ( Int_t i = 0; i <= nbin; i++ ) {
    index = lmin + diff*Double_t(i);
    ebins[i] = TMath::Power(10, index);
  }
  TCanvas *c = new TCanvas("c", "", 10, 10, 500, 700);
  c->Divide(1, 2);
  TH1F *h = new TH1F("h", "", nbin, ebins);
  Double_t E;
  for ( Int_t i = 0; i < 1000; i++ ) {
    index = lmin + (lmax-lmin)*(gRandom->Rndm(0));
    E = TMath::Power(10, index);
    cout << E << endl;
    h->Fill(E);
  }
  c->cd(1);
  h->Draw("ehist");
  gPad->SetLogx(); gPad->SetLogy();
  gPad->Modified();  gPad->Update();

  c->cd(2);
  TH1F *h2 = (TH1F*)h->Clone("h2");
  Double_t N, Nerr, dE;
  for ( Int_t i = 0; i <= nbin; i++ ) {
    N = h2->GetBinContent(i+1);
    Nerr = h2->GetBinError(i+1);
    dE = h2->GetBinWidth(i+1);
    N /= dE; Nerr /= dE;
    h2->SetBinContent(i+1, N); h2->SetBinError(i+1, Nerr);
  }
  h2->Draw("ehist");

  gPad->SetLogx(); gPad->SetLogy();
  gPad->Modified();  gPad->Update();
  
}

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