[ROOT] Error propagation in ProjectionX

From: William Love (love@bnl.gov)
Date: Wed Dec 04 2002 - 22:07:05 MET


  Roottalk

  I made a simpler version of my problem.  I forgot to mention
 that I am running Root  3.03/09 on Linux


#include "TH2.h";
#include "TH1.h";
TH2D *exam;
void Simple(){

  exam = new TH2D("exam","demo",36,-1.8,1.8,36,-180,180);
    for (int i=0;i<36;i++)
      {
      for (int j=0;j<36;j++)
 {
 exam->SetBinContent(i+1,j+1,100000);
      }
    }
  exam->Sumw2();
  cout << " bin 10,10 = " << exam->GetBinContent(10,10) <<" " <<
exam->GetBinError(10,10) <<endl;
  exam->ProjectionX("pro1",10,10,"e");
  cout << "projection " << pro1->GetBinContent(10) << " " <<
pro1->GetBinError(10) << endl;
  pro1->Draw();
  return();
}

  This code prints
 *** Start at Date : Wed Dec  4 16:07:41 2002
QAInfo:You are using STAR_LEVEL : dev, ROOT_LEVEL : 3.03.09 and node :
rcas6006.rcf.bnl.gov
root.exe [0]
Processing Simple.C...
 bin 10,10 = 100000 316.228
projection 100000 100000
<TCanvas::MakeDefCanvas>: created default TCanvas with name c1

   Bill Love
He was screaming in agony.  Fortunately I speak it fluently.



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