We detected an error in the way a TGraphAsymmErrors behaves during plot in three different versions of ROOT using the same script.
The only correct version appears to be ROOT V5.22/00d: the representation error is most evident at the baseline of the curve (where the content of each bin is supposed to be exactly zero). Curiously enough, the correct version is an intermediate version between two incorrect ones.
Here is the code:
[code]#include “TMath.h”
#include “iostream.h”
void BayesianErrors()
{
gROOT->Reset() ;
string title = string("TGraphAsymmErrors with ROOT version ") + gROOT->GetVersion() ;
TH1I * Total = new TH1I ( title.c_str(),title.c_str(), 17 , 0, 17 );
TH1I * Pass = new TH1I ( “Pass”, “Pass”, 17 , 0, 17 );
Total->SetBinContent( 1,10); Pass->SetBinContent( 1, 0);
Total->SetBinContent( 2,10); Pass->SetBinContent( 2, 0);
Total->SetBinContent( 3,10); Pass->SetBinContent( 3, 0);
Total->SetBinContent( 4,10); Pass->SetBinContent( 4, 1);
Total->SetBinContent( 5,10); Pass->SetBinContent( 5, 1);
Total->SetBinContent( 6,10); Pass->SetBinContent( 6, 1);
Total->SetBinContent( 7,10); Pass->SetBinContent( 7, 1);
Total->SetBinContent( 8,10); Pass->SetBinContent( 8, 2);
Total->SetBinContent( 9,10); Pass->SetBinContent( 9, 3);
Total->SetBinContent(10,10); Pass->SetBinContent(10, 7);
Total->SetBinContent(11,10); Pass->SetBinContent(11, 9);
Total->SetBinContent(12,10); Pass->SetBinContent(12, 9);
Total->SetBinContent(13,10); Pass->SetBinContent(13, 9);
Total->SetBinContent(14,10); Pass->SetBinContent(14,10);
Total->SetBinContent(15,10); Pass->SetBinContent(15,10);
Total->SetBinContent(16,10); Pass->SetBinContent(16,10);
Total->SetBinContent(17,10); Pass->SetBinContent(17,10);
TGraphAsymmErrors * tgraphasymmerrors = new TGraphAsymmErrors();
tgraphasymmerrors->BayesDivide(Pass,Total);
TCanvas* c1 = new TCanvas(“c1”,“Efficiency Curve”,50,50,600,600);
TH1F hFrame = ((TPad)c1->cd())->DrawFrame(0.,-.1,17.,1.1);
Total->Draw() ;
Total->SetMaximum(1.1) ;
Total->SetMinimum(-.1) ;
TLine upper(0.,1.,17.,1.) ; TLine lower(0.,0.,17.,0.) ;
upper.SetLineColor(2) ;
lower.SetLineColor(4) ;
upper.DrawLine(0.,1.,17.,1.) ;
lower.DrawLine(0.,0.,17.,0.) ;
tgraphasymmerrors->Draw(“SAMEP0”);
}
[/code]
