[ROOT] TGraph: bug in drawing smooth line

From: Miroslav Helbich (helbich@mail.desy.de)
Date: Fri Sep 14 2001 - 16:10:44 MEST


 Hi all,

 I have discovered the following bug. When I draw the TGraph object with
graph->Draw("AC") and restrict the histogram scale to ommit some points,
the line is not drawn through those points and treats them as if they
wouldn't exist. This is very dangerous and can fool many people: where is
the bump? This feature is not present in other options e.g 
graph->Draw("AL").

 I'm using  SuSE Linux 6.3 (i386) - Kernel 2.2.16 (pts/12)
 and root Version   3.01/05.

					Miro

To illustrate the problem

{
//=========Macro generated from canvas: c1/c1
//=========  (Tue Sep 11 14:48:02 2001) by ROOT version3.01/05
   TCanvas *c1 = new TCanvas("c1", "c1",10,10,700,500);
   c1->Range(-0.138363,-0.122176,1.23736,1.13146);
   c1->SetFillColor(0);
   c1->SetBorderMode(0);
   c1->SetBorderSize(2);
   c1->SetFrameFillColor(0);
   c1->SetFrameBorderMode(0);
   
   TGraph *graph = new TGraph(5);

   graph->SetPoint(0,0.1,0.5);
   graph->SetPoint(1,0.3,0.5);
   graph->SetPoint(2,0.5,0.5);
   graph->SetPoint(3,0.7,1.5);
   graph->SetPoint(4,1.,0.5);
   
   TH1 *Graph1 = new TH1F("Graph1","Pdf's enhancing high x
region",5,0.,1.);
   Graph1->SetMinimum(0);
   Graph1->SetMaximum(1.0); //note that 1.0 is less than highest point=1.5
   graph->SetHistogram(Graph1);
   
graph->DrawClone("AC"); // why the point n.4 is not connected?


}



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