void piechart()
{
   // Pie chart example.
   //Authors: Olivier Couet, Guido Volpi
   
   Float_t vals[] = {.2,1.1,.6,.9,2.3};
   Int_t colors[] = {2,3,4,5,6};
   Int_t nvals = sizeof(vals)/sizeof(vals[0]);

   TCanvas *cpie = new TCanvas("cpie","TPie test",700,700);
   cpie->Divide(2,2);

   TPie *pie1 = new TPie("pie1",
      "Pie with offset and no colors",nvals,vals);
   TPie *pie2 = new TPie("pie2",
      "Pie with radial labels",nvals,vals,colors);
   TPie *pie3 = new TPie("pie3",
      "Pie with tangential labels",nvals,vals,colors);
   TPie *pie4 = new TPie("pie4",
      "Pie with verbose labels",nvals,vals,colors);

   cpie->cd(1);
   pie1->SetAngularOffset(30.);
   pie1->SetEntryRadiusOffset( 4, 0.1);
   pie1->SetRadius(.35);
   pie1->Draw("3d");

   cpie->cd(2);
   pie2->SetEntryRadiusOffset(2,.05);
   pie2->SetEntryLineColor(2,2);
   pie2->SetEntryLineWidth(2,5);
   pie2->SetEntryLineStyle(2,2);
   pie2->SetEntryFillStyle(1,3030);
   pie2->SetCircle(.5,.45,.3);
   pie2->Draw("rsc");

   cpie->cd(3);
   pie3->SetY(.32);
   pie3->GetSlice(0)->SetValue(.8);
   pie3->GetSlice(1)->SetFillStyle(3031);
   pie3->SetLabelsOffset(-.1);
   pie3->Draw("3d t nol");
   TLegend *pieleg = pie3->MakeLegend();
   pieleg->SetY1(.56); pieleg->SetY2(.86);

   cpie->cd(4);
   pie4->SetRadius(.2);
   pie4->SetLabelsOffset(.01);
   pie4->SetLabelFormat("#splitline{%val (%perc)}{%txt}");
   pie4->Draw("nol <");
}