void bigTGraph(){

  const long nPoints(2000000);

  TGraph *graph = new TGraph();
  TRandom3 rand(0);
  
  for (long i=0; i<nPoints; i++){

    graph->SetPoint(i,rand.Uniform(0,10),rand.Uniform(0,10));
    
  }

  TCanvas *canvas = new TCanvas();

  graph->Draw("AP");

  canvas->Print("bigTGraph.pdf");
}