void landau() 
{
  const double MAX = 10;
  TF1* flandau = new TF1( "flandau", "TMath::Landau(x,2,1,0)", 0, MAX );
  TH1* h2 = new TH1F( "hlandau", "Truncated Landau PDF", 1000, 0, MAX );

  const int N = 1000000;
  double x[ N ];
  for( int i = 0; i < N ; ++i ) {
    double rnd = gRandom->Landau( 2, 1 );
    if( rnd > MAX ) continue;
    x[i] = rnd;
    h2->Fill( rnd );
  }
  h2->Scale( 100./N );
  h2->SetMinimum( 0 );
  h2->SetMaximum( 0.2 );
  h2->Draw();
  flandau->Draw( "same" );
  
  TLine* l = new TLine();
  double median = TMath::Median( N, x );
  double mean   = h2->GetMean();
  double mode   = flandau->GetMaximumX();
  
  l->DrawLine( median, 0, median, 0.2 );
  l->DrawLine( mean, 0, mean, 0.2 );
  l->DrawLine( mode, 0, mode, 0.2 );

  gPad->SaveAs( "landau.pdf" );
}