vtxFit.cxx

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void vtxFit() {
 
  Double_t chik, kvx, kvy, kvz, ndofk, probk;
  TChain*  t = new TChain( "kalvtx" );
  t->Add( "run_0009903_dst_pvtx2.root" );
  t->Add( "run_0009903_dst_pvtx3.root" );
  t->SetBranchAddress( "chik", &chik );
  t->SetBranchAddress( "kvx", &kvx );
  t->SetBranchAddress( "kvy", &kvy );
  t->SetBranchAddress( "kvz", &kvz );
  t->SetBranchAddress( "ndofk", &ndofk );
  t->SetBranchAddress( "probk", &probk );
 
  Int_t nentries = (Int_t)t->GetEntries();
 
  TH1D* m_vertex_x_kal = new TH1D( "x of vertex in kal", "x of vertex in kal", 60, -0.6, 0.6 );
  TH1D* m_vertex_y_kal = new TH1D( "y of vertex in kal", "y of vertex in kal", 60, -0.6, 0.1 );
  TH1D* m_vertex_z_kal = new TH1D( "z of vertex in kal", "z of vertex in kal", 60, -6, 6 );
 
  for ( Int_t i = 0; i < nentries; i++ )
  {
    t->GetEntry( i );
    m_vertex_x_kal->Fill( kvx );
    m_vertex_y_kal->Fill( kvy );
    m_vertex_z_kal->Fill( kvz );
  }
 
  TCanvas* myC        = new TCanvas( "myC", "myC", 1200, 400 );
  TPad*    background = (TPad*)gPad;
  background->SetFillColor( 10 );
  myC->Divide( 3, 1 );
  myC->cd( 1 );
 
  TF1* func = new TF1( "func", "gaus", -0.6, 0.6 );
  m_vertex_x_kal->Fit( "func", "R+" );
  Double_t MeanXKal     = func->GetParameter( 1 );
  Double_t SigmaXKal    = func->GetParameter( 2 );
  Double_t ErrMeanXKal  = func->GetParError( 1 );
  Double_t ErrSigmaXKal = func->GetParError( 2 );
 
  myC->cd( 2 );
  TF1* funcY = new TF1( "funcY", "gaus", -0.6, 0.1 );
  m_vertex_y_kal->Fit( "funcY", "R+" );
  Double_t MeanYKal     = funcY->GetParameter( 1 );
  Double_t SigmaYKal    = funcY->GetParameter( 2 );
  Double_t ErrMeanYKal  = funcY->GetParError( 1 );
  Double_t ErrSigmaYKal = funcY->GetParError( 2 );
 
  myC->cd( 3 );
  TF1* funcZ = new TF1( "funcZ", "gaus", -6, 6 );
  m_vertex_z_kal->Fit( "funcZ", "R+" );
  Double_t MeanZKal     = funcZ->GetParameter( 1 );
  Double_t SigmaZKal    = funcZ->GetParameter( 2 );
  Double_t ErrMeanZKal  = funcZ->GetParError( 1 );
  Double_t ErrSigmaZKal = funcZ->GetParError( 2 );
 
  cout << "Kal: Mean X, Y, Z = " << MeanXKal << "  " << MeanYKal << "  " << MeanZKal << endl;
  cout << "Kal: Sigma X, Y, Z = " << SigmaXKal << "  " << SigmaYKal << "  " << SigmaZKal
       << endl;
 
  figs_name = "figs.ps";
  myC->SaveAs( figs_name );
 
  // ofstream file(file_name);
 
  cout << MeanXKal << " " << MeanYKal << " " << MeanZKal << " " << SigmaXKal << " "
       << SigmaYKal << " " << SigmaZKal << endl;
  cout << ErrMeanXKal << " " << ErrMeanYKal << " " << ErrMeanZKal << " " << ErrSigmaXKal << " "
       << ErrSigmaYKal << " " << ErrSigmaZKal << endl;
 
  return;
}