using namespace RooFit;

void korrelationen()
{
  gStyle->SetPalette(1);
  RooWorkspace work("work",kTRUE) ;
  work.factory("expr::func('a0*(x-a1)*(x-a1)+a2',x[-5,5],a0[-0.2],a1[0],a2[3])");
  work.factory("Gaussian::g(y[-5,5],func,sigma[0.5])");

  // RooPlot* frame = work::g.frame();
  // work::func.plotOn( frame );
  // frame->Draw();

  TH2* h = work::g.createHistogram("x,y"); //data->createHistogram("x,y");
  //  h->Draw("cont3");
  h->SetStats( 0 );
  h->SetTitle( "Unkorreliert, aber nicht unabhaengig!" );
  h->Draw();

  cout << h->GetCorrelationFactor() << endl;
  gPad->SaveAs( "uncorr_not_indep.pdf" );

  // multivariater Gauss
  // TMatrixDSym cov(2) ; 
  // cov(0,0) = cov(1,1) = 1 ; 
  // cov(1,0) = cov(0,1) = -0.3;

  // TVectorD s(2);
  // mu(0) = mu(1) = 0;

  // RooArgList xvec, muvec;

  // RooRealVar* x = new RooRealVar( "x", "x", 0, -5, 5 );
  // xvec.add( *x );
  // RooRealVar* y = new RooRealVar( "y", "y", 0, -5, 5 );
  // xvec.add( *y );

  // RooRealVar* mu1 = new RooRealVar( "mu1","mu1", 0);
  // muvec.add( *mu1 );
  // RooRealVar* mu2 = new RooRealVar( "mu2","mu2", 0);
  // muvec.add( *mu2 );

  // RooMultiVarGaussian mvg( "mvg", "mvg", xvec, muvec, cov );
  // RooDataSet* data = mvg.generate( xvec, 500 );
  
  // TH2* h = data->createHistogram("x,y");
  // h->SetStats( 0 );
  // h->SetMarkerStyle( 2 );
  // // h->SetTitle( "Positive Korrelation" );
  // h->SetTitle( "Negative Korrelation" );
  // h->Draw();

  // cout << h->GetCorrelationFactor() << endl;
  // //gPad->SaveAs( "positive_corr.pdf" );
  // gPad->SaveAs( "negative_corr.pdf" );

  // work.import(m,"cov");
  // work.import(s,"sig");
  
  // work.factory("MultiVarGaussian::mvg({x[-5,5],y[-5,5]},sig,cov)");
  
  // TH2* h = work::mvg.createHistogram("x,y");
  // h->SetStats( 0 );
  // h->SetTitle( "Zweidimensionale Gaussverteilung" );
  // h->Draw("cont3");

}