#include <RooWorkspace.h>
#include <RooRealVar.h>
#include <RooAbsPdf.h>
#include <RooDataSet.h>
#include <RooPlot.h>

#include <TCanvas.h>
#include <TPad.h>
#include <TAxis.h>
#include <TH1.h>

void multiDimensional () {
  RooWorkspace w("w", kTRUE);

  // Construct F(x|y) -- a Gaussian in x with a mean that depends on y
  w.factory("PolyVar::meanX(y[-5, 5], {a0[-0.5, -5, 5], a1[-0.5, -1, 1]})");
  w.factory("Gaussian::gaussX(x[-5, 5], meanX, sigmaX[0.5])");

  // Construct G(y) -- an Exponential in y
  w.factory("Exponential::gaussY(y, -0.2)");

  // Construct M(x,y) = F(x|y)*G(y)
  w.factory("PROD::model(gaussX|meanX, gaussY)");

  RooDataSet *data = w.pdf("model")->generate(RooArgSet(*w.var("x"), *w.var("y")), 10000);
  w.pdf("model")->fitTo(*data);

  RooPlot *frame = w.var("x")->frame();
  data->plotOn(frame);
  w.pdf("model")->plotOn(frame);

  // Draw all frames on a canvas
  TCanvas *c = new TCanvas("multi-dimensional", "multi-dimensional", 800, 400);
  c->Divide(2);
  c->cd(1);
  gPad->SetLeftMargin(0.20);
  TH1 *hh_pdf = w.pdf("model")->createHistogram("x,y", *w.var("x"), RooFit::Binning(50),
                                                RooFit::YVar(*w.var("y"), RooFit::Binning(50)));
  hh_pdf->SetStats(kFALSE);
  hh_pdf->GetXaxis()->SetTitleOffset(1.5);
  hh_pdf->GetYaxis()->SetTitleOffset(1.6);
  hh_pdf->GetZaxis()->SetTitleOffset(2.5);
  hh_pdf->Draw("SURF");
  c->cd(2);
  gPad->SetLeftMargin(0.15);
  frame->GetYaxis()->SetTitleOffset(1.6);
  frame->Draw();
} // multiDimensional