{
  gROOT->SetStyle("Plain");

  RooRealVar x("x", "x", -10, 10);

  RooRealVar mu1("mu1", "average 1", 0, -1, 1);
  RooRealVar sigma1("sigma1", "sigma 1", 1, 0, 5);
  RooGaussian gauss1("gauss1","gaussian 1 PDF", x, mu1, sigma1);

  RooRealVar mu2("mu2", "average 2", 0.5, -1, 1);
  RooRealVar sigma2("sigma2", "sigma 2", 0.5, 0, 5);
  RooGaussian gauss2("gauss2","gaussian 2 PDF", x, mu2, sigma2);

  RooRealVar mu3("mu3", "average 2", -0.5, -1, 1);
  RooRealVar sigma3("sigma3", "sigma 2", 1.5, 0, 5);
  RooGaussian gauss3("gauss3","gaussian 2 PDF", x, mu3, sigma3);

  RooPlot * xFrame = x.frame();
  gauss1.plotOn(xFrame, RooFit::LineColor(kRed)) ;
  gauss2.plotOn(xFrame, RooFit::LineColor(kBlue)) ;
  gauss3.plotOn(xFrame, RooFit::LineColor(kMagenta)) ;
  TCanvas c;
  xFrame->Draw();
  c.SaveAs("01-gaussians.pdf");
}