{
    // observables
    RooRealVar x("x", "random var x", 0.0, 1.0);
    RooRealVar y("y", "random var y", 0.0, 1.0);
    
    // Gaussian model of x
    RooRealVar mu("mu", "mean parameter", 0.5, 0.0, 1.0);
    RooRealVar sigma("sigma", "width parameter", 0.1, 0.0, 0.3);
    RooGaussian gaus("gaus", "Gaussian PDF", x, mu, sigma);
    
    // Polynomial of y: 1 + p1*y + p2*y^2
    RooRealVar p1("p1", "coeff. of y^1", +0.3, -10., 10.);
    RooRealVar p2("p2", "coeff. of y^2", -0.8, -10., 10.);
    RooPolynomial poly("poly", "2nd order poly.", y, RooArgSet(p1,p2));
    
    // product: Gaussian(x) * Polynomial(y)
    RooProdPdf model("model","PDF model", gaus,poly);
    
    TH1* model_hist = model.createHistogram("x,y",50,50);
    model_hist->Draw("surf");
}