{
    vector<double> vec, prob1, prob2;
    double sigma;
    while(sigma<4.5) {
        vec.push_back(sigma);
        prob1.push_back(1.-TMath::Prob(sigma*sigma,1));
        prob2.push_back(1.-TMath::Prob(sigma*sigma,2));
        sigma += 0.05;
    }
    
    TCanvas *c1 = new TCanvas();
    c1->SetGrid();
    TGraph *g1 = new TGraph(vec.size(),vec.data(),prob1.data());
    g1->SetLineWidth(2);
    g1->GetXaxis()->SetTitleSize(0.05);
    g1->GetYaxis()->SetTitleSize(0.05);
    g1->GetXaxis()->SetTitle("n (#sigma)");
    g1->GetYaxis()->SetTitle("Probability");
    g1->Draw();
    TGraph *g2 = new TGraph(vec.size(),vec.data(),prob2.data());
    g2->SetLineWidth(2);
    g2->SetLineColor(kRed);
    g2->Draw("same");

    TLegend *leg1 = new TLegend(0.55,0.2,0.88,0.33);
    leg1->AddEntry(g1,"g1 p(n) in 1D","L");
    leg1->AddEntry(g2,"g2 p(n) in 2D","L");
    leg1->Draw();
}