#include <TF1.h>
#include <TH1D.h>
#include <TStyle.h>
#include <TCanvas.h>
#include <TRatioPlot.h>


void ratioplot1() {
   gStyle->SetOptStat(0);
   auto c1 = new TCanvas("c1", "A ratio example");
   auto h1 = new TH1D("h1", "h1", 50, 0, 10);
   auto h2 = new TH1D("h2", "h2", 50, 0, 10);
   auto f1 = new TF1("f1", "exp(- x/[0] )");
   f1->SetParameter(0, 3);
   h1->FillRandom("f1", 1000);
   h2->FillRandom("f1", 1000);
   h1->Sumw2();
   h2->Scale(1.9 / 2.);
   h1->GetXaxis()->SetTitle("x");
   h1->GetYaxis()->SetTitle("y");
   
   TH1D *h3 = (TH1D*)h1->Clone("h3");
   h3->Scale(0.5);

   h1->Scale(1.e-10);
   h2->Scale(1.e-10);
   h3->Scale(1.e-10);
   
   auto rp = new TRatioPlot(h1, h2);
   rp->GetUpperPad()->SetBottomMargin(0);
   rp->GetLowerPad()->SetTopMargin(0);
   c1->SetTicks(0, 1);
   rp->Draw();

   rp->GetUpperPad()->cd();
   h3->Draw("Same");
   rp->GetLowerRefGraph()->SetMaximum(2.);
   rp->GetLowerRefGraph()->SetMinimum(0.);
   c1->Update();
   c1->Print("ratioPlotTest.eps");
   c1->Print("ratioPlotTest.pdf");
   c1->Print("ratioPlotTest.png");
}