#include "TGaxis.h"
plot_resolution(){
 
  gROOT->SetStyle("Plain");
  TCanvas * can = new TCanvas("can_resolution", "can_resolution", 600, 400);
  can->SetGridy();
  TF1 * f = new TF1("f", "sqrt(1/x+0.08*0.08)", 2, 50);
  f->SetNpx(10000);
  TH1D * h = f->GetHistogram();
  h->Draw();
  can->Update();
  float min_1 = gPad->GetUymin();
  float max_1 = gPad->GetUymax();

  cout << gPad->GetUymin() << endl;
  cout << gPad->GetUymax() << endl;

  TF1 * fSigma = new TF1("fSigma", "x*sqrt(1/x+0.08*0.08)", 2, 50);
  fSigma->SetNpx(10000);
  //fSigma->Draw();
  cout << endl;
  cout << gPad->GetUymin() << endl;
  cout << gPad->GetUymax() << endl;

  TH1D *hSigma = fSigma->GetHistogram();
  float min_2 = gPad->GetUymin();
  float max_2 = gPad->GetUymax();
  float scale = (max_1-min_1)/(max_2-min_2);
  hSigma->SetLineColor(kRed);
  //cout << "scale: "<< scale << endl;
  cout << endl;
  cout << gPad->GetUymin() << endl;
  cout << gPad->GetUymax() << endl;

  hSigma->Scale(scale);
  hSigma->Draw("same");
  TGaxis *axis = new TGaxis(gPad->GetUxmax(), min_1, gPad->GetUxmax(), max_1, min_2, max_2 , 510, "+L");
  axis->SetLineColor(kRed);
  axis->SetLabelColor(kRed);
  axis->Draw();
}