#include<iostream>
#include<TH1D.h>
#include<TF1.h>
#include<TCanvas.h>
#include<TRandom.h>
#include<TStyle.h>
#include<TLegend.h>
#include<TROOT.h>
#include<TPaveText.h>

void Esercizio1()
{

  //create empty histogram
  TH1D * h = new TH1D("histo", "", 40,0,40);
  //disable display of histogram statistics
  h->SetStats(false);
  //fill with Landau distribution
  for(double i = 0; i < 10000; i++) 
    h->Fill(gRandom->Landau(20,5));
  //fill with Gaus distribution
  for(double i = 0; i < 5000; i++) 
    h->Fill(gRandom->Gaus(5,3));
  
  //define fit functions
  TF1 * FitFunc1 = new TF1("FitFunc1","[0]*TMath::Gaus(x,[1],[2])",0,40);
  TF1 * FitFunc2 = new TF1("FitFunc2","[0]*TMath::Landau(x,[1],[2])",0,40);
  TF1 * FitFuncCombined = new TF1("FitFunc2","[0]*TMath::Gaus(x,[1],[2])+[3]*TMath::Landau(x,[4],[5])",0,40);
  //fit both peaks individually with reasonable initial parameters and fitting range
  FitFunc1->SetParameters(1,3,4);
  h->Fit(FitFunc1,"0","",0,10);
  FitFunc2->SetParameters(1,17,7);
  h->Fit(FitFunc2,"0","",10,40);
  
  //use fit parameters as initial parameters for combined fit
  FitFuncCombined->SetParameters(FitFunc1->GetParameter(0), FitFunc1->GetParameter(1), FitFunc1->GetParameter(2), FitFunc2->GetParameter(0), FitFunc2->GetParameter(1), FitFunc2->GetParameter(2));
  h->Fit(FitFuncCombined,"0","");

  //display what we did
  TCanvas * c = new TCanvas("c ref","c title", 200,10,600,600);
  c->SetLeftMargin(0.15);
  c->SetRightMargin(0.04);
  c->SetTopMargin(0.04);
  
  //Legend
  TLegend* Leg = new TLegend(0.3,0.8,0.99,0.99);
  Leg->SetFillColor(0);
  Leg->SetTextFont(62);
  h->SetLineWidth(2);
  h->SetLineColor(kBlue);
  h->GetXaxis()->SetTitle("x-axis title");
  h->GetYaxis()->SetTitleOffset(1.4);
  h->GetYaxis()->SetTitle("entries");
  h->Draw();
  
  TString text;
  text = Form("N=%5.0f Mean=%5.1f RMS=%5.1f", h->GetEntries(), h->GetMean(), h->GetRMS());
  Leg->AddEntry(h,text,"l");
  FitFunc1->SetLineStyle(2);
  FitFunc1->SetLineColor(kRed);
  FitFunc1->Draw("same");
  
  text = Form("Gaus: Mean=%5.1f#pm%5.1f, #sigma=%5.1f#pm%5.1f Landau: MOP=%5.1f#pm%5.1f, #sigma=%5.1f#pm%5.1f", 
	      FitFuncCombined->GetParameter(1), FitFuncCombined->GetParError(1), 
	      FitFuncCombined->GetParameter(2), FitFuncCombined->GetParError(2), 
	      FitFuncCombined->GetParameter(4), FitFuncCombined->GetParError(4), 
	      FitFuncCombined->GetParameter(5), FitFuncCombined->GetParError(5));
  
  Leg->AddEntry(FitFuncCombined,text,"l");
  FitFunc2->SetLineStyle(2);
  FitFunc2->SetLineColor(kRed);
  FitFunc2->Draw("same");
  FitFuncCombined->SetLineColor(kRed);
  FitFuncCombined->Draw("same");
  Leg->Draw();
  
  //Save canvas
  c->SaveAs("ex1.eps");
  c->SaveAs("ex1.png");
  c->SaveAs("ex1.root");
}