#include "RooRealVar.h"
 #include "RooDataSet.h"
 #include "RooGaussian.h"
 #include "RooConstVar.h"
 #include "RooChebychev.h"
 #include "RooAddPdf.h"
 #include "RooSimultaneous.h"
 #include "RooCategory.h"
 #include "TCanvas.h"
 #include "TAxis.h"
 #include "RooPlot.h"
 
 
  using namespace RooFit;
 
 void Simple_Fit()
 {
 
 		
 
    // Create observables
	RooRealVar MBC("MBC","Mbc [GeV/c^{2}]",5.23,5.29);

 
    
    // Construct signal pdf
    
  	//--- Signal mbc ---//
	RooRealVar Sig_mean("Sig_mean","#mu_Mbc", 5.279787, 5.25, 5.29);
	RooRealVar Sig_sigma("Sig_sigma","#sigma_Mbc", 0.003, 0.0, 1.0);
	RooGaussian Sig("Sig", "Signal", MBC, Sig_mean, Sig_sigma);



	/*
      	// Create a container to store data (dataset)
      	RooDataSet *data = new RooDataSet("data", "data", MBC);
  
	// Create tree (tchain) object for treename = extree      	
      	TChain *ch = new TChain("extree");
      	// Add root file
      	ch->Add("Root_Files/Signal_Mbc.root");
      	
      	// Save entries to dataset by looping over root file
      	int nent = ch->GetEntries();
      	for(int ii=0; ii<nent; ii++)
      	{
      		ch->GetEntry(ii);
      		double mbc = ch->GetLeaf("Mbc")->GetValue();
      		MBC.setVal(mbc);
      		
      		data->add(MBC);
      	}
	*/
      	
	// Generate a toy MC dataset
	RooDataSet* data = Sig.generate(MBC, 2000);
	
	// Perform extended ML fit to toy data:
	Sig.fitTo(*data);
	
	// Plot toy data and fit overlaid:
	RooPlot* xframe = MBC.frame();
	
	data->plotOn(xframe);
	Sig.plotOn(xframe);
	//Sig.paramOn(xframe);
	xframe->Draw();


	
}