#include <iostream>
#include <fstream>
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "TCanvas.h"
#include "RooPlot.h"
#include "TAxis.h"
using namespace RooFit ;


#include<RooFit.h>
void exe2()
{
// create model
TFile *f=new TFile("exe2.root","recreate");
   RooWorkspace *w=new RooWorkspace("w","");
   w->factory("x[110,160]");  // invariant mass
   
   // create exponential model as two components
   w->factory("a1[ 7.5, -500, 500]");
   w->factory("a2[-1.5, -500, 500]");
   w->factory("expr::z('-(a1*x/100 + a2*(x/100)^2)', a1, a2, x)");
   w->factory("Exponential::bkg_pdf(z, 1)");
    // signal model   
   w->factory("mass[130, 110, 150]");
   w->factory("width[1, 0.5, 5]");
   w->factory("Gaussian::sig_pdf(x, mass, width)");
//w->factory("Gaussian:pdf(x[-10,10],mu[1,-1000,1000],s[2,0,1000])");   
   // create RooAddPdf in extended mode
   w->factory("nbackground[1000,0,100000]");
   w->factory("nsignal[100, 0.0, 1000.0]");
   w->factory("SUM::model(nbackground*bkg_pdf, nsignal*sig_pdf)");
// w.factory("SUM:model(nsig[100,0,10000]*sig_pdf, nbkg[1000,0,10000]*bkg_pdf)");  // for extended model

 //read
RooRealVar *x=w->var("x");
RooAbsPdf *model=w->pdf("model");
RooPlot *plot=x->frame();
TTree *T=new TTree("tree","data from hig.txt");
T->ReadFile("hig.txt","x");//ATTENTION!!x should be consistent with RooRealVar
T->Draw("x");
double num=T->GetEntries();
RooDataSet data("data","",*x,Import(*T));
// fit the data and save its result. Use eventually the optional =Minuit2= minimiser
RooFitResult * res =model->fitTo(data,/* Minimizer("Minuit2","Migrad"),*/ Save(true) );
data.plotOn(plot);
//draw the two separate pdf's
RooAbsPdf *sig_pdf=w->pdf("sig_pdf");
RooAbsPdf *bkg_pdf=w->pdf("bkg_pdf");
RooAbsPdf *abs=w->pdf("model");
bkg_pdf->plotOn(plot);//, RooFit::Components("bkg_pdf"), RooFit::LineStyle(kDashed) );
//abs->plotOn(plot);
//sig_pdf->plotOn(plot);//,RooFit::Components("sig_pdf");
RooFit::LineColor(kRed);
RooFit::LineStyle(kDashed);
model->plotOn(plot);
plot->Draw();   // to show the RooPlot in the current ROOT Canvas
RooRealVar *nbkg=w->var("nbackground");
RooRealVar *nsig=w->var("nsignal");
cout<<"nbkg="<<nbkg->getVal()<<endl;
cout<<"nsig="<<nsig->getVal()<<endl;
cout<<num<<endl;
w->Print();

}