#include "RooRealVar.h"
#include "RooGaussian.h"
#include "RooPolynomial.h"
#include "RooAddPdf.h"
#include "RooProdPdf.h"
#include "RooDataSet.h"
#include "RooPlot.h"
#include "RooLandau.h"
#include "TCanvas.h"
#include "RooNumIntConfig.h"
using namespace RooFit;
void script_error (){

  Int_t EventGen = 4000;

  // signal pdf  == gaussian
  RooRealVar x ("x","x",5.0,0.0,10.0);      RooRealVar m  ("m" ,"m",5.0,2.0,8.0);
  RooRealVar s ("s","s",1.0,0.1,10.1);      RooGaussian sig ("sig","sig",x,m,s);

  // bkgd pdf  ==  flat 
  RooRealVar slopex ("slopex","slopex",0.0);  RooPolynomial bkg1 ("bkg1","bkg1",x,RooArgList(slopex));
  RooRealVar slopes ("slopes","slopes",0.0);  RooPolynomial bkg2 ("bkg2","bkg2",s,RooArgList(slopes));
  RooProdPdf bkg ("bkg","bkg",RooArgList(bkg1,bkg2));

  // build pdf 
  RooRealVar frac  ("frac" ,"frac",0.1);    RooAddPdf pdf ("pdf","pdf",RooArgList(bkg,sig),RooArgList(frac));

  // generate sigma first, its pdf is a sharp landau peaked at 1
  RooRealVar landau_mode ("landau_mode","landau_mode",1);
  RooRealVar landau_sgma ("landau_sgma","landau_sgma",0.0001);
  RooLandau pdfS ("pdfS","pdfS",s,landau_mode,landau_sgma);
  RooDataSet *expS = pdfS.generate(s,EventGen);
  RooDataSet *data = pdf.generate(x,ProtoData(*expS));
  
  RooPlot *frame = s.frame(Bins(3),Range(0.94,1.06));     data->plotOn(frame);
 
  //  plot x and pdf
  RooPlot *frame2 = x.frame(Bins(10));
  data->plotOn(frame2,LineColor(kRed));  
  pdf.plotOn(frame2,ProjWData(s,*data));
  pdf.plotOn(frame2,Components(sig),ProjWData(s,*data));
  pdf.plotOn(frame2,Components(bkg),ProjWData(s,*data));
  TCanvas *c2 = new TCanvas ("c2","c2",1000,700);  c2->Divide(2);
  c2->cd(1);  frame->Draw();  c2->cd(2);  frame2->Draw();
  
}