#ifndef __CINT__
#include "RooGlobalFunc.h"
#endif
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "TCanvas.h"
#include "RooPlot.h"
#include "TAxis.h"
using namespace RooFit ;


void TestLinear()
{
  RooRealVar x("x","x",-1,1) ;
  RooRealVar c0("c0","c0",50,-100,100) ;
  RooRealVar c1("c1","c1",10,-100,100) ;
  RooRealVar c2("c2","c2", 2,-100,100) ;

  RooGenericPdf BkgAngle1("BkgAngle1","c0+c1*x+c2*x*x",RooArgSet(x,c0,c1,c2));

  RooPlot* xframe = x.frame(Title("Linear p.d.f.")) ;
  c0.setVal(50) ;
  c1.setVal(10) ;
  c2.setVal(5) ;
  BkgAngle1.plotOn(xframe,LineColor(kRed)) ;
  c0.setConstant(false) ;
  c1.setConstant(false) ;
  c2.setConstant(false) ;

  RooDataSet* data = BkgAngle1.generate(x,10000) ;  
  
  RooPlot* xframe2 = x.frame(Title("Liear p.d.f. with data")) ;
  data->plotOn(xframe2) ;
  BkgAngle1.plotOn(xframe2) ;
  

  RooRealVar a0("a0","a0",50,-100,100) ;
  RooRealVar a1("a1","a1",10,-100,100) ;
  RooRealVar a2("a2","a2", 2,-100,100) ;
  RooGenericPdf BkgAngle2("BkgAngle2","a0+a1*x",RooArgSet(x,a0,a1));
  a0.setVal(0) ;
  a1.setVal(10) ;
  a2.setVal(2) ;
  BkgAngle2.plotOn(xframe,LineColor(kBlue)) ;
  a0.setConstant(false) ;
  a1.setConstant(false) ;
  a2.setConstant(false) ;

  BkgAngle2.fitTo(*data) ;

  a0.Print() ;
  a1.Print() ;
  a2.Print() ;

  TCanvas* c = new TCanvas("Basics","Basics",800,400) ;
  c->Divide(2) ;
  c->cd(1) ; gPad->SetLeftMargin(0.15) ; xframe->GetYaxis()->SetTitleOffset(1.6) ; xframe->Draw() ;
  c->cd(2) ; gPad->SetLeftMargin(0.15) ; xframe2->GetYaxis()->SetTitleOffset(1.6) ; xframe2->Draw() ;
}