doc/v606/rf703__effpdfprod_8C.html

#ifndef __CINT__

#include "RooGlobalFunc.h"

#endif

#include "RooRealVar.h"

#include "RooDataSet.h"

#include "RooGaussian.h"

#include "RooConstVar.h"

#include "RooExponential.h"

#include "RooEffProd.h"

#include "RooFormulaVar.h"

#include "TCanvas.h"

#include "TAxis.h"

#include "RooPlot.h"

using namespace RooFit ;


void rf703_effpdfprod()

{

  // D e f i n e   o b s e r v a b l e s   a n d   d e c a y   p d f

  // ---------------------------------------------------------------


  // Declare observables

  RooRealVar t("t","t",0,5) ;


  // Make pdf

  RooRealVar tau("tau","tau",-1.54,-4,-0.1) ;

  RooExponential model("model","model",t,tau) ;


  // D e f i n e   e f f i c i e n c y   f u n c t i o n

  // ---------------------------------------------------


  // Use error function to simulate turn-on slope

  RooFormulaVar eff("eff","0.5*(TMath::Erf((t-1)/0.5)+1)",t) ;


  // D e f i n e   d e c a y   p d f   w i t h   e f f i c i e n c y

  // ---------------------------------------------------------------


  // Multiply pdf(t) with efficiency in t

  RooEffProd modelEff("modelEff","model with efficiency",model,eff) ;


  // P l o t   e f f i c i e n c y ,   p d f

  // ----------------------------------------


  RooPlot* frame1 = t.frame(Title("Efficiency")) ;

  eff.plotOn(frame1,LineColor(kRed)) ;


  RooPlot* frame2 = t.frame(Title("Pdf with and without efficiency")) ;


  model.plotOn(frame2,LineStyle(kDashed)) ;

  modelEff.plotOn(frame2) ;


  // G e n e r a t e   t o y   d a t a ,   f i t   m o d e l E f f   t o   d a t a

  // ------------------------------------------------------------------------------


  // Generate events. If the input pdf has an internal generator, the internal generator

  // is used and an accept/reject sampling on the efficiency is applied.

  RooDataSet* data = modelEff.generate(t,10000) ;


  // Fit pdf. The normalization integral is calculated numerically.

  modelEff.fitTo(*data) ;


  // Plot generated data and overlay fitted pdf

  RooPlot* frame3 = t.frame(Title("Fitted pdf with efficiency")) ;

  data->plotOn(frame3) ;

  modelEff.plotOn(frame3) ;


  TCanvas* c = new TCanvas("rf703_effpdfprod","rf703_effpdfprod",1200,400) ;

  c->Divide(3) ;

  c->cd(1) ; gPad->SetLeftMargin(0.15) ; frame1->GetYaxis()->SetTitleOffset(1.4) ; frame1->Draw() ;

  c->cd(2) ; gPad->SetLeftMargin(0.15) ; frame2->GetYaxis()->SetTitleOffset(1.6) ; frame2->Draw() ;

  c->cd(3) ; gPad->SetLeftMargin(0.15) ; frame3->GetYaxis()->SetTitleOffset(1.6) ; frame3->Draw() ;


}