Hi Roberta,
This was a possible difference looking at your code, maybe check also the range of the function in both cases. I can have a look at it, but I am right now in vacation and I could look at it only when I am back in the office in about 10 days. You should send me also the root file with the histograms data so I can run your code,
Cheers, Lorenzo
On Jul 27, 2011, at 5:52 PM, Roberta Arnaldi wrote:
> Hi Lorenzo,
>
> thanks a lot for the very fast answer!
> However, even if I remove from ROOT the option "I", I get even higher values wrt ROOFIT.
>
> - ROOT without "I" : CB integral: 2226 +- 189, CB width: 78 MeV
> - ROOT with "I": CB integral: 2220 +- 183, CB width: 76 MeV
> - ROOFIT: CB integral: 2090 +- 158, CB width: 72 MeV
>
> So this does not seem to explain the difference...
>
> Thanks,
>
> Roberta
>
>
> Lorenzo Moneta wrote:
>> Hi Roberta,
>> You are using in ROOT the option "I", integral of function in the bin. I don't think this is supported in RooFit and I guess this makes a difference in your case
>> Best Regards
>>
>> Lorenzo
>> On Jul 27, 2011, at 5:28 PM, Roberta Arnaldi wrote:
>>
>>
>>> Dear All,
>>>
>>> I'm fitting an invariant mass spectrum histogram with a sum of functions (Crystal Ball for the peak and two exponentials for the background), using ROOT or ROOTFIT.
>>> Initial parameters, fit limits...are the same in both cases.
>>>
>>> The value I want to extract is the number of signal events under the Crystal Ball (CB) and the width of the Crystal Ball itself.
>>> Even if the fit quality is good in both cases, the number of events under the Crystal Ball is systematically different (~6-10% depending on the fit), as well as the CB width. In particular, ROOFIT gives always lower values. As an example:
>>>
>>> - ROOFIT: CB integral: 2090 +- 158, CB width: 72 MeV
>>> - ROOT: CB integral: 2220 +- 183, CB width: 76 MeV
>>>
>>> Do you have any suggestion? I'm using root v5.28.00d and in ROOT I use the options "LI".
>>> I attach to the mail the root file and two macro I use to perform the fit with root or roofit.
>>>
>>> Best regards and thanks in advance for your help,
>>>
>>> Roberta
>>> #ifndef __CINT__
>>> #include "RooGlobalFunc.h"
>>> #endif
>>> #include "RooRealVar.h"
>>> #include "RooDataSet.h"
>>> #include "RooGaussian.h"
>>> #include "RooExponential.h"
>>> #include "RooCBShape.h"
>>> #include "RooConstVar.h"
>>> #include "RooDataHist.h"
>>> #include "RooAddPdf.h"
>>> #include "RooWorkspace.h"
>>> #include "RooFitResult.h"
>>> #include "RooExtendPdf.h"
>>> #include "RooPlot.h"
>>> #include "TCanvas.h"
>>> #include "TAxis.h"
>>> #include "TStyle.h"
>>> #include "TFile.h"
>>> #include "TH1.h"
>>> using namespace RooFit ;
>>>
>>> void TestROOFIT(){
>>> gStyle->SetOptTitle(0) ;
>>> gStyle->SetOptStat(0) ;
>>> gStyle->SetPalette(1) ;
>>> gStyle->SetCanvasColor(10) ;
>>> gStyle->SetFrameFillColor(10) ;
>>>
>>> TFile *f = new TFile("Histo.root");
>>> TH1D *histo = (TH1D*) f->Get("histo");
>>> //------------------------------------
>>> // define x range and frame
>>> //------------------------------------
>>>
>>> RooRealVar x("DimuonMass","Mass",1.5,5.,"GeV/c^{2}") ;
>>> RooPlot* frame = x.frame(Title("Test Roofit")) ;
>>> TCanvas *c1 = new TCanvas("c1","c1",20,20,600,600);
>>> gPad->SetLogy(1);
>>>
>>> //------------------------------------
>>> // import histo //------------------------------------
>>>
>>> RooDataSet *datat; RooDataHist *datah;
>>> datah = new RooDataHist("datah","datah",x,Import(*histo));
>>> datah->plotOn(frame,Name("datah"),DataError(RooAbsData::SumW2),MarkerColor(kRed),MarkerSize(0.8),XErrorSize(0.)); datah->statOn(frame);
>>>
>>> //------------------------------------
>>> // define Crystal Ball
>>> //------------------------------------
>>> RooRealVar cbmean("cb mean","cb_mean",3.096,3.,3.13);
>>> RooRealVar cbsigma("cb sigma","cb_sigma",0.08,0.065,0.11);
>>> RooRealVar cbn("cb n","cb_n",3.6,0.1,100.);
>>> RooRealVar cbalpha("cb alpha","cb_alpha",1,0.1,10.);
>>> RooCBShape cb("cb","cb",x,cbmean,cbsigma,cbalpha,cbn) ;
>>>
>>> cbalpha.setVal(0.98); cbalpha.setConstant(kTRUE);
>>> cbn.setVal(5.2); cbn.setConstant(kTRUE);
>>> //----------------------------------------------------
>>> // fit expo1 //-----------------------------------------------------
>>>
>>> RooRealVar alpha1("bck1 alpha","bck1_alpha",-2.282635,-5.,0.) ;
>>> RooRealVar nbck1("nbck1","nbck1",500,0.,1e10);
>>> RooExponential exp1("exp1","exp1",x,alpha1) ;
>>> x.setRange("rangeBck1",1.5,2.7);
>>> RooExtendPdf ebck1_step1("ebck1_step1","ebck1_step1",exp1,nbck1);
>>> RooAddPdf bck1_step1("bck1_step1","exp bck1",RooArgList(ebck1_step1));
>>>
>>> //-----------------------------------------------------
>>> // fit expo2 // -----------------------------------------------------
>>> RooRealVar alpha2("bck2 alpha","bck2_alpha",-0.559789,-10.,0.) ;
>>> RooRealVar nbck2("nbck2","nbck2",500,0.,1e10);
>>> RooExponential exp2("exp2","exp2",x,alpha2) ;
>>> RooExtendPdf ebck2_step1("ebck2_step1","ebck2_step1",exp2,nbck2);
>>> RooAddPdf bck2_step1("bck2_step1","exp bck2",RooArgList(ebck2_step1));
>>> x.setRange("rangeBck2",3.5,5.);
>>>
>>> //------------------------------------ ----------------
>>> // define expo1+expo2
>>> //-----------------------------------------------------
>>> RooAddPdf bck("bck","exp1+exp2",RooArgList(ebck1_step1,ebck2_step1));
>>> //------------------------------------
>>> // fit with signal+bck
>>> //------------------------------------
>>>
>>> RooRealVar nsig("N.JPsi","nsignal",500,0.,1000000);
>>> RooExtendPdf esig("esig","esig",cb,nsig);
>>> RooAddPdf sum("sum","bck1+bck2+cb",RooArgList(esig,ebck1_step1,ebck2_step1));
>>> RooFitResult* r;
>>> x.setRange("fitrange",2.,5.);
>>> r = sum.fitTo(*datah,Range("fitrange"),Extended(kTRUE),Save()) ;
>>>
>>> //------------------------------------
>>> // plot
>>> //------------------------------------
>>> sum.plotOn(frame,Components("cb"),LineColor(kGreen)) ;
>>> sum.plotOn(frame,Components("exp1,exp2"),LineColor(kOrange)) ;
>>> sum.plotOn(frame,Name("sum"),LineColor(kBlue)) ; sum.paramOn(frame,Parameters(RooArgSet(cbmean,cbsigma,nsig)),Layout(0.6),Format("NELU",AutoPrecision(2)));
>>> frame->Draw() ;
>>>
>>> }
>>> <Histo.root>void TestROOT(){
>>>
>>> gStyle->SetOptStat(0);
>>> gStyle->SetOptTitle(0);
>>> gStyle->SetCanvasColor(10);
>>> gStyle->SetFrameFillColor(10);
>>>
>>> //----------------------------------------------------
>>> // Open file
>>> //----------------------------------------------------
>>> TFile *f = new TFile("Histo.root");
>>> TH1D *histo = (TH1D*) f->Get("histo"); TCanvas *c = new TCanvas("c","c",20,20,600,600);
>>> //----------------------------------------------------
>>> // Fit the invariant mass spectrum // with a Crystal Ball function + double exponential
>>> //----------------------------------------------------
>>> Double_t FitMin=2., FitMax=5.; TF1 *functot = new TF1("functot",FuncTot,FitMin,FitMax,9);
>>> functot->SetParameter(0,14.425808); // background parameters functot->SetParameter(1,-2.282635); // background parameters functot->SetParameter(2,6.466449); // background parameters functot->SetParameter(3,-0.559789); // background parameters functot->SetParameter(4,2859.295924); // JPsi normalization functot->SetParameter(5,3.130); // JPsi mass position functot->SetParameter(6,0.08); // JPsi width
>>> functot->FixParameter(7,0.98); // Crystal Ball tails
>>> functot->FixParameter(8,5.2); // Crystal Ball tails
>>> functot->SetLineColor(kBlue);
>>> functot->SetLineWidth(2);
>>>
>>> TFitResultPtr r = histo->Fit(functot,"RIlS");
>>>
>>> TMatrixDSym cov = r->GetCovarianceMatrix();
>>> Double_t *fullmat;
>>> fullmat = cov.GetMatrixArray();
>>> Double_t psimat[25];
>>> for(Int_t i=0;i<5;i++){
>>> for(Int_t j=0;j<5;j++) psimat[5*i+j]=fullmat[40+j+9*i];
>>> }
>>>
>>> histo->GetXaxis()->SetRangeUser(2.,5.);
>>> histo->SetMinimum(1.);
>>> gPad->SetLogy(1);
>>> histo->Draw("e");
>>> histo->SetMarkerStyle(20);
>>> histo->SetMarkerColor(2);
>>> histo->SetMarkerSize(0.7);
>>>
>>> TF1 *psifix = new TF1("psifix",FuncJpsi,0.,5.,9); for(int i=0;i<9;i++) psifix->SetParameter(i,functot->GetParameter(i));
>>> psifix->SetLineColor(kGreen);
>>> psifix->Draw("same");
>>> Double_t binWidth= histo->GetBinWidth(1);
>>> Double_t NPsi=psifix->Integral(0.,5.)/binWidth;
>>>
>>> TF1 *psifix2 = new TF1("psifix2",FuncJpsi2,0.,5.,5); for(int i=0;i<5;i++) psifix2->SetParameter(i,functot->GetParameter(i+4));
>>> Double_t psipar[5];
>>> for(int i=0;i<5;i++) psipar[i]=functot->GetParameter(4+i);
>>> Double_t ErrPsiCorrParam = psifix2->IntegralError(0.,5.,psipar,psimat)/binWidth;
>>>
>>> char text3[100];
>>> sprintf(text3,"N_{J/#psi}= %3.0f #pm %2.0f",NPsi,ErrPsiCorrParam);
>>> TLatex *l1 = new TLatex(3.35,psifix2->Integral(0.,5.)/binWidth*8/5.,text3);
>>> l1->Draw();
>>>
>>> char text5[100];
>>> sprintf(text5,"#sigma_{J/#psi}= %5.3f #pm %5.3f GeV/c^{2}",functot->GetParameter(6),functot->GetParError(6));
>>> TLatex *l3 = new TLatex(3.35,psifix2->Integral(0.,5.)/binWidth*0.3*5./1.5,text5);
>>> l3->SetTextSize(0.035);
>>> l3->Draw();
>>> }
>>>
>>> Double_t FuncJpsi(Double_t *x, Double_t *par){ //Crystal Ball
>>> Double_t FitJPsi;
>>> Double_t t = (x[0]-par[5])/par[6];
>>> if (t > (-par[7])){
>>> FitJPsi = par[4]*TMath::Exp(-t*t/2.);
>>> } else if (t <= (-par[7])) {
>>> Double_t AA = TMath::Power(par[8]/TMath::Abs(par[7]),par[8])*TMath::Exp(-TMath::Abs(par[7])*TMath::Abs(par[7])/2.);
>>> Double_t BB = par[8]/TMath::Abs(par[7])-TMath::Abs(par[7]);
>>> if(TMath::Power((BB-t),par[8])!=0){
>>> FitJPsi = par[4]*AA/TMath::Power((BB-t),par[8]);
>>> } else FitJPsi = 0;
>>> } return FitJPsi;
>>> }
>>>
>>> Double_t FuncJpsi2(Double_t *x, Double_t *par){ //Crystal Ball
>>> Double_t FitJPsi;
>>> Double_t t = (x[0]-par[1])/par[2];
>>> if (t > (-par[3])){
>>> FitJPsi = par[0]*TMath::Exp(-t*t/2.);
>>> } else if (t <= (-par[3])) {
>>> Double_t AA = TMath::Power(par[4]/TMath::Abs(par[3]),par[4])*TMath::Exp(-TMath::Abs(par[3])*TMath::Abs(par[3])/2.);
>>> Double_t BB = par[4]/TMath::Abs(par[3])-TMath::Abs(par[3]);
>>> if(TMath::Power((BB-t),par[4])!=0){
>>> FitJPsi = par[0]*AA/TMath::Power((BB-t),par[4]);
>>> } else FitJPsi = 0;
>>> } return FitJPsi;
>>> }
>>>
>>> Double_t FuncBck1(Double_t *x, Double_t *par){ //exponential
>>> Double_t FitBck1 = exp(par[0]+par[1]*x[0]);
>>> return FitBck1;
>>> }
>>> Double_t FuncBck2(Double_t *x, Double_t *par){ //exponential
>>> Double_t FitBck2 = exp(par[2]+par[3]*x[0]);
>>> return FitBck2;
>>> }
>>>
>>> Double_t FuncBck(Double_t *x, Double_t *par){ //exponential
>>> return FuncBck1(x,par)+FuncBck2(x,par);
>>> }
>>>
>>> Double_t FuncTot(Double_t *x, Double_t *par){ // total fit
>>> return FuncBck(x,par)+FuncJpsi(x,par);
>>> }
>>>
>>
>>
Received on Wed Jul 27 2011 - 22:39:07 CEST