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145 lines
4.1 KiB
145 lines
4.1 KiB
//+ Combined (simultaneous) fit of two histogram with separate functions
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// and some common parameters
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//
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// See http://root.cern.ch/phpBB3//viewtopic.php?f=3&t=11740#p50908
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// for a modified version working with Fumili or GSLMultiFit
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//
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// N.B. this macro must be compiled with ACliC
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//
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//Author: L. Moneta - Dec 2010
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#include "Fit/Fitter.h"
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#include "Fit/BinData.h"
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#include "Fit/Chi2FCN.h"
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#include "TH1.h"
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#include "TList.h"
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#include "Math/WrappedMultiTF1.h"
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#include "HFitInterface.h"
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#include "TCanvas.h"
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#include "TStyle.h"
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// definition of shared parameter
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// background function
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int iparB[2] = { 0, // exp amplitude in B histo
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2 // exp common parameter
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};
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// signal + background function
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int iparSB[5] = { 1, // exp amplitude in S+B histo
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2, // exp common parameter
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3, // gaussian amplitude
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4, // gaussian mean
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5 // gaussian sigma
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};
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struct GlobalChi2 {
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GlobalChi2( ROOT::Math::IMultiGenFunction & f1,
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ROOT::Math::IMultiGenFunction & f2) :
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fChi2_1(&f1), fChi2_2(&f2) {}
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// parameter vector is first background (in common 1 and 2)
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// and then is signal (only in 2)
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double operator() (const double *par) const {
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double p1[2];
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for (int i = 0; i < 2; ++i) p1[i] = par[iparB[i] ];
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double p2[5];
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for (int i = 0; i < 5; ++i) p2[i] = par[iparSB[i] ];
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return (*fChi2_1)(p1) + (*fChi2_2)(p2);
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}
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const ROOT::Math::IMultiGenFunction * fChi2_1;
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const ROOT::Math::IMultiGenFunction * fChi2_2;
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};
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void combinedFit() {
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#if defined(__CINT__) && !defined(__MAKECINT__)
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cout << "ERROR: This tutorial can run only using ACliC, you must run it by doing: " << endl;
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cout << "\t .x $ROOTSYS/tutorials/fit/combinedFit.C+" << endl;
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return;
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#endif
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TH1D * hB = new TH1D("hB","histo B",100,0,100);
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TH1D * hSB = new TH1D("hSB","histo S+B",100, 0,100);
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TF1 * fB = new TF1("fB","expo",0,100);
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fB->SetParameters(1,-0.05);
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hB->FillRandom("fB");
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TF1 * fS = new TF1("fS","gaus",0,100);
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fS->SetParameters(1,30,5);
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hSB->FillRandom("fB",2000);
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hSB->FillRandom("fS",1000);
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// perform now global fit
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TF1 * fSB = new TF1("fSB","expo + gaus(2)",0,100);
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ROOT::Math::WrappedMultiTF1 wfB(*fB,1);
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ROOT::Math::WrappedMultiTF1 wfSB(*fSB,1);
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ROOT::Fit::DataOptions opt;
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ROOT::Fit::DataRange rangeB;
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// set the data range
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rangeB.SetRange(10,90);
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ROOT::Fit::BinData dataB(opt,rangeB);
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ROOT::Fit::FillData(dataB, hB);
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ROOT::Fit::DataRange rangeSB;
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rangeSB.SetRange(10,50);
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ROOT::Fit::BinData dataSB(opt,rangeSB);
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ROOT::Fit::FillData(dataSB, hSB);
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ROOT::Fit::Chi2Function chi2_B(dataB, wfB);
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ROOT::Fit::Chi2Function chi2_SB(dataSB, wfSB);
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GlobalChi2 globalChi2(chi2_B, chi2_SB);
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ROOT::Fit::Fitter fitter;
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const int Npar = 6;
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double par0[Npar] = { 5,5,-0.1,100, 30,10};
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// create before the parameter settings in order to fix or set range on them
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fitter.Config().SetParamsSettings(6,par0);
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// fix 5-th parameter
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fitter.Config().ParSettings(4).Fix();
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// set limits on the third and 4-th parameter
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fitter.Config().ParSettings(2).SetLimits(-10,-1.E-4);
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fitter.Config().ParSettings(3).SetLimits(0,10000);
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fitter.Config().ParSettings(3).SetStepSize(5);
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fitter.Config().MinimizerOptions().SetPrintLevel(0);
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fitter.Config().SetMinimizer("Minuit2","Migrad");
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// fit FCN function directly
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// (specify optionally data size and flag to indicate that is a chi2 fit)
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fitter.FitFCN(6,globalChi2,0,dataB.Size()+dataSB.Size(),true);
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ROOT::Fit::FitResult result = fitter.Result();
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result.Print(std::cout);
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TCanvas * c1 = new TCanvas("Simfit","Simultaneous fit of two histograms",
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10,10,700,700);
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c1->Divide(1,2);
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c1->cd(1);
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gStyle->SetOptFit(1111);
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fB->SetFitResult( result, iparB);
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fB->SetRange(rangeB().first, rangeB().second);
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fB->SetLineColor(kBlue);
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hB->GetListOfFunctions()->Add(fB);
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hB->Draw();
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c1->cd(2);
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fSB->SetFitResult( result, iparSB);
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fSB->SetRange(rangeSB().first, rangeSB().second);
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fSB->SetLineColor(kRed);
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hSB->GetListOfFunctions()->Add(fSB);
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hSB->Draw();
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}
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