fitting.cxx

#include "TFile.h"
#include "TTree.h"
#include "TCanvas.h"
#include "TF1.h"
#include "TH1F.h"
#include "TStyle.h"
#include "TLegend.h"
#include "TPaveStats.h"

void fitting()
{

	const Int_t bins = 200;

//	TFile *fr = new TFile("simeventsNew.root");
	TFile *fr = new TFile("simeventsNew1.root");

	TTree *tr = (TTree*)fr->Get("simevents");

	TCanvas *c1 = new TCanvas("name1", "title of canvas 1");
	c1->Divide(2,2);

	c1->cd(1);
	tr->Draw("E", "E>0");

	c1->cd(2);
	TH1F *hE = new TH1F("hE", "Interesting region", bins, 0.7, 1.3);
	tr->Draw("E>>hE", "E>0.7");


	c1->cd(3);
	TH1F *hEfitSep = new TH1F("hEfitSep", "Fit by two functions", bins, 0.7, 1.3);
	hE->Draw();
	tr->Draw("E >> hEfitSep", "", "");

	TF1 *g1 = new TF1("m1","gaus",0.9,1.05);
	TF1 *g2 = new TF1("m2","gaus",1.08,1.15);
	// The total is the sum of the three, each has 3 parameters
	TF1 *total = new TF1("mstotal","gaus(0)+gaus(3)",0.9,1.3);

	Double_t par[6];

	// Fit each function and add it to the list of functions
	hEfitSep->Fit(g1,"R");
	hEfitSep->Fit(g2,"R+");


	c1->cd(4);
	TH1F *hEtot = new TH1F("hEtot", "Fit by multiple function", bins, 0.7, 1.3);
	hEtot->Draw();
	tr->Draw("E >> hEtot", "", "");

	// Get the parameters from the fit
	g1->GetParameters(&par[0]);
	g2->GetParameters(&par[3]);

	// Use the parameters on the sum
	total->SetParameters(par);
	hEtot->Fit(total,"R+");

	TCanvas *c2 = new TCanvas("name2", "title of canvas 2");
	c2->Divide(2,2);

	c2->cd(1);
	TH1F *hEDecomposition = new TH1F(*hE);
	hEDecomposition->Draw();

	Double_t parTotal[6];
	total->GetParameters(&parTotal[0]);

	TF1 *gLow = new TF1("mLow","gaus",0.8,1.2);
	TF1 *gHigh = new TF1("mHigh","gaus",1.0,1.3);
	gHigh->SetLineColor(kGreen);

	gLow->SetParameter(0, parTotal[0]);
	gLow->SetParameter(1, parTotal[1]);
	gLow->SetParameter(2, parTotal[2]);

	gHigh->SetParameter(0, parTotal[3]);
	gHigh->SetParameter(1, parTotal[4]);
	gHigh->SetParameter(2, parTotal[5]);

	gLow->Draw("same");
	gHigh->Draw("same");

	c2->cd(2);
	hEtot->Draw();
	gHigh->Draw("same");

	c2->cd(3);
	TH1F *hInput = new TH1F(*hEDecomposition);
	hInput->SetName("hInput");
	tr->Draw("Egamma >> hInput", "");

	c2->cd(4);
//	TH1F *hEtotZoom = new TH1F(*hEtot);
	TH1F *hEtotZoom = (TH1F*)hEtot->Clone();
	hEtotZoom->SetName("hEtotZoom");
//	hEtotZoom->
	hEtotZoom->GetXaxis()->SetRangeUser(1.04, 1.18);
	hEtotZoom->Draw();
//	total->Draw("same");
	gHigh->Draw("same");

	Double_t maxSingle = gHigh->GetMaximumX(1.08, 1.14);
	Double_t maxTotal = total->GetMaximumX(1.08, 1.14);

//	cout << maxSingle << endl;

	TLine *l1 = new TLine(maxSingle, 100., maxSingle, 800.);
	l1->SetLineWidth(2);
	l1->SetLineColor(gHigh->GetLineColor());
	l1->Draw("");

	TLine *l2 = new TLine(maxTotal, 100., maxTotal, 800.);
	l2->SetLineWidth(2);
	l2->SetLineColor(total->GetLineColor());
	l2->Draw("");



}