DTResidualFitter.cc

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/*
 *  Fits core distribution to single gaussian; iterates once.  
 *
 *  \author A. Vilela Pereira
 */

#include "CalibMuon/DTCalibration/interface/DTResidualFitter.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include "TH1F.h"
#include "TF1.h"
#include "TString.h"

DTResidualFitter::DTResidualFitter(bool debug):debug_(debug) {}

DTResidualFitter::~DTResidualFitter() {}

DTResidualFitResult DTResidualFitter::fitResiduals(TH1F& histo, int nSigmas){
  
   TString option("R");
   if(!debug_) option += "Q";
 
   float under = histo.GetBinContent(0)/histo.GetEntries();
   float over = histo.GetBinContent(histo.GetNbinsX()+1)/histo.GetEntries();
   float minFit = histo.GetMean() - histo.GetRMS();
   float maxFit = histo.GetMean() + histo.GetRMS();

   if ((under>0.1) || (over>0.1))
     edm::LogError("DTResidualFitter") << "WARNING in histogram: " << histo.GetName() << "\n" 
                                       << "             entries: " << histo.GetEntries() << "\n"
                                       << "           underflow: " << under*100. << "% \n"
                                       << "            overflow: " << over*100. << "%";

   TString funcName = TString(histo.GetName()) + "_gaus";
   TF1* fitFunc = new TF1(funcName,"gaus",minFit,maxFit);

   histo.Fit(fitFunc,option);

   minFit = fitFunc->GetParameter(1) - nSigmas*fitFunc->GetParameter(2);
   maxFit = fitFunc->GetParameter(1) + nSigmas*fitFunc->GetParameter(2);
   fitFunc->SetRange(minFit,maxFit);
   histo.Fit(fitFunc,option);

   return DTResidualFitResult( fitFunc->GetParameter(1),
                               fitFunc->GetParError(1),
                               fitFunc->GetParameter(2),
                               fitFunc->GetParError(2) );
}