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));
}