UnbinnedFitDeDxEstimator.h

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#ifndef RecoTrackerDeDx_UnbinnedFitDeDxEstimator_h
#define RecoTrackerDeDx_UnbinnedFitDeDxEstimator_h

#include "DataFormats/TrackReco/interface/DeDxHit.h"
#include "RecoTracker/DeDx/interface/BaseDeDxEstimator.h"
#include "RecoTracker/DeDx/interface/DeDxTools.h"
#include "RecoTracker/DeDx/interface/UnbinnedLikelihoodFit.h"

#include <TF1.h>

#include <iostream>
#include <vector>

class UnbinnedFitDeDxEstimator : public BaseDeDxEstimator {
public:
  UnbinnedFitDeDxEstimator(const edm::ParameterSet& iConfig) {
    fitter.setFunction((f1 = new TF1("myLandau", "TMath::Landau(x,[0],[1],1)", 0, 255)));
  }

  ~UnbinnedFitDeDxEstimator() override {
    // clean up everything
    delete f1;
  }

  std::pair<float, float> dedx(const reco::DeDxHitCollection& Hits) override {
    // if there is no hit, returns invalid.
    if (Hits.empty())
      return std::make_pair(-1, -1);
    // sets the initial parameters
    f1->SetParameters(3.0, 0.3);
    // fills a temporary array and performs the fit
    uint32_t i = 0;
    for (reco::DeDxHitCollection::const_iterator hit = Hits.begin(); hit != Hits.end(); ++hit, ++i) {
      data[i] = hit->charge();
    }
    // fit !
    fitter.fit(Hits.size(), data);
    // returns the mpv and its error
    return std::make_pair(f1->GetParameter(0), f1->GetParError(0));
  }

  // ----------member data ---------------------------
  double data[50];
  TF1* f1;
  UnbinnedLikelihoodFit fitter;
};

#endif