/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_6_2_7/src/RecoBTag/SecondaryVertex/src/TrackKinematics.cc

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#include <cmath>
#include <vector>

#include <Math/GenVector/PxPyPzE4D.h>
#include <Math/GenVector/PxPyPzM4D.h>

#include "DataFormats/Math/interface/LorentzVector.h"
#include "DataFormats/TrackReco/interface/Track.h"
#include "DataFormats/VertexReco/interface/Vertex.h"

#include "RecoBTag/SecondaryVertex/interface/ParticleMasses.h"
#include "RecoBTag/SecondaryVertex/interface/TrackKinematics.h"

using namespace reco;

TrackKinematics::TrackKinematics() :
        n(0), sumWeights(0)
{
}

TrackKinematics::TrackKinematics(const std::vector<Track> &tracks) :
        n(0), sumWeights(0)
{
        for(std::vector<Track>::const_iterator iter = tracks.begin();
            iter != tracks.end(); iter++)
                add(*iter);
}

TrackKinematics::TrackKinematics(const TrackRefVector &tracks) :
        n(0), sumWeights(0)
{
        for(TrackRefVector::const_iterator iter = tracks.begin();
            iter != tracks.end(); iter++)
                add(**iter);
}

TrackKinematics::TrackKinematics(const Vertex &vertex) :
        n(0), sumWeights(0)
{
        bool hasRefittedTracks = vertex.hasRefittedTracks();
        for(Vertex::trackRef_iterator iter = vertex.tracks_begin();
            iter != vertex.tracks_end(); ++iter) {
                if (hasRefittedTracks)
                        add(vertex.refittedTrack(*iter),
                            vertex.trackWeight(*iter));
                else
                        add(**iter, vertex.trackWeight(*iter));
        }
}

TrackKinematics &TrackKinematics::operator += (const TrackKinematics &other)
{
        n += other.n;
        sumWeights += other.sumWeights;
        sum += other.sum;
        weightedSum += other.weightedSum;

        return *this;
}

void TrackKinematics::add(const Track &track, double weight)
{
        ROOT::Math::LorentzVector<ROOT::Math::PxPyPzM4D<double> > vec;

        vec.SetPx(track.px());
        vec.SetPy(track.py());
        vec.SetPz(track.pz());
        vec.SetM(ParticleMasses::piPlus);

        n++;
        sumWeights += weight;
        sum += vec;
        weightedSum += weight * vec;
}