---

TrajectorySeedProducer.cc

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#include <memory>

#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Framework/interface/EventSetup.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/Framework/interface/ESHandle.h"

#include "DataFormats/Common/interface/Handle.h"
#include "DataFormats/Common/interface/OwnVector.h"
#include "DataFormats/TrackerRecHit2D/interface/SiTrackerGSRecHit2DCollection.h" 
#include "DataFormats/TrackerRecHit2D/interface/SiTrackerGSMatchedRecHit2DCollection.h" 
#include "DataFormats/TrajectorySeed/interface/TrajectorySeedCollection.h"
#include "DataFormats/BeamSpot/interface/BeamSpot.h"
#include "DataFormats/VertexReco/interface/Vertex.h"

#include "Geometry/TrackerGeometryBuilder/interface/TrackerGeometry.h"
#include "Geometry/Records/interface/TrackerDigiGeometryRecord.h"

#include "FastSimulation/ParticlePropagator/interface/MagneticFieldMapRecord.h"

#include "FastSimulation/Tracking/plugins/TrajectorySeedProducer.h"
#include "FastSimulation/Tracking/interface/TrackerRecHit.h"

#include "SimDataFormats/Track/interface/SimTrackContainer.h"
#include "SimDataFormats/Vertex/interface/SimVertexContainer.h"

#include "TrackingTools/TrajectoryParametrization/interface/CurvilinearTrajectoryError.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
#include "TrackingTools/TrajectoryState/interface/FreeTrajectoryState.h"

#include "Geometry/CommonDetUnit/interface/GeomDetUnit.h"
#include "DataFormats/DetId/interface/DetId.h"

#include "FastSimulation/BaseParticlePropagator/interface/BaseParticlePropagator.h"
#include "FastSimulation/ParticlePropagator/interface/ParticlePropagator.h"

//Propagator withMaterial
#include "TrackingTools/MaterialEffects/interface/PropagatorWithMaterial.h"
//analyticalpropagator
//#include "TrackingTools/GeomPropagators/interface/AnalyticalPropagator.h"


//

//for debug only 
//#define FAMOS_DEBUG

TrajectorySeedProducer::TrajectorySeedProducer(const edm::ParameterSet& conf)  :thePropagator(0)
{  

  // The input tag for the beam spot
  theBeamSpot = conf.getParameter<edm::InputTag>("beamSpot");

  // The name of the TrajectorySeed Collections
  seedingAlgo = conf.getParameter<std::vector<std::string> >("seedingAlgo");
  for ( unsigned i=0; i<seedingAlgo.size(); ++i )
    produces<TrajectorySeedCollection>(seedingAlgo[i]);

  // The smallest true pT for a track candidate
  pTMin = conf.getParameter<std::vector<double> >("pTMin");
  if ( pTMin.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : pTMin does not have the proper size "
      << std::endl;

  for ( unsigned i=0; i<pTMin.size(); ++i )
    pTMin[i] *= pTMin[i];  // Cut is done of perp2() - CPU saver
  
  // The smallest number of Rec Hits for a track candidate
  minRecHits = conf.getParameter<std::vector<unsigned int> >("minRecHits");
  if ( minRecHits.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : minRecHits does not have the proper size "
      << std::endl;
  // Set the overall number hits to be checked
  absMinRecHits = 0;
  for ( unsigned ialgo=0; ialgo<minRecHits.size(); ++ialgo ) 
    if ( minRecHits[ialgo] > absMinRecHits ) absMinRecHits = minRecHits[ialgo];

  // The smallest true impact parameters (d0 and z0) for a track candidate
  maxD0 = conf.getParameter<std::vector<double> >("maxD0");
  if ( maxD0.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : maxD0 does not have the proper size "
      << std::endl;

  maxZ0 = conf.getParameter<std::vector<double> >("maxZ0");
  if ( maxZ0.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : maxZ0 does not have the proper size "
      << std::endl;

  // The name of the hit producer
  hitProducer = conf.getParameter<edm::InputTag>("HitProducer");

  // The cuts for seed cleaning
  seedCleaning = conf.getParameter<bool>("seedCleaning");

  // Number of hits needed for a seed
  numberOfHits = conf.getParameter<std::vector<unsigned int> >("numberOfHits");
  if ( numberOfHits.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : numberOfHits does not have the proper size "
      << std::endl;

  //
  firstHitSubDetectorNumber = 
    conf.getParameter<std::vector<unsigned int> >("firstHitSubDetectorNumber");
  if ( firstHitSubDetectorNumber.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : firstHitSubDetectorNumber does not have the proper size "
      << std::endl;

  std::vector<unsigned int> firstSubDets = 
    conf.getParameter<std::vector<unsigned int> >("firstHitSubDetectors");
  unsigned isub1 = 0;
  unsigned check1 = 0;
  firstHitSubDetectors.resize(seedingAlgo.size());
  for ( unsigned ialgo=0; ialgo<firstHitSubDetectorNumber.size(); ++ialgo ) { 
    check1 += firstHitSubDetectorNumber[ialgo];
    for ( unsigned idet=0; idet<firstHitSubDetectorNumber[ialgo]; ++idet ) { 
      firstHitSubDetectors[ialgo].push_back(firstSubDets[isub1++]);
    }
  }
  if ( firstSubDets.size() != check1 ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : firstHitSubDetectors does not have the proper size (should be " << check1 << ")"
      << std::endl;


  secondHitSubDetectorNumber = 
    conf.getParameter<std::vector<unsigned int> >("secondHitSubDetectorNumber");
  if ( secondHitSubDetectorNumber.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : secondHitSubDetectorNumber does not have the proper size "
      << std::endl;

  std::vector<unsigned int> secondSubDets = 
    conf.getParameter<std::vector<unsigned int> >("secondHitSubDetectors");
  unsigned isub2 = 0;
  unsigned check2 = 0;
  secondHitSubDetectors.resize(seedingAlgo.size());
  for ( unsigned ialgo=0; ialgo<secondHitSubDetectorNumber.size(); ++ialgo ) { 
    check2 += secondHitSubDetectorNumber[ialgo];
    for ( unsigned idet=0; idet<secondHitSubDetectorNumber[ialgo]; ++idet ) { 
      secondHitSubDetectors[ialgo].push_back(secondSubDets[isub2++]);
    }
  }
  if ( secondSubDets.size() != check2 ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : secondHitSubDetectors does not have the proper size (should be " << check2 << ")"
      << std::endl;

  thirdHitSubDetectorNumber = 
    conf.getParameter<std::vector<unsigned int> >("thirdHitSubDetectorNumber");
  if ( thirdHitSubDetectorNumber.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : thirdHitSubDetectorNumber does not have the proper size "
      << std::endl;

  std::vector<unsigned int> thirdSubDets = 
    conf.getParameter<std::vector<unsigned int> >("thirdHitSubDetectors");
  unsigned isub3 = 0;
  unsigned check3 = 0;
  thirdHitSubDetectors.resize(seedingAlgo.size());
  for ( unsigned ialgo=0; ialgo<thirdHitSubDetectorNumber.size(); ++ialgo ) { 
    check3 += thirdHitSubDetectorNumber[ialgo];
    for ( unsigned idet=0; idet<thirdHitSubDetectorNumber[ialgo]; ++idet ) { 
      thirdHitSubDetectors[ialgo].push_back(thirdSubDets[isub3++]);
    }
  }
  if ( thirdSubDets.size() != check3 ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : thirdHitSubDetectors does not have the proper size (should be " << check3 << ")"
      << std::endl;

  originRadius = conf.getParameter<std::vector<double> >("originRadius");
  if ( originRadius.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : originRadius does not have the proper size "
      << std::endl;

  originHalfLength = conf.getParameter<std::vector<double> >("originHalfLength");
  if ( originHalfLength.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : originHalfLength does not have the proper size "
      << std::endl;

  originpTMin = conf.getParameter<std::vector<double> >("originpTMin");
  if ( originpTMin.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : originpTMin does not have the proper size "
      << std::endl;

  primaryVertices = conf.getParameter<std::vector<edm::InputTag> >("primaryVertices");
  if ( primaryVertices.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : primaryVertices does not have the proper size "
      << std::endl;

  zVertexConstraint = conf.getParameter<std::vector<double> >("zVertexConstraint");
  if ( zVertexConstraint.size() != seedingAlgo.size() ) 
    throw cms::Exception("FastSimulation/TrajectorySeedProducer ") 
      << " WARNING : zVertexConstraint does not have the proper size "
      << std::endl;

}

  
// Virtual destructor needed.
TrajectorySeedProducer::~TrajectorySeedProducer() {
  
  if(thePropagator) delete thePropagator;

  // do nothing
#ifdef FAMOS_DEBUG
  std::cout << "TrajectorySeedProducer destructed" << std::endl;
#endif

} 
 
void 
TrajectorySeedProducer::beginRun(edm::Run & run, const edm::EventSetup & es) {

  //services
  //  es.get<TrackerRecoGeometryRecord>().get(theGeomSearchTracker);

  edm::ESHandle<MagneticField>          magField;
  edm::ESHandle<TrackerGeometry>        geometry;
  edm::ESHandle<MagneticFieldMap>       magFieldMap;


  es.get<IdealMagneticFieldRecord>().get(magField);
  es.get<TrackerDigiGeometryRecord>().get(geometry);
  es.get<MagneticFieldMapRecord>().get(magFieldMap);

  theMagField = &(*magField);
  theGeometry = &(*geometry);
  theFieldMap = &(*magFieldMap);

  thePropagator = new PropagatorWithMaterial(alongMomentum,0.105,&(*theMagField)); 

  const GlobalPoint g(0.,0.,0.);

}
  
  // Functions that gets called by framework every event
void 
TrajectorySeedProducer::produce(edm::Event& e, const edm::EventSetup& es) {        

#ifdef FAMOS_DEBUG
  std::cout << "################################################################" << std::endl;
  std::cout << " TrajectorySeedProducer produce init " << std::endl;
#endif

  unsigned nSimTracks = 0;
  unsigned nTracksWithHits = 0;
  unsigned nTracksWithPT = 0;
  unsigned nTracksWithD0Z0 = 0;
  //  unsigned nTrackCandidates = 0;
  PTrajectoryStateOnDet initialState;
  
  // Output
  std::vector<TrajectorySeedCollection*>
    output(seedingAlgo.size(),static_cast<TrajectorySeedCollection*>(0));
  for ( unsigned ialgo=0; ialgo<seedingAlgo.size(); ++ialgo ) { 
    //    std::auto_ptr<TrajectorySeedCollection> p(new TrajectorySeedCollection );
    output[ialgo] = new TrajectorySeedCollection;
  }
  
  // Beam spot
  edm::Handle<reco::BeamSpot> recoBeamSpotHandle;
  e.getByLabel(theBeamSpot,recoBeamSpotHandle); 
  math::XYZPoint BSPosition_ = recoBeamSpotHandle->position();
  double sigmaZ=recoBeamSpotHandle->sigmaZ();
  double sigmaZ0Error=recoBeamSpotHandle->sigmaZ0Error();
  double sigmaz0=sqrt(sigmaZ*sigmaZ+sigmaZ0Error*sigmaZ0Error);
  x0 = BSPosition_.X();
  y0 = BSPosition_.Y();
  z0 = BSPosition_.Z();

  // SimTracks and SimVertices
  edm::Handle<edm::SimTrackContainer> theSimTracks;
  e.getByLabel("famosSimHits",theSimTracks);
  
  edm::Handle<edm::SimVertexContainer> theSimVtx;
  e.getByLabel("famosSimHits",theSimVtx);

#ifdef FAMOS_DEBUG
  std::cout << " Step A: SimTracks found " << theSimTracks->size() << std::endl;
#endif
  
  //  edm::Handle<SiTrackerGSRecHit2DCollection> theGSRecHits;
  edm::Handle<SiTrackerGSMatchedRecHit2DCollection> theGSRecHits;
  e.getByLabel(hitProducer, theGSRecHits);
  
  // No tracking attempted if no hits (but put an empty collection in the event)!
#ifdef FAMOS_DEBUG
  std::cout << " Step B: Full GS RecHits found " << theGSRecHits->size() << std::endl;
#endif
  if(theGSRecHits->size() == 0) {
    for ( unsigned ialgo=0; ialgo<seedingAlgo.size(); ++ialgo ) {
      std::auto_ptr<TrajectorySeedCollection> p(output[ialgo]);
      e.put(p,seedingAlgo[ialgo]);
    }
    return;
  }
  
  // Primary vertices
  vertices = std::vector<const reco::VertexCollection*>
    (seedingAlgo.size(),static_cast<const reco::VertexCollection*>(0));
  for ( unsigned ialgo=0; ialgo<seedingAlgo.size(); ++ialgo ) { 
    originHalfLength[ialgo] = 3.*sigmaz0; // Overrides the configuration
    edm::Handle<reco::VertexCollection> aHandle;
    bool isVertexCollection = e.getByLabel(primaryVertices[ialgo],aHandle);
    if (!isVertexCollection ) continue;
    vertices[ialgo] = &(*aHandle);
  }
  
#ifdef FAMOS_DEBUG
  std::cout << " Step C: Loop over the RecHits, track by track " << std::endl;
#endif

  // The vector of simTrack Id's carrying GSRecHits
  const std::vector<unsigned> theSimTrackIds = theGSRecHits->ids();

  // loop over SimTrack Id's
  for ( unsigned tkId=0;  tkId != theSimTrackIds.size(); ++tkId ) {

#ifdef FAMOS_DEBUG
    std::cout << "Track number " << tkId << std::endl;
#endif

    ++nSimTracks;
    unsigned simTrackId = theSimTrackIds[tkId];
    const SimTrack& theSimTrack = (*theSimTracks)[simTrackId]; 
#ifdef FAMOS_DEBUG
    std::cout << "Pt = " << std::sqrt(theSimTrack.momentum().Perp2()) 
              << " eta " << theSimTrack.momentum().Eta()
              << std::endl;
#endif
    
    // Check that the sim track comes from the main vertex (loose cut)
    int vertexIndex = theSimTrack.vertIndex();
    const SimVertex& theSimVertex = (*theSimVtx)[vertexIndex]; 
#ifdef FAMOS_DEBUG
    std::cout << " o SimTrack " << theSimTrack << std::endl;
    std::cout << " o SimVertex " << theSimVertex << std::endl;
#endif
    
    BaseParticlePropagator theParticle = 
      BaseParticlePropagator( 
         RawParticle(XYZTLorentzVector(theSimTrack.momentum().px(),
                                       theSimTrack.momentum().py(),
                                       theSimTrack.momentum().pz(),
                                       theSimTrack.momentum().e()),
                     XYZTLorentzVector(theSimVertex.position().x(),
                                       theSimVertex.position().y(),
                                       theSimVertex.position().z(),
                                       theSimVertex.position().t())),
                     0.,0.,4.);
    theParticle.setCharge((*theSimTracks)[simTrackId].charge());

    SiTrackerGSMatchedRecHit2DCollection::range theRecHitRange = theGSRecHits->get(simTrackId);
    SiTrackerGSMatchedRecHit2DCollection::const_iterator theRecHitRangeIteratorBegin = theRecHitRange.first;
    SiTrackerGSMatchedRecHit2DCollection::const_iterator theRecHitRangeIteratorEnd   = theRecHitRange.second;
    SiTrackerGSMatchedRecHit2DCollection::const_iterator iterRecHit;
    SiTrackerGSMatchedRecHit2DCollection::const_iterator iterRecHit1;
    SiTrackerGSMatchedRecHit2DCollection::const_iterator iterRecHit2;
    SiTrackerGSMatchedRecHit2DCollection::const_iterator iterRecHit3;

    // Check the number of layers crossed
    unsigned numberOfRecHits = 0;
    TrackerRecHit previousHit, currentHit;
    for ( iterRecHit = theRecHitRangeIteratorBegin; 
          iterRecHit != theRecHitRangeIteratorEnd; 
          ++iterRecHit) { 
      previousHit = currentHit;
      currentHit = TrackerRecHit(&(*iterRecHit),theGeometry);
      if ( currentHit.isOnTheSameLayer(previousHit) ) continue;
      ++numberOfRecHits;
      if ( numberOfRecHits == absMinRecHits ) break;
    }

    // Loop on the successive seedings
    for ( unsigned int ialgo = 0; ialgo < seedingAlgo.size(); ++ialgo ) { 

#ifdef FAMOS_DEBUG
      std::cout << "Algo " << seedingAlgo[ialgo] << std::endl;
#endif

      // Request a minimum number of RecHits for the track to give a seed.
#ifdef FAMOS_DEBUG
      std::cout << "The number of RecHits = " << numberOfRecHits << std::endl;
#endif
      if ( numberOfRecHits < minRecHits[ialgo] ) continue;
      ++nTracksWithHits;

      // Request a minimum pT for the sim track
      if ( theSimTrack.momentum().Perp2() < pTMin[ialgo] ) continue;
      ++nTracksWithPT;
      
      // Cut on sim track impact parameters
      if ( theParticle.xyImpactParameter(x0,y0) > maxD0[ialgo] ) continue;
      if ( fabs( theParticle.zImpactParameter(x0,y0) - z0 ) > maxZ0[ialgo] ) continue;
      ++nTracksWithD0Z0;
      
      std::vector<TrackerRecHit > 
        theSeedHits(numberOfHits[ialgo],
                    static_cast<TrackerRecHit >(TrackerRecHit()));
      TrackerRecHit& theSeedHits0 = theSeedHits[0];
      TrackerRecHit& theSeedHits1 = theSeedHits[1];
      TrackerRecHit& theSeedHits2 = theSeedHits[2];
      bool compatible = false;
      for ( iterRecHit1 = theRecHitRangeIteratorBegin; iterRecHit1 != theRecHitRangeIteratorEnd; ++iterRecHit1) {
        theSeedHits[0] = TrackerRecHit(&(*iterRecHit1),theGeometry);
#ifdef FAMOS_DEBUG
        std::cout << "The first hit position = " << theSeedHits0.globalPosition() << std::endl;
        std::cout << "The first hit subDetId = " << theSeedHits0.subDetId() << std::endl;
        std::cout << "The first hit layer    = " << theSeedHits0.layerNumber() << std::endl;
#endif

        // Check if inside the requested detectors
        bool isInside = theSeedHits0.subDetId() < firstHitSubDetectors[ialgo][0];
        if ( isInside ) continue;

        // Check if on requested detectors
        bool isOndet =  theSeedHits0.isOnRequestedDet(firstHitSubDetectors[ialgo]);
        if ( !isOndet ) break;

#ifdef FAMOS_DEBUG
        std::cout << "Apparently the first hit is on the requested detector! " << std::endl;
#endif
        for ( iterRecHit2 = iterRecHit1+1; iterRecHit2 != theRecHitRangeIteratorEnd; ++iterRecHit2) {
          theSeedHits[1] = TrackerRecHit(&(*iterRecHit2),theGeometry);
#ifdef FAMOS_DEBUG
          std::cout << "The second hit position = " << theSeedHits1.globalPosition() << std::endl;
          std::cout << "The second hit subDetId = " << theSeedHits1.subDetId() << std::endl;
          std::cout << "The second hit layer    = " << theSeedHits1.layerNumber() << std::endl;
#endif

          // Check if inside the requested detectors
          isInside = theSeedHits1.subDetId() < secondHitSubDetectors[ialgo][0];
          if ( isInside ) continue;

          // Check if on requested detectors
          isOndet =  theSeedHits1.isOnRequestedDet(secondHitSubDetectors[ialgo]);
          if ( !isOndet ) break;

          // Check if on the same layer as previous hit
          if ( theSeedHits1.isOnTheSameLayer(theSeedHits0) ) continue;

#ifdef FAMOS_DEBUG
          std::cout << "Apparently the second hit is on the requested detector! " << std::endl;
#endif
          GlobalPoint gpos1 = theSeedHits0.globalPosition();
          GlobalPoint gpos2 = theSeedHits1.globalPosition();
          bool forward = theSeedHits0.isForward();
          double error = std::sqrt(theSeedHits0.largerError()+theSeedHits1.largerError());
          //      compatible = compatibleWithVertex(gpos1,gpos2,ialgo);
          compatible = compatibleWithBeamAxis(gpos1,gpos2,error,forward,ialgo);
#ifdef FAMOS_DEBUG
          std::cout << "Are the two hits compatible with the PV? " << compatible << std::endl;
#endif

          // Check if the pair is on the requested dets
          if ( numberOfHits[ialgo] == 2 ) compatible = compatible && theSeedHits[0].makesAPairWith(theSeedHits[1]);

          // Reject non suited pairs
          if ( !compatible ) continue;

#ifdef FAMOS_DEBUG
          std::cout << "Pair kept! " << std::endl;
#endif

          // Leave here if only two hits are required.
          if ( numberOfHits[ialgo] == 2 ) break; 
          
          compatible = false;
          // Check if there is a third satisfying hit otherwise
          for ( iterRecHit3 = iterRecHit2+1; iterRecHit3 != theRecHitRangeIteratorEnd; ++iterRecHit3) {
            theSeedHits[2] = TrackerRecHit(&(*iterRecHit3),theGeometry);
#ifdef FAMOS_DEBUG
            std::cout << "The third hit position = " << theSeedHits2.globalPosition() << std::endl;
            std::cout << "The third hit subDetId = " << theSeedHits2.subDetId() << std::endl;
            std::cout << "The third hit layer    = " << theSeedHits2.layerNumber() << std::endl;
#endif

            // Check if inside the requested detectors
            isInside = theSeedHits2.subDetId() < thirdHitSubDetectors[ialgo][0];
            if ( isInside ) continue;
            
            // Check if on requested detectors
            isOndet =  theSeedHits2.isOnRequestedDet(thirdHitSubDetectors[ialgo]);
            if ( !isOndet ) break;

            // Check if on the same layer as previous hit
            compatible = !(theSeedHits2.isOnTheSameLayer(theSeedHits1));

            // Check if the triplet is on the requested det combination
            compatible = compatible && theSeedHits[0].makesATripletWith(theSeedHits[1],theSeedHits[2]);

#ifdef FAMOS_DEBUG
            if ( compatible ) 
              std::cout << "Apparently the third hit is on the requested detector! " << std::endl;
#endif

            if ( compatible ) break;      

          }

          if ( compatible ) break;

        }

        if ( compatible ) break;

      }

      // There is no compatible seed for this track with this seeding algorithm 
      // Go to next algo
      if ( !compatible ) continue;

#ifdef FAMOS_DEBUG
      std::cout << "Preparing to create the TrajectorySeed" << std::endl;
#endif
      // The seed is validated -> include in the collection
      // 1) Create the vector of RecHits
      edm::OwnVector<TrackingRecHit> recHits;
      for ( unsigned ih=0; ih<theSeedHits.size(); ++ih ) {
        TrackingRecHit* aTrackingRecHit = theSeedHits[ih].hit()->clone();
        recHits.push_back(aTrackingRecHit);
      }
#ifdef FAMOS_DEBUG
      std::cout << "with " << recHits.size() << " hits." << std::endl;
#endif

      // 2) Create the initial state
      //   a) origin vertex
      GlobalPoint  position((*theSimVtx)[vertexIndex].position().x(),
                            (*theSimVtx)[vertexIndex].position().y(),
                            (*theSimVtx)[vertexIndex].position().z());
      
      //   b) initial momentum
      GlobalVector momentum( (*theSimTracks)[simTrackId].momentum().x() , 
                             (*theSimTracks)[simTrackId].momentum().y() , 
                             (*theSimTracks)[simTrackId].momentum().z() );
      //   c) electric charge
      float        charge   = (*theSimTracks)[simTrackId].charge();
      //  -> inital parameters
      GlobalTrajectoryParameters initialParams(position,momentum,(int)charge,theMagField);
      //  -> large initial errors
      AlgebraicSymMatrix errorMatrix(5,1);      
      // errorMatrix = errorMatrix * 10;
#ifdef FAMOS_DEBUG
      std::cout << "TrajectorySeedProducer: SimTrack parameters " << std::endl;
      std::cout << "\t\t pT  = " << (*theSimTracks)[simTrackId].momentum().Pt() << std::endl;
      std::cout << "\t\t eta = " << (*theSimTracks)[simTrackId].momentum().Eta()  << std::endl;
      std::cout << "\t\t phi = " << (*theSimTracks)[simTrackId].momentum().Phi()  << std::endl;
      std::cout << "TrajectorySeedProducer: AlgebraicSymMatrix " << errorMatrix << std::endl;
#endif
      CurvilinearTrajectoryError initialError(errorMatrix);
      // -> initial state
      FreeTrajectoryState initialFTS(initialParams, initialError);      
#ifdef FAMOS_DEBUG
      std::cout << "TrajectorySeedProducer: FTS momentum " << initialFTS.momentum() << std::endl;
#endif
      // const GeomDetUnit* initialLayer = theGeometry->idToDetUnit( recHits.front().geographicalId() );
      const GeomDet* initialLayer = theGeometry->idToDet( recHits.front().geographicalId() );

      //this is wrong because the FTS is defined at vertex, and it need to be properly propagated.
      //      const TrajectoryStateOnSurface initialTSOS(initialFTS, initialLayer->surface());      

      const TrajectoryStateOnSurface initialTSOS = thePropagator->propagate(initialFTS,initialLayer->surface()) ;
      if (!initialTSOS.isValid()) continue; 

#ifdef FAMOS_DEBUG
      std::cout << "TrajectorySeedProducer: TSOS global momentum "    << initialTSOS.globalMomentum() << std::endl;
      std::cout << "\t\t\tpT = "                                     << initialTSOS.globalMomentum().perp() << std::endl;
      std::cout << "\t\t\teta = "                                    << initialTSOS.globalMomentum().eta() << std::endl;
      std::cout << "\t\t\tphi = "                                    << initialTSOS.globalMomentum().phi() << std::endl;
      std::cout << "TrajectorySeedProducer: TSOS local momentum "     << initialTSOS.localMomentum()  << std::endl;
      std::cout << "TrajectorySeedProducer: TSOS local error "        << initialTSOS.localError().positionError() << std::endl;
      std::cout << "TrajectorySeedProducer: TSOS local error matrix " << initialTSOS.localError().matrix() << std::endl;
      std::cout << "TrajectorySeedProducer: TSOS surface side "       << initialTSOS.surfaceSide()    << std::endl;
#endif
      stateOnDet(initialTSOS, 
                 recHits.front().geographicalId().rawId(),
                 initialState);
      // Create a new Trajectory Seed    
      output[ialgo]->push_back(TrajectorySeed(initialState, recHits, alongMomentum));
#ifdef FAMOS_DEBUG
      std::cout << "Trajectory seed created ! " << std::endl;
#endif
      break;
      // End of the loop over seeding algorithms
    }
    // End on the loop over simtracks
  }

  for ( unsigned ialgo=0; ialgo<seedingAlgo.size(); ++ialgo ) { 
    std::auto_ptr<TrajectorySeedCollection> p(output[ialgo]);
    e.put(p,seedingAlgo[ialgo]);
  }

}

// This is a copy of a method in 
// TrackingTools/TrajectoryState/src/TrajectoryStateTransform.cc
// but it does not return a pointer (thus avoiding a memory leak)
// In addition, it's also CPU more efficient, because 
// ts.localError().matrix() is not copied
void 
TrajectorySeedProducer::stateOnDet(const TrajectoryStateOnSurface& ts,
                                   unsigned int detid,
                                   PTrajectoryStateOnDet& pts) const
{

  const AlgebraicSymMatrix55& m = ts.localError().matrix();
  
  int dim = 5; 

  float localErrors[15];
  int k = 0;
  for (int i=0; i<dim; ++i) {
    for (int j=0; j<=i; ++j) {
      localErrors[k++] = m(i,j);
    }
  }
  int surfaceSide = static_cast<int>(ts.surfaceSide());

  pts = PTrajectoryStateOnDet( ts.localParameters(),
                               localErrors, detid,
                               surfaceSide);
}

bool
TrajectorySeedProducer::compatibleWithBeamAxis(GlobalPoint& gpos1, 
                                               GlobalPoint& gpos2,
                                               double error,
                                               bool forward,
                                               unsigned algo) const {

  if ( !seedCleaning ) return true;

  // The hits 1 and 2 positions, in HepLorentzVector's
  XYZTLorentzVector thePos1(gpos1.x(),gpos1.y(),gpos1.z(),0.);
  XYZTLorentzVector thePos2(gpos2.x(),gpos2.y(),gpos2.z(),0.);
#ifdef FAMOS_DEBUG
  std::cout << "ThePos1 = " << thePos1 << std::endl;
  std::cout << "ThePos2 = " << thePos2 << std::endl;
#endif


  // Create new particles that pass through the second hit with pT = ptMin 
  // and charge = +/-1
  
  // The momentum direction is by default joining the two hits 
  XYZTLorentzVector theMom2 = (thePos2-thePos1);

  // The corresponding RawParticle, with an (irrelevant) electric charge
  // (The charge is determined in the next step)
  ParticlePropagator myPart(theMom2,thePos2,1.,theFieldMap);

  bool intersect = myPart.propagateToBeamCylinder(thePos1,originRadius[algo]*1.);
  if ( !intersect ) return false;

#ifdef FAMOS_DEBUG
  std::cout << "MyPart R = " << myPart.R() << "\t Z = " << myPart.Z() 
            << "\t pT = " << myPart.Pt() << std::endl;
#endif

  // Check if the constraints are satisfied
  // 1. pT at cylinder with radius originRadius
  if ( myPart.Pt() < originpTMin[algo] ) return false;

  // 2. Z compatible with beam spot size
  if ( fabs(myPart.Z()-z0) > originHalfLength[algo] ) return false;

  // 3. Z compatible with one of the primary vertices (always the case if no primary vertex)
  const reco::VertexCollection* theVertices = vertices[algo];
  if (!theVertices) return true;
  unsigned nVertices = theVertices->size();
  if ( !nVertices || zVertexConstraint[algo] < 0. ) return true;
  // Radii of the two hits with respect to the beam spot position
  double R1 = std::sqrt ( (thePos1.X()-x0)*(thePos1.X()-x0) 
                        + (thePos1.Y()-y0)*(thePos1.Y()-y0) );
  double R2 = std::sqrt ( (thePos2.X()-x0)*(thePos2.X()-x0) 
                        + (thePos2.Y()-y0)*(thePos2.Y()-y0) );
  // Loop on primary vertices
  for ( unsigned iv=0; iv<nVertices; ++iv ) { 
    // Z position of the primary vertex
    double zV = (*theVertices)[iv].z();
    // Constraints on the inner hit
    double checkRZ1 = forward ?
      (thePos1.Z()-zV+zVertexConstraint[algo]) / (thePos2.Z()-zV+zVertexConstraint[algo]) * R2 : 
      -zVertexConstraint[algo] + R1/R2*(thePos2.Z()-zV+zVertexConstraint[algo]);
    double checkRZ2 = forward ?
      (thePos1.Z()-zV-zVertexConstraint[algo])/(thePos2.Z()-zV-zVertexConstraint[algo]) * R2 :
      +zVertexConstraint[algo] + R1/R2*(thePos2.Z()-zV-zVertexConstraint[algo]);
    double checkRZmin = std::min(checkRZ1,checkRZ2)-3.*error;
    double checkRZmax = std::max(checkRZ1,checkRZ2)+3.*error;
    // Check if the innerhit is within bounds
    bool compat = forward ?
      checkRZmin < R1 && R1 < checkRZmax : 
      checkRZmin < thePos1.Z()-zV && thePos1.Z()-zV < checkRZmax; 
    // If it is, just return ok
    if ( compat ) return compat;
  }
  // Otherwise, return not ok
  return false;

}  

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