/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_6_2_5/src/TrackingTools/TrajectoryState/src/TrajectoryStateTransform.cc

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#include "TrackingTools/TrajectoryState/interface/TrajectoryStateTransform.h"
#include "DataFormats/TrackReco/interface/Track.h" 
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
#include "TrackingTools/TrajectoryState/interface/FreeTrajectoryState.h" 
#include "DataFormats/GeometrySurface/interface/Surface.h" 
#include "TrackingTools/TrajectoryParametrization/interface/GlobalTrajectoryParameters.h"
#include "Geometry/CommonDetUnit/interface/TrackingGeometry.h"
#include "Geometry/CommonDetUnit/interface/GeomDet.h"


namespace trajectoryStateTransform {

  using namespace SurfaceSideDefinition;
  
  PTrajectoryStateOnDet 
  persistentState( const TrajectoryStateOnSurface& ts,
                   unsigned int detid)
  {
    int surfaceSide = static_cast<int>(ts.surfaceSide());
    
    if (ts.hasError()) {
      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);
        }
      }
    return PTrajectoryStateOnDet(ts.localParameters(),
                                 localErrors, detid,
                                 surfaceSide);
    }
    return PTrajectoryStateOnDet(ts.localParameters(),
                                 detid,
                                 surfaceSide);
  }
  
  TrajectoryStateOnSurface 
  transientState( const PTrajectoryStateOnDet& ts,
                  const Surface* surface,
                  const MagneticField* field)
  {
    AlgebraicSymMatrix55 m;
    bool errInv=true;
    if (ts.hasError()) {
      errInv = false;
      int dim = 5;
      int k = 0;
      for (int i=0; i<dim; i++) {
        for (int j=0; j<=i; j++) {
          m(i,j) = ts.error(k++);       // NOTE: here we do a cast float => double.     
        }
      }
    }
    
    
    return TrajectoryStateOnSurface( ts.parameters(),
                                     errInv ? LocalTrajectoryError(InvalidError()) : LocalTrajectoryError(m),
                                     *surface, field,
                                     static_cast<SurfaceSide>(ts.surfaceSide()));
    
}
  
  FreeTrajectoryState initialFreeState( const reco::Track& tk,
                                        const MagneticField* field) 
  {
    Basic3DVector<float> pos( tk.vertex());
    GlobalPoint gpos( pos);
    Basic3DVector<float> mom( tk.momentum());
  GlobalVector gmom( mom);
  GlobalTrajectoryParameters par( gpos, gmom, tk.charge(), field);
  CurvilinearTrajectoryError err( tk.covariance());
  return FreeTrajectoryState( par, err);
  }
  
  FreeTrajectoryState innerFreeState( const reco::Track& tk,
                                      const MagneticField* field)
  {
    Basic3DVector<float> pos( tk.innerPosition());
    GlobalPoint gpos( pos);
    Basic3DVector<float> mom( tk.innerMomentum());
    GlobalVector gmom( mom);
    GlobalTrajectoryParameters par( gpos, gmom, tk.charge(), field);
    CurvilinearTrajectoryError err( tk.extra()->innerStateCovariance());
    return FreeTrajectoryState( par, err);
  }

  
  FreeTrajectoryState outerFreeState( const reco::Track& tk,
                                      const MagneticField* field)
  {
    Basic3DVector<float> pos( tk.outerPosition());
    GlobalPoint gpos( pos);
    Basic3DVector<float> mom( tk.outerMomentum());
    GlobalVector gmom( mom);
    GlobalTrajectoryParameters par( gpos, gmom, tk.charge(), field);
    CurvilinearTrajectoryError err( tk.extra()->outerStateCovariance());
    return FreeTrajectoryState( par, err);
  }

  
  TrajectoryStateOnSurface innerStateOnSurface( const reco::Track& tk, 
                                                const TrackingGeometry& geom,
                                                const MagneticField* field)
  {
    const Surface& surface = geom.idToDet( DetId( tk.extra()->innerDetId()))->surface();
    return TrajectoryStateOnSurface( innerFreeState( tk, field), surface);
  }
  
  TrajectoryStateOnSurface outerStateOnSurface( const reco::Track& tk, 
                                                const TrackingGeometry& geom,
                                                const MagneticField* field)
  {
    const Surface& surface = geom.idToDet( DetId( tk.extra()->outerDetId()))->surface();
    return TrajectoryStateOnSurface( outerFreeState( tk, field), surface);
  }
  
}