AnalyticalPropagator.cc

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#include "TrackingTools/GeomPropagators/interface/AnalyticalPropagator.h"

#include "DataFormats/GeometrySurface/interface/Cylinder.h"
#include "DataFormats/GeometrySurface/interface/TangentPlane.h"
#include "DataFormats/GeometrySurface/interface/Plane.h"

#include "MagneticField/Engine/interface/MagneticField.h"

#include "TrackingTools/GeomPropagators/interface/PropagationExceptions.h"
#include "TrackingTools/GeomPropagators/interface/StraightLinePlaneCrossing.h"
#include "TrackingTools/GeomPropagators/interface/StraightLineBarrelCylinderCrossing.h"
#include "TrackingTools/GeomPropagators/interface/HelixBarrelPlaneCrossingByCircle.h"
#include "TrackingTools/GeomPropagators/interface/HelixForwardPlaneCrossing.h"
#include "TrackingTools/GeomPropagators/interface/HelixArbitraryPlaneCrossing.h"
#include "TrackingTools/GeomPropagators/interface/HelixBarrelCylinderCrossing.h"
#include "TrackingTools/AnalyticalJacobians/interface/AnalyticalCurvilinearJacobian.h"
#include "TrackingTools/GeomPropagators/interface/PropagationDirectionFromPath.h"
#include "TrackingTools/TrajectoryState/interface/SurfaceSideDefinition.h"
#include "TrackingTools/GeomPropagators/interface/PropagationExceptions.h"

#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include <cmath>

using namespace SurfaceSideDefinition;

std::pair<TrajectoryStateOnSurface,double>
AnalyticalPropagator::propagateWithPath(const FreeTrajectoryState& fts, 
                    const Plane& plane) const
{
  // check curvature
  float rho = fts.transverseCurvature();
  
  // propagate parameters
  GlobalPoint x;
  GlobalVector p;
  double s;
  
  // check if already on plane
  if likely (plane.localZclamped(fts.position()) !=0)  {
      // propagate
      bool parametersOK = this->propagateParametersOnPlane(fts, plane, x, p, s);
      // check status and deltaPhi limit
      float dphi2 = float(s)*rho;
      dphi2 = dphi2*dphi2*fts.momentum().perp2();
      if unlikely( !parametersOK || dphi2>theMaxDPhi2*fts.momentum().mag2() )  return TsosWP(TrajectoryStateOnSurface(),0.);
    }
  else {
    LogDebug("AnalyticalPropagator")<<"not going anywhere. Already on surface.\n"
                    <<"plane.localZ(fts.position()): "<<plane.localZ(fts.position())<<"\n"
                    <<"plane.position().mag(): "<<plane.position().mag() <<"\n"
                    <<"plane.posPrec: "<<plane.posPrec();
    x = fts.position();
    p = fts.momentum();
    s = 0;
  }
  //
  // Compute propagated state and check change in curvature
  //
  GlobalTrajectoryParameters gtp(x,p,fts.charge(),theField);
  if unlikely(std::abs(gtp.transverseCurvature()-rho)>theMaxDBzRatio*std::abs(rho) ) 
    return TsosWP(TrajectoryStateOnSurface(),0.);
  //
  // construct TrajectoryStateOnSurface
  //
  return propagatedStateWithPath(fts,plane,gtp,s);
}


std::pair<TrajectoryStateOnSurface,double>
AnalyticalPropagator::propagateWithPath(const FreeTrajectoryState& fts, 
                    const Cylinder& cylinder) const
{
  // check curvature
  double rho = fts.transverseCurvature();

  // propagate parameters
  GlobalPoint x;
  GlobalVector p;
  double s = 0;

  bool parametersOK = this->propagateParametersOnCylinder(fts, cylinder, x, p, s);
  // check status and deltaPhi limit
  float dphi2 = s*rho;
  dphi2 = dphi2*dphi2*fts.momentum().perp2();
  if unlikely( !parametersOK || dphi2>theMaxDPhi2*fts.momentum().mag2() )  return TsosWP(TrajectoryStateOnSurface(),0.);
  //
  // Compute propagated state and check change in curvature
  //
  GlobalTrajectoryParameters gtp(x,p,fts.charge(),theField);
  if unlikely( std::abs(gtp.transverseCurvature()-rho)>theMaxDBzRatio*std::abs(rho) ) 
    return TsosWP(TrajectoryStateOnSurface(),0.);
  //
  // create result TSOS on TangentPlane (local parameters & errors are better defined)
  //

  //try {
    ReferenceCountingPointer<TangentPlane> plane(cylinder.tangentPlane(x));  // need to be here until tsos is created!
    return propagatedStateWithPath(fts,*plane,gtp,s);
  /*
  } catch(...) {
    std::cout << "wrong tangent to cylinder " << x 
              << " pos, rad " << cylinder.position() << " " << cylinder.radius()
              << std::endl;
    return TsosWP(TrajectoryStateOnSurface(),0.);
  }
  */
}

std::pair<TrajectoryStateOnSurface,double>
AnalyticalPropagator::propagatedStateWithPath (const FreeTrajectoryState& fts, 
                           const Surface& surface, 
                           const GlobalTrajectoryParameters& gtp, 
                           const double& s) const
{
  //
  // for forward propagation: state is before surface,
  // for backward propagation: state is after surface
  //
  SurfaceSide side = PropagationDirectionFromPath()(s,propagationDirection())==alongMomentum 
    ? beforeSurface : afterSurface;
  // 
  //
  // error propagation (if needed) and conversion to a TrajectoryStateOnSurface
  //
  if (fts.hasError()) {
    //
    // compute jacobian
    //
    AnalyticalCurvilinearJacobian analyticalJacobian(fts.parameters(), gtp.position(), gtp.momentum(), s);
    const AlgebraicMatrix55 &jacobian = analyticalJacobian.jacobian();
    CurvilinearTrajectoryError cte(ROOT::Math::Similarity(jacobian, fts.curvilinearError().matrix()));
    return TsosWP(TrajectoryStateOnSurface(gtp,cte,surface,side),s);
  }
  else {
    //
    // return state without errors
    //
    return TsosWP(TrajectoryStateOnSurface(gtp,surface,side),s);
  }
}

bool AnalyticalPropagator::propagateParametersOnCylinder(
  const FreeTrajectoryState& fts, const Cylinder& cylinder, 
  GlobalPoint& x, GlobalVector& p, double& s) const
{

  GlobalPoint const & sp = cylinder.position();
  if (sp.x()!=0. || sp.y()!=0.) {
    throw PropagationException("Cannot propagate to an arbitrary cylinder");
  }
  // preset output
  x = fts.position();
  p = fts.momentum();
  s = 0;
  // (transverse) curvature
  double rho = fts.transverseCurvature();
  //
  // Straight line approximation? |rho|<1.e-10 equivalent to ~ 1um 
  // difference in transversal position at 10m.
  //
  if( fabs(rho)<1.e-10 )
    return propagateWithLineCrossing(fts.position(),p,cylinder,x,s);
  //
  // Helix case
  //
  // check for possible intersection
  const double tolerance = 1.e-4; // 1 micron distance
  double rdiff = x.perp() - cylinder.radius();
  if ( fabs(rdiff) < tolerance )  return true;
  //
  // Instantiate HelixBarrelCylinderCrossing and get solutions
  //
  HelixBarrelCylinderCrossing cylinderCrossing(fts.position(),fts.momentum(),rho,
                           propagationDirection(),cylinder);
  if ( !cylinderCrossing.hasSolution() )  return false;
  // path length
  s = cylinderCrossing.pathLength();
  // point
  x = cylinderCrossing.position();
  // direction (renormalised)
  p = cylinderCrossing.direction().unit()*fts.momentum().mag();
  return true;
}
  
bool 
AnalyticalPropagator::propagateParametersOnPlane(const FreeTrajectoryState& fts, 
                         const Plane& plane, 
                         GlobalPoint& x, 
                         GlobalVector& p, 
                         double& s) const
{
  // initialisation of position, momentum and path length
  x = fts.position();
  p = fts.momentum();
  s = 0;
  // (transverse) curvature
  double rho = fts.transverseCurvature();
  //
  // Straight line approximation? |rho|<1.e-10 equivalent to ~ 1um 
  // difference in transversal position at 10m.
  //
  if( fabs(rho)<1.e-10 )
    return propagateWithLineCrossing(fts.position(),p,plane,x,s);
  //
  // Helix case 
  //
  GlobalVector u = plane.normalVector();
  const double small = 1.e-6; // for orientation of planes
  //
  // Frame-independant point and vector are created explicitely to 
  // avoid confusing gcc (refuses to compile with temporary objects
  // in the constructor).
  //
  HelixPlaneCrossing::PositionType helixPos(x);
  HelixPlaneCrossing::DirectionType helixDir(p);
  if (isOldPropagationType && fabs(u.z()) < small) {
    // barrel plane:
    // instantiate HelixBarrelPlaneCrossing, get vector of solutions and check for existance
    HelixBarrelPlaneCrossingByCircle planeCrossing(helixPos,helixDir,rho,propagationDirection());
    return propagateWithHelixCrossing(planeCrossing,plane,fts.momentum().mag(),x,p,s);
  }
  if (isOldPropagationType && fabs(u.x()) < small && fabs(u.y()) < small) {
    // forward plane:
    // instantiate HelixForwardPlaneCrossing, get vector of solutions and check for existance
    HelixForwardPlaneCrossing planeCrossing(helixPos,helixDir,rho,propagationDirection());
    return propagateWithHelixCrossing(planeCrossing,plane,fts.momentum().mag(),x,p,s);
  }
  else {
    // arbitrary plane:
    // instantiate HelixArbitraryPlaneCrossing, get vector of solutions and check for existance
    if(isOldPropagationType){
      HelixArbitraryPlaneCrossing planeCrossing(helixPos,helixDir,rho,propagationDirection());
      return propagateWithHelixCrossing(planeCrossing,plane,fts.momentum().mag(),x,p,s);
    }else{
      //--- Alternative implementation to be used for the propagation of the parameters  of looping
      //    particles that cross twice the (infinite) surface of the plane. It is not trivial to determine
      //    which of the two intersections has to be returned.

      //---- FIXME: WHAT FOLLOWS HAS TO BE REWRITTEN IN A CLEANER (AND CPU-OPTIMIZED) WAY ---------
      LogDebug("AnalyticalPropagator") << "In AnaliticalProp, calling HAPC " << "\n"
                       << "plane is centered in xyz: " 
                       << plane.position().x() << " , "
                       << plane.position().y() << " , " 
                       << plane.position().z() << "\n";


      GlobalPoint gp1 = fts.position();
      GlobalVector gm1 = fts.momentum();
      double s1 = 0;
      double rho1 = fts.transverseCurvature();
      HelixPlaneCrossing::PositionType helixPos1(gp1);
      HelixPlaneCrossing::DirectionType helixDir1(gm1);
      LogDebug("AnalyticalPropagator") << "gp1 before calling planeCrossing1: " << gp1 << "\n";
      HelixArbitraryPlaneCrossing planeCrossing1(helixPos1,helixDir1,rho1,propagationDirection());
      
      HelixPlaneCrossing::PositionType xGen;
      HelixPlaneCrossing::DirectionType pGen;
      
      double tolerance(0.0050);
      if(propagationDirection()==oppositeToMomentum)
    tolerance *=-1;

      bool check1 = propagateWithHelixCrossing(planeCrossing1,plane,fts.momentum().mag(),gp1,gm1,s1);
      double dphi1 = fabs(fts.momentum().phi()-gm1.phi());
      LogDebug("AnalyticalPropagator") << "check1, s1, dphi, gp1: " 
                       << check1 << " , "
                       << s1 << " , " 
                       << dphi1 << " , "
                       << gp1 << "\n";

      //move forward a bit to avoid that the propagator doesn't propagate because the state is already on surface.
      //we want to go to the other point of intersection between the helix and the plane
      xGen = planeCrossing1.position(s1+tolerance);
      pGen = planeCrossing1.direction(s1+tolerance);
      
      /*
      if(!check1 || s1>170 ){
    //PropagationDirection newDir = (propagationDirection() == alongMomentum) ? oppositeToMomentum : alongMomentum;
    PropagationDirection newDir = anyDirection;
    HelixArbitraryPlaneCrossing  planeCrossing1B(helixPos1,helixDir1,rho1,newDir);
    check1 = propagateWithHelixCrossing(planeCrossing1B,plane,fts.momentum().mag(),gp1,gm1,s1);
    LogDebug("AnalyticalPropagator") << "after second attempt, check1, s1,gp1: "
                     << check1 << " , "
                     << s1 << " , " << gp1 << "\n";

    xGen = planeCrossing1B.position(s1+tolerance);
    pGen = planeCrossing1B.direction(s1+tolerance);
      }
      */

      if(!check1){
    LogDebug("AnalyticalPropagator") << "failed also second attempt. No idea what to do, then bailout" << "\n";
      }

     
      pGen *= gm1.mag()/pGen.mag();
      GlobalPoint gp2(xGen);
      GlobalVector gm2(pGen);
      double s2 = 0;
      double rho2 = rho1;
      HelixPlaneCrossing::PositionType helixPos2(gp2);
      HelixPlaneCrossing::DirectionType helixDir2(gm2);
      HelixArbitraryPlaneCrossing planeCrossing2(helixPos2,helixDir2,rho2,propagationDirection());
      
      bool check2 = propagateWithHelixCrossing(planeCrossing2,plane,gm2.mag(),gp2,gm2,s2);
      
      if(!check2){
    x = gp1;
    p = gm1;
    s = s1;
    return check1;
      }
      
      if(!check1){
    edm::LogError("AnalyticalPropagator") << "LOGIC ERROR: I should not have entered here!" << "\n";
    return false;
      }


      LogDebug("AnalyticalPropagator")  << "check2, s2, gp2: " 
                    << check2 << " , "
                    << s2 << " , " << gp2 << "\n";
      

      double dist1 = (plane.position()-gp1).perp();
      double dist2 = (plane.position()-gp2).perp();


      LogDebug("AnalyticalPropagator") << "propDir, dist1, dist2: " 
                       << propagationDirection() << " , "
                       << dist1 << " , " 
                       << dist2 << "\n";
      
      //If there are two solutions, the one which is the closest to the module's center is chosen
      if(dist1<2*dist2){
    x = gp1;
    p = gm1;
    s = s1;
    return check1;
      }else if(dist2<2*dist1){
    x = gp2;
    p = gm2;
    s = s1+s2+tolerance;
    return check2;
      }else{
    if(fabs(s1)<fabs(s2)){
      x = gp1;
      p = gm1;
      s = s1;
      return check1;
    }else{
      x = gp2;
      p = gm2;
      s = s1+s2+tolerance;
      return check2;
    }   
      }
      
      //-------- END of ugly piece of code  ---------------
    }

  }
}

bool
AnalyticalPropagator::propagateWithLineCrossing (const GlobalPoint& x0, 
                         const GlobalVector& p0,
                         const Plane& plane,
                         GlobalPoint& x, double& s) const {
  //
  // Instantiate auxiliary object for finding intersection.
  // Frame-independant point and vector are created explicitely to 
  // avoid confusing gcc (refuses to compile with temporary objects
  // in the constructor).
  //
  StraightLinePlaneCrossing::PositionType pos(x0);
  StraightLinePlaneCrossing::DirectionType dir(p0);
  StraightLinePlaneCrossing planeCrossing(pos,dir,propagationDirection());
  //
  // get solution
  //
  std::pair<bool,double> propResult = planeCrossing.pathLength(plane);
  if ( !propResult.first )  return false;
  s = propResult.second;
  // point (reconverted to GlobalPoint)
  x = GlobalPoint(planeCrossing.position(s));
  //
  return true;
}

bool
AnalyticalPropagator::propagateWithLineCrossing (const GlobalPoint& x0, 
                         const GlobalVector& p0,
                         const Cylinder& cylinder,
                         GlobalPoint& x, double& s) const {
  //
  // Instantiate auxiliary object for finding intersection.
  // Frame-independant point and vector are created explicitely to 
  // avoid confusing gcc (refuses to compile with temporary objects
  // in the constructor).
  //
  StraightLineBarrelCylinderCrossing cylCrossing(x0,p0,propagationDirection());
  //
  // get solution
  //
  std::pair<bool,double> propResult = cylCrossing.pathLength(cylinder);
  if ( !propResult.first )  return false;
  s = propResult.second;
  // point (reconverted to GlobalPoint)
  x = cylCrossing.position(s);
  //
  return true;
}

bool
AnalyticalPropagator::propagateWithHelixCrossing (HelixPlaneCrossing& planeCrossing,
                          const Plane& plane,
                          const float pmag,
                          GlobalPoint& x,
                          GlobalVector& p,
                          double& s) const {
  // get solution
  std::pair<bool,double> propResult = planeCrossing.pathLength(plane);
  if ( !propResult.first )  return false;
  s = propResult.second;
  // point (reconverted to GlobalPoint)
  HelixPlaneCrossing::PositionType xGen = planeCrossing.position(s);
  x = GlobalPoint(xGen);
  // direction (reconverted to GlobalVector, renormalised)
  HelixPlaneCrossing::DirectionType pGen = planeCrossing.direction(s);
  pGen *= pmag/pGen.mag();
  p = GlobalVector(pGen);
  //
  return true;
}