HelixExtrapolatorToLine2Order.h

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#ifndef HelixExtrapolatorToLine2Order_h_
#define HelixExtrapolatorToLine2Order_h_

#include "TrackingTools/GeomPropagators/interface/HelixLineExtrapolation.h"
#include "DataFormats/TrajectorySeed/interface/PropagationDirection.h"

class HelixExtrapolatorToLine2Order : public HelixLineExtrapolation {
public:
  HelixExtrapolatorToLine2Order(const PositionType& point,
                const DirectionType& direction,
                const float curvature,
                const PropagationDirection propDir = alongMomentum);

  HelixExtrapolatorToLine2Order(const double& x0, const double& y0, const double& z0,
                const double& cosPhi0, const double& sinPhi0,
                const double& cosTheta, const double& sinTheta,
                const double& rho,
                const PropagationDirection propDir = alongMomentum) :
    thePosition(x0,y0,z0),
    theDirection(cosPhi0,sinPhi0,cosTheta/sinTheta),
    theSinTheta(sinTheta),
    theRho(rho), 
    thePropDir(propDir) {}
  
  // destructor
  virtual ~HelixExtrapolatorToLine2Order() {}

  virtual std::pair<bool,double> pathLength (const GlobalPoint& point) const;

  virtual std::pair<bool,double> pathLength (const Line& line) const;

  virtual PositionType position(double s) const;

  virtual DirectionType direction(double s) const;

  PositionTypeDouble positionInDouble(double s) const;

  DirectionTypeDouble directionInDouble(double s) const;

private:
  virtual std::pair<bool,double> pathLengthFromCoefficients (const double ceq[4]) const;
  int solve3rdOrder (const double ceq[], double sol[]) const;
  int solve2ndOrder (const double ceq[], double sol[]) const;

private:
  const PositionTypeDouble thePosition;
  DirectionTypeDouble theDirection;
  double theSinTheta;
  const double theRho;
  const PropagationDirection thePropDir;
};

#endif