TrajectoryStateAccessor Class Reference

#include <TrajectoryStateAccessor.h>

Public Member Functions
float	inversePtError () const
	TrajectoryStateAccessor (const FreeTrajectoryState &fts)

Private Attributes
const FreeTrajectoryState &	theFts

Detailed Description

Helper class to obtain the uncertainty on specific trajectory parameters.

Definition at line 10 of file TrajectoryStateAccessor.h.

Constructor & Destructor Documentation

TrajectoryStateAccessor::TrajectoryStateAccessor ( const FreeTrajectoryState &  fts )

inline

Definition at line 13 of file TrajectoryStateAccessor.h.

                                                           :
    theFts(fts) {}

Member Function Documentation

float TrajectoryStateAccessor::inversePtError

(

)

const

Definition at line 5 of file TrajectoryStateAccessor.cc.

References corr, FreeTrajectoryState::curvilinearError(), CurvilinearTrajectoryError::matrix(), FreeTrajectoryState::momentum(), PV3DBase< T, PVType, FrameType >::perp2(), mathSSE::sqrt(), theFts, and PV3DBase< T, PVType, FrameType >::z().

Referenced by MinPtTrajectoryFilter::test(), and ThresholdPtTrajectoryFilter::test().

{
  GlobalVector momentum = theFts.momentum();
  AlgebraicSymMatrix55 const & errMatrix = theFts.curvilinearError().matrix();
  
  float ptRec2= momentum.perp2();
  float pzRec = momentum.z();
  float pzRec2 = pzRec*pzRec;
  float CosTheta2 = (pzRec2)/(ptRec2+pzRec2);
  float SinTheta2 = 1.f-CosTheta2;
 
  float par2 = CosTheta2/ptRec2;

  float InvpErr=errMatrix(0,0);
  float thetaErr=errMatrix(1,1);
  float corr=errMatrix(0,1);

  float invPtErr2 =
    ( InvpErr + par2*thetaErr - 
      2.f*std::sqrt(par2)*corr
    )/(SinTheta2);
  return std::sqrt(invPtErr2);
}

Member Data Documentation

const FreeTrajectoryState& TrajectoryStateAccessor::theFts

private

Definition at line 20 of file TrajectoryStateAccessor.h.

Referenced by inversePtError().