#include <StraightLineBarrelCylinderCrossing.h>

Public Member Functions
std::pair< bool, double >	pathLength (const Cylinder &cyl) const

GlobalPoint	position (const double s) const

	StraightLineBarrelCylinderCrossing (const GlobalPoint &startingPos, const GlobalVector &startingDir, const PropagationDirection propDir)

Private Types
typedef GlobalVector	DirectionType

typedef Basic2DVector< float >	DirectionType2D

typedef GlobalPoint	PositionType

typedef Basic2DVector< float >	PositionType2D

Private Member Functions
std::pair< bool, double >	chooseSolution (const double s1, const double s2) const
	Chooses the right solution w.r.t. the propagation direction. More...

Private Attributes
const DirectionType	theP0

const PropagationDirection	thePropDir

const PositionType	theX0

Detailed Description

Calculates the intersection of a straight line with a barrel cylinder.

Definition at line 17 of file StraightLineBarrelCylinderCrossing.h.

Member Typedef Documentation

◆ DirectionType

typedef GlobalVector StraightLineBarrelCylinderCrossing::DirectionType

private

Definition at line 47 of file StraightLineBarrelCylinderCrossing.h.

◆ DirectionType2D

typedef Basic2DVector<float> StraightLineBarrelCylinderCrossing::DirectionType2D

private

Definition at line 49 of file StraightLineBarrelCylinderCrossing.h.

◆ PositionType

typedef GlobalPoint StraightLineBarrelCylinderCrossing::PositionType

private

Definition at line 46 of file StraightLineBarrelCylinderCrossing.h.

◆ PositionType2D

typedef Basic2DVector<float> StraightLineBarrelCylinderCrossing::PositionType2D

private

Definition at line 48 of file StraightLineBarrelCylinderCrossing.h.

Constructor & Destructor Documentation

◆ StraightLineBarrelCylinderCrossing()

StraightLineBarrelCylinderCrossing::StraightLineBarrelCylinderCrossing	(	const GlobalPoint &	startingPos,
		const GlobalVector &	startingDir,
		const PropagationDirection	propDir
	)

Constructor uses global frame (barrel cylinders are by definition in global co-ordinates)

Definition at line 7 of file StraightLineBarrelCylinderCrossing.cc.

10 : theX0(startingPos), theP0(startingDir.unit()), thePropDir(propDir) {}

Member Function Documentation

◆ chooseSolution()

std::pair< bool, double > StraightLineBarrelCylinderCrossing::chooseSolution	(	const double	s1,
		const double	s2
	)		const

private

Chooses the right solution w.r.t. the propagation direction.

Definition at line 35 of file StraightLineBarrelCylinderCrossing.cc.

                                                                                                                {
   //
   // follows the logic implemented in HelixBarrelCylinderCrossing
   //
   if (thePropDir == anyDirection) {
     return std::pair<bool, double>(true, (fabs(s1) < fabs(s2) ? s1 : s2));
   } else {
     int propSign = thePropDir == alongMomentum ? 1 : -1;
     if (s1 * s2 < 0) {
       // if different signs return the positive one
       return std::pair<bool, double>(true, ((s1 * propSign > 0) ? s1 : s2));
     } else if (s1 * propSign > 0) {
       // if both positive, return the shortest
       return std::pair<bool, double>(true, (fabs(s1) < fabs(s2) ? s1 : s2));
     }
   }
   return std::pair<bool, double>(false, 0.);
 }

References alongMomentum, anyDirection, and thePropDir.

Referenced by pathLength().

◆ pathLength()

std::pair< bool, double > StraightLineBarrelCylinderCrossing::pathLength ( const Cylinder & cyl ) const

Propagation status (true if valid) and (signed) path length along the line from the starting point to the cylinder.

Definition at line 12 of file StraightLineBarrelCylinderCrossing.cc.

                                                                                                    {
   //
   // radius of cylinder and transversal position relative to axis
   //
   double R(cylinder.radius());
   GlobalPoint axis(cylinder.toGlobal(Cylinder::LocalPoint(0., 0.)));
   PositionType2D xt2d(theX0.x() - axis.x(), theX0.y() - axis.y());
   //
   // transverse direction
   //
   DirectionType2D pt2d(theP0.x(), theP0.y());
   //
   // solution of quadratic equation for s - assume |theP0|=1
   //
   RealQuadEquation eq(pt2d.mag2(), 2. * xt2d.dot(pt2d), xt2d.mag2() - R * R);
   if (!eq.hasSolution)
     return std::pair<bool, double>(false, 0.);
   //
   // choice of solution and verification of direction
   //
   return chooseSolution(eq.first, eq.second);
 }

References chooseSolution(), dttmaxenums::R, Cylinder::radius(), theP0, theX0, Surface::toGlobal(), PV3DBase< T, PVType, FrameType >::x(), and PV3DBase< T, PVType, FrameType >::y().

Referenced by RKPropagatorInS::propagateParametersOnCylinder().

◆ position()

GlobalPoint StraightLineBarrelCylinderCrossing::position ( const double s ) const

inline

Returns the position along the line that corresponds to path length "s" from the starting point. If s is obtained from the pathLength method the position is the intersection point with the cylinder.

Definition at line 36 of file StraightLineBarrelCylinderCrossing.h.

36 { return GlobalPoint(theX0 + s * theP0); }

References alignCSCRings::s, theP0, and theX0.

Referenced by RKPropagatorInS::propagateParametersOnCylinder().