#include <HelixForwardPlaneCrossing.h>

Inheritance diagram for HelixForwardPlaneCrossing:

Public Member Functions
virtual DirectionType	direction (double s) const

	HelixForwardPlaneCrossing (const PositionType &point, const DirectionType &direction, const float curvature, const PropagationDirection propDir=alongMomentum)

virtual std::pair< bool, double >	pathLength (const Plane &plane)

virtual PositionType	position (double s) const

virtual	~HelixForwardPlaneCrossing ()

Private Types
typedef Basic3DVector< double >	DirectionTypeDouble

typedef Basic3DVector< double >	PositionTypeDouble

Private Attributes
double	theCachedCDPhi

double	theCachedDPhi

double	theCachedS

double	theCachedSDPhi

double	theCosPhi0

double	theCosTheta

const PropagationDirection	thePropDir

const double	theRho

double	theSinPhi0

double	theSinTheta

const double	theX0

const double	theY0

const double	theZ0

Static Private Attributes
static const float	theNumericalPrecision = 5.e-7

Additional Inherited Members
Public Types inherited from HelixPlaneCrossing
typedef Basic3DVector< float >	DirectionType

typedef Basic3DVector< float >	PositionType
	the helix is passed to the constructor and does not appear in the interface More...

Detailed Description

Calculates intersections of a helix with planes perpendicular to the z-axis.

Definition at line 10 of file HelixForwardPlaneCrossing.h.

Member Typedef Documentation

typedef Basic3DVector<double> HelixForwardPlaneCrossing::DirectionTypeDouble

private

Definition at line 39 of file HelixForwardPlaneCrossing.h.

typedef Basic3DVector<double> HelixForwardPlaneCrossing::PositionTypeDouble

private

Definition at line 38 of file HelixForwardPlaneCrossing.h.

Constructor & Destructor Documentation

HelixForwardPlaneCrossing::HelixForwardPlaneCrossing	(	const PositionType &	point,
		const DirectionType &	direction,
		const float	curvature,
		const PropagationDirection	propDir = `alongMomentum`
	)

Constructor using point, direction and (transverse!) curvature.

Definition at line 7 of file HelixForwardPlaneCrossing.cc.

References p2, mathSSE::sqrt(), theCosPhi0, theCosTheta, theSinPhi0, theSinTheta, Basic3DVector< T >::x(), Basic3DVector< T >::y(), and Basic3DVector< T >::z().

                                                                  :
   theX0(point.x()),
   theY0(point.y()),
   theZ0(point.z()),
   theRho(curvature),
   thePropDir(propDir),
   theCachedS(0),
   theCachedDPhi(0.),
   theCachedSDPhi(0.),
   theCachedCDPhi(1.)
 {
   //
   // Components of direction vector (with correct normalisation)
   //
   double px = direction.x();
   double py = direction.y();
   double pz = direction.z();
   double pt2 = px*px+py*py;
   double p2 = pt2+pz*pz;
   double pI = 1./sqrt(p2);
   double ptI = 1./sqrt(pt2);
   theCosPhi0 = px*ptI;
   theSinPhi0 = py*ptI;
   theCosTheta = pz*pI;
   theSinTheta = pt2*ptI*pI;
 
 }

virtual HelixForwardPlaneCrossing::~HelixForwardPlaneCrossing ( )

inlinevirtual

Definition at line 19 of file HelixForwardPlaneCrossing.h.

19 {}

Member Function Documentation

HelixPlaneCrossing::DirectionType HelixForwardPlaneCrossing::direction ( double s ) const

virtual

Direction at pathlength s from the starting point.

Implements HelixPlaneCrossing.

Definition at line 94 of file HelixForwardPlaneCrossing.cc.

References funct::cos(), alignCSCRings::e, alignCSCRings::s, funct::sin(), theCachedCDPhi, theCachedDPhi, theCachedS, theCachedSDPhi, theCosPhi0, theCosTheta, theRho, theSinPhi0, and theSinTheta.

                                                     {
   //
   // Calculate delta phi (if not already available)
   //
   if ( s!=theCachedS ) {
     theCachedS = s;
     theCachedDPhi = theCachedS*theRho*theSinTheta;
     theCachedSDPhi = sin(theCachedDPhi);
     theCachedCDPhi = cos(theCachedDPhi);
   }
 
   if ( fabs(theCachedDPhi)>1.e-4 ) {
     // full helix formula
     return DirectionType(theCosPhi0*theCachedCDPhi-theSinPhi0*theCachedSDPhi,
              theSinPhi0*theCachedCDPhi+theCosPhi0*theCachedSDPhi,
              theCosTheta/theSinTheta);
   }
   else {
     // 2nd order
     double dph = theCachedS*theRho*theSinTheta;
     return DirectionType(theCosPhi0-(theSinPhi0+0.5*theCosPhi0*dph)*dph,
              theSinPhi0+(theCosPhi0-0.5*theSinPhi0*dph)*dph,
              theCosTheta/theSinTheta);
   }
 }

std::pair< bool, double > HelixForwardPlaneCrossing::pathLength ( const Plane & plane )

virtual

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

Implements HelixPlaneCrossing.

Definition at line 41 of file HelixForwardPlaneCrossing.cc.

References abs, alongMomentum, oppositeToMomentum, GloballyPositioned< T >::position(), theCosTheta, thePropDir, theSinTheta, theZ0, and Basic3DVector< T >::z().

                                                         {
   //
   // Protect against p_z=0 and calculate path length
   //
   if ( std::abs(theCosTheta/theSinTheta)<FLT_MIN )  return std::pair<bool,double>(false,0);
 
   double dS = (plane.position().z()-theZ0) / theCosTheta;
 
   if ( (thePropDir==alongMomentum && dS<0.) ||
        (thePropDir==oppositeToMomentum && dS>0.) )  return std::pair<bool,double>(false,0);
   //
   // Return result
   //
   return std::pair<bool,double>(true,dS);
 }

HelixPlaneCrossing::PositionType HelixForwardPlaneCrossing::position ( double s ) const

virtual

Position at pathlength s from the starting point.

Implements HelixPlaneCrossing.

Definition at line 60 of file HelixForwardPlaneCrossing.cc.

References abs, funct::cos(), alignCSCRings::e, python.connectstrParser::o, alignCSCRings::s, funct::sin(), theCachedCDPhi, theCachedDPhi, theCachedS, theCachedSDPhi, theCosPhi0, theCosTheta, theRho, theSinPhi0, theSinTheta, theX0, theY0, and theZ0.

                                                    {
   //
   // Calculate delta phi (if not already available)
   //
   if ( s!=theCachedS ) {
     theCachedS = s;
     theCachedDPhi = theCachedS*theRho*theSinTheta;
     theCachedSDPhi = sin(theCachedDPhi);
     theCachedCDPhi = cos(theCachedDPhi);
   }
   //
   // Calculate with appropriate formulation of full helix formula or with 
   //   2nd order approximation.
   //
   if ( std::abs(theCachedDPhi)>1.e-4 ) {
     // "standard" helix formula
     // "standard" helix formula
     double o = 1./theRho;
     return PositionTypeDouble(theX0+(-theSinPhi0*(1.-theCachedCDPhi)+theCosPhi0*theCachedSDPhi)*o,
                   theY0+( theCosPhi0*(1.-theCachedCDPhi)+theSinPhi0*theCachedSDPhi)*o,
                   theZ0+theCachedS*theCosTheta);
   }
   else {
     // 2nd order
     double st = theCachedS*theSinTheta;
     return PositionType(theX0+(theCosPhi0-st*0.5*theRho*theSinPhi0)*st,
             theY0+(theSinPhi0+st*0.5*theRho*theCosPhi0)*st,
             theZ0+st*theCosTheta/theSinTheta);
   }
 }