#include <TwoTrackMinimumDistanceHelixHelix.h>

Public Member Functions
bool	calculate (const GlobalTrajectoryParameters &, const GlobalTrajectoryParameters &, const float qual=.001)
double	firstAngle () const
std::pair< double, double >	pathLength () const
std::pair< GlobalPoint, GlobalPoint >	points () const
double	secondAngle () const
	TwoTrackMinimumDistanceHelixHelix ()
	~TwoTrackMinimumDistanceHelixHelix ()
Private Member Functions
void	finalPoints () const
bool	oneIteration (double &, double &) const
bool	updateCoeffs (const GlobalPoint &, const GlobalPoint &)
Private Attributes
double	pathG
double	pathH
GlobalPoint	pointG
GlobalPoint	pointH
bool	pointsUpdated
double	thea
double	theb
double	thec1
double	thec2
double	thecospG
double	thecospG0
double	thecospH
double	thecospH0
double	thed1
double	thed2
double	thee1
double	thee2
double	theg
GlobalTrajectoryParameters const *	theG
GlobalTrajectoryParameters const *	theH
double	theh
int	themaxiter
double	themaxjump
double	thepG
double	thepG0
double	thepH
double	thepH0
double	thesingjacI
double	thesinpG
double	thesinpG0
double	thesinpH
double	thesinpH0
double	thetanlambdaG
double	thetanlambdaH

Detailed Description

This is a helper class for TwoTrackMinimumDistance. No user should need direct access to this class. It actually implements a Newton-Kantorowitsch method for finding the minimum distance between two tracks.

Definition at line 18 of file TwoTrackMinimumDistanceHelixHelix.h.

Constructor & Destructor Documentation

TwoTrackMinimumDistanceHelixHelix::TwoTrackMinimumDistanceHelixHelix ( )

Definition at line 33 of file TwoTrackMinimumDistanceHelixHelix.cc.

                                                                    :
theH(0), theG(0), pointsUpdated(false), themaxjump(20),thesingjacI(1./0.1), themaxiter(4)
{ }

TwoTrackMinimumDistanceHelixHelix::~TwoTrackMinimumDistanceHelixHelix ( )

Definition at line 37 of file TwoTrackMinimumDistanceHelixHelix.cc.

{}

Member Function Documentation

bool TwoTrackMinimumDistanceHelixHelix::calculate	(	const GlobalTrajectoryParameters &	G,
		const GlobalTrajectoryParameters &	H,
		const float	qual = `.001`
	)

Definition at line 142 of file TwoTrackMinimumDistanceHelixHelix.cc.

References oneIteration(), pointsUpdated, GlobalTrajectoryParameters::position(), theG, theg, theH, theh, themaxiter, themaxjump, thepG, thepG0, thepH, thepH0, and updateCoeffs().

                                                                                                           {
  pointsUpdated = false;
  theG= &G;
  theH= &H;
  bool retval=false;
  
  if ( updateCoeffs ( theG->position(), theH->position() ) ) return true;
  
  thepG = thepG0;
  thepH = thepH0;
  
  int counter=0;
  double pH=0; double pG=0;
  do {
    retval=oneIteration ( pG, pH );
    if ( std::isinf(pG) || std::isinf(pH) ) retval=true;
    if ( counter++>themaxiter ) retval=true;
  } while ( (!retval) && ( fabs(pG) > qual || fabs(pH) > qual ));
  if ( fabs ( theg * ( thepG - thepG0 ) ) > themaxjump ) retval=true;
  if ( fabs ( theh * ( thepH - thepH0 ) ) > themaxjump ) retval=true;
  return retval;
}

void TwoTrackMinimumDistanceHelixHelix::finalPoints ( ) const [private]

Definition at line 168 of file TwoTrackMinimumDistanceHelixHelix.cc.

References funct::cos(), pathG, pathH, pointG, pointH, pointsUpdated, GlobalTrajectoryParameters::position(), funct::sin(), mathSSE::sqrt(), thecospG0, thecospH0, theG, theg, theH, theh, thepG, thepG0, thepH, thepH0, thesinpG0, thesinpH0, thetanlambdaG, and thetanlambdaH.

Referenced by pathLength(), and points().

                                                          {
  GlobalVector tmpG( sin(thepG) - thesinpG0,
                   - cos(thepG) + thecospG0,
                   thetanlambdaG * ( thepG- thepG0 ) 
                   );
  pointG = theG->position() + theg * tmpG;
  pathG = ( thepG- thepG0 ) * (theg*sqrt(1+thetanlambdaG*thetanlambdaG)) ;

  GlobalVector tmpH( sin(thepH) - thesinpH0,
                   - cos(thepH) + thecospH0,
                   thetanlambdaH * ( thepH- thepH0 ) 
                   );
  pointH = theH->position() + theh * tmpH;
  pathH = ( thepH- thepH0 ) * (theh*sqrt(1+thetanlambdaH*thetanlambdaH)) ;

  pointsUpdated = true;
}

double TwoTrackMinimumDistanceHelixHelix::firstAngle ( ) const [inline]

Definition at line 40 of file TwoTrackMinimumDistanceHelixHelix.h.

References thepG.

{return thepG;}

bool TwoTrackMinimumDistanceHelixHelix::oneIteration	(	double &	dH,
		double &	dG
	)		const `[private]`

Definition at line 101 of file TwoTrackMinimumDistanceHelixHelix.cc.

References funct::cos(), funct::sin(), thea, theb, thec1, thec2, thecospG, thecospH, thed1, thed2, thee1, thee2, theg, theh, thepG, thepH, thesingjacI, thesinpG, and thesinpH.

Referenced by calculate().

                                                                                    {
  thesinpH=sin(thepH);
  thecospH=cos(thepH);
  thesinpG=sin(thepG);
  thecospG=cos(thepG);
  
  const double A11= theh * ( - thesinpH * ( thea - theg * thesinpG ) +
                             thecospH * ( theb + theg * thecospG ) + thec1);
  if (A11 < 0) { return true; };
  const double A22= -theg * (- thesinpG * ( thea + theh * thesinpH ) +
                             thecospG*( theb - theh * thecospH ) + thec2);
  if (A22 < 0) { return true; };
  const double A12= theh * (-theg * thecospG * thecospH -
                            theg * thesinpH * thesinpG + thed1);
  const double A21= -theg * (theh * thecospG * thecospH +
                             theh * thesinpH * thesinpG + thed2);
  const double detaI = 1./(A11 * A22 - A12 * A21);
  const double z1=theh * ( thecospH * ( thea - theg * thesinpG ) + thesinpH *
                           ( theb + theg*thecospG ) + thec1 * thepH + thed1 * thepG + thee1);
  const double z2=-theg * (thecospG * ( thea + theh * thesinpH ) + thesinpG *
                           ( theb - theh*thecospH ) + thec2 * thepG + thed2 * thepH + thee2);
  
  dH=( z1 * A22 - z2 * A12 ) * detaI;
  dG=( z2 * A11 - z1 * A21 ) * detaI;
  if ( fabs(detaI) > thesingjacI ) { return true; };
  
  thepH -= dH;
  thepG -= dG;
  return false;
}

std::pair<double, double> TwoTrackMinimumDistanceHelixHelix::pathLength ( ) const [inline]

Definition at line 33 of file TwoTrackMinimumDistanceHelixHelix.h.

References finalPoints(), pathG, pathH, and pointsUpdated.

                                              {
    if (!pointsUpdated) finalPoints();
    return std::pair <double, double> ( pathG, pathH);
  }

std::pair<GlobalPoint, GlobalPoint> TwoTrackMinimumDistanceHelixHelix::points ( ) const [inline]

Definition at line 28 of file TwoTrackMinimumDistanceHelixHelix.h.

References finalPoints(), pointG, pointH, and pointsUpdated.

                                                    {
    if (!pointsUpdated) finalPoints();
    return std::pair<GlobalPoint, GlobalPoint> (pointG, pointH);
  }

double TwoTrackMinimumDistanceHelixHelix::secondAngle ( ) const [inline]

Definition at line 41 of file TwoTrackMinimumDistanceHelixHelix.h.

References thepH.

{return thepH;}

bool TwoTrackMinimumDistanceHelixHelix::updateCoeffs	(	const GlobalPoint &	gpH,
		const GlobalPoint &	gpG
	)		`[private]`

Definition at line 39 of file TwoTrackMinimumDistanceHelixHelix.cc.

References GlobalTrajectoryParameters::charge(), ora::Gt, MagneticField::inInverseGeV(), GlobalTrajectoryParameters::magneticField(), GlobalTrajectoryParameters::momentum(), PV3DBase< T, PVType, FrameType >::perp(), GlobalTrajectoryParameters::position(), thea, theb, thec1, thec2, thecospG0, thecospH0, thed1, thed2, thee1, thee2, theG, theg, theH, theh, thepG0, thepH0, thesinpG0, thesinpH0, thetanlambdaG, thetanlambdaH, PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), and PV3DBase< T, PVType, FrameType >::z().

Referenced by calculate().

                                                       {

  const double Bc2kH = theH->magneticField().inInverseGeV(gpH).z();
  const double Bc2kG = theG->magneticField().inInverseGeV(gpG).z();
  const double Ht= theH->momentum().perp();
  const double Gt= theG->momentum().perp();
  //  thelambdaH=asin ( theH->momentum().z() / Hn );
  
  if ( Ht == 0. || Gt == 0. ) {
    edm::LogWarning ("TwoTrackMinimumDistanceHelixHelix")
      << "transverse momentum of input trajectory is zero.";
    return true;
  };
  
  if ( theH->charge() == 0. || theG->charge() == 0. ) {
    edm::LogWarning ("TwoTrackMinimumDistanceHelixHelix")
      << "charge of input track is zero.";
    return true;
  };
  
  if ( Bc2kG == 0.) {
    edm::LogWarning ("TwoTrackMinimumDistanceHelixHelix")
      << "magnetic field at point " << gpG << " is zero.";
    return true;
  };
  
  if ( Bc2kH == 0. ) {
    edm::LogWarning ("TwoTrackMinimumDistanceHelixHelix")
      << "magnetic field at point " << gpH << " is zero.";
    return true;
  };
  
  theh= Ht / (theH->charge() * Bc2kH );
  thesinpH0= - theH->momentum().y() / ( Ht );
  thecospH0= - theH->momentum().x() / ( Ht );
  thetanlambdaH = - theH->momentum().z() / ( Ht);
  thepH0 = atan2 ( thesinpH0 , thecospH0 );
  
  // thelambdaG=asin ( theG->momentum().z()/( Gn ) );
  
  theg= Gt / (theG->charge() * Bc2kG );
  thesinpG0= - theG->momentum().y() / ( Gt);
  thecospG0= - theG->momentum().x() / (Gt);
  thetanlambdaG = - theG->momentum().z() / ( Gt);
  thepG0 = atan2 ( thesinpG0 , thecospG0 );
  
  thea=theH->position().x() - theG->position().x() + theg * thesinpG0 -
    theh * thesinpH0;
  theb=theH->position().y() - theG->position().y() - theg * thecospG0 +
    theh * thecospH0;
  thec1=  theh * thetanlambdaH * thetanlambdaH;
  thec2= -theg * thetanlambdaG * thetanlambdaG;
  thed1= -theg * thetanlambdaG * thetanlambdaH;
  thed2=  theh * thetanlambdaG * thetanlambdaH;
  thee1= thetanlambdaH * ( theH->position().z() - theG->position().z() -
                           theh * thepH0 * thetanlambdaH + theg * thepG0 * thetanlambdaG );
  thee2= thetanlambdaG * ( theH->position().z() - theG->position().z() -
                           theh * thepH0 * thetanlambdaH + theg * thepG0 * thetanlambdaG );
  return false;
}