trkf::KETrack Class Reference

#include <KETrack.h>

Inheritance diagram for trkf::KETrack:

Public Member Functions
	KETrack ()
	Default constructor. More...
	KETrack (const std::shared_ptr< const Surface > &psurf)
	Constructor - specify surface only. More...
	KETrack (const std::shared_ptr< const Surface > &psurf, const TrackVector &vec, const TrackError &err, Surface::TrackDirection dir=Surface::UNKNOWN, int pdg=0)
	Constructor - surface + track parameters + error matrix. More...
	KETrack (const KTrack &trk, const TrackError &err)
	Constructor - KTrack + error matrix. More...
virtual	~KETrack ()
	Destructor. More...
const TrackError &	getError () const
	Track error matrix. More...
double	PointingError () const
	Pointing error (radians). More...
TrackError &	getError ()
	Modifiable error matrix. More...
void	setError (const TrackError &err)
	Set error matrix. More...
std::optional< double >	combineTrack (const KETrack &tre)
	Combine two tracks. More...
virtual std::ostream &	Print (std::ostream &out, bool doTitle=true) const
	Printout. More...
Public Member Functions inherited from trkf::KTrack
	KTrack ()
	Enum. More...
	KTrack (const std::shared_ptr< const Surface > &psurf)
	Constructor - specify surface only. More...
	KTrack (std::shared_ptr< const Surface > psurf, const TrackVector &vec, Surface::TrackDirection dir=Surface::UNKNOWN, int pdg=0)
	Constructor - surface + track parameters. More...
virtual	~KTrack ()
	Destructor. More...
const std::shared_ptr< const Surface > &	getSurface () const
	Surface. More...
const TrackVector &	getVector () const
	Track state vector. More...
Surface::TrackDirection	getDirection () const
	Track direction. More...
int	PdgCode () const
	Pdg code. More...
double	Mass () const
	Based on pdg code. More...
TrackVector &	getVector ()
	Modifiable state vector. More...
void	setSurface (const std::shared_ptr< const Surface > &psurf)
	Set surface. More...
void	setVector (const TrackVector &vec)
	Set state vector. More...
void	setDirection (Surface::TrackDirection dir)
	Set direction. More...
void	setPdgCode (int pdg)
	Set pdg code. More...
bool	isValid () const
	Test if track is valid. More...
void	getPosition (double xyz[3]) const
	Get position of track. More...
void	getMomentum (double mom[3]) const
	Get momentum vector of track. More...
double	XLatitude () const
	Get x-latitude. More...
double	XLongitude () const
	Get x-longitude. More...

Private Attributes
TrackError	fErr
	Track error matrix. More...

Detailed Description

Definition at line 29 of file KETrack.h.

Constructor & Destructor Documentation

trkf::KETrack::KETrack

(

)

Default constructor.

Definition at line 18 of file KETrack.cxx.

{}

trkf::KETrack::KETrack

(

const std::shared_ptr< const Surface > &

psurf

)

Constructor - specify surface only.

Constructor - specify surface only.

Arguments:

psurf - Surface pointer.

Definition at line 26 of file KETrack.cxx.

: KTrack(psurf) {}

trkf::KETrack::KETrack	(	const std::shared_ptr< const Surface > &	psurf,
		const TrackVector &	vec,
		const TrackError &	err,
		Surface::TrackDirection	dir = Surface::UNKNOWN,
		int	pdg = 0
	)

Constructor - surface + track parameters + error matrix.

Constructor - surface + track parameters + error matrix.

Arguments:

psurf - Surface pointer. vec - Track state vector. err - Track error matrix. dir - Track direction. pdg - Pdg code.

Definition at line 38 of file KETrack.cxx.

    : KTrack(psurf, vec, dir, pdg), fErr(err)
  {}

trkf::KETrack::KETrack	(	const KTrack &	trk,
		const TrackError &	err
	)

Constructor - KTrack + error matrix.

Constructor - KTrack + error matrix.

Arguments:

trk - KTrack. err - Track error matrix.

Definition at line 53 of file KETrack.cxx.

: KTrack(trk), fErr(err) {}

trkf::KETrack::~KETrack ( )

virtual

Destructor.

Definition at line 56 of file KETrack.cxx.

{}

Member Function Documentation

std::optional< double > trkf::KETrack::combineTrack

(

const KETrack &

tre

)

Combine two tracks.

Combine two tracks.

Arguments:

tre - Another track.

Returns: Chisquare + success flag.

This method updates the current track to be the weighted average of itself and another track. The chisquare of the combination is returned as the result value. The combination can fail because the sum of the two error matrices is singular, in which case the success flag embedded in the return value is false.

Definition at line 89 of file KETrack.cxx.

  {
    // Make sure that the two track surfaces are the same.
    // Throw an exception if they are not.

    if (!getSurface()->isEqual(*tre.getSurface()))
      throw cet::exception("KETrack") << "Track combination surfaces are not the same.\n";

    // Default result is failure.

    std::optional<double> result{std::nullopt};

    // We will use asymmetric versions of the updating formulas, such
    // that the result is calculated as a perturbation on the
    // better-measured track.  We define the better measured track as
    // the one with the smaller error matrix trace.

    // Extract the two state vectors and error matrices as pointers.

    const TrackVector* vec1 = &getVector();
    const TrackError* err1 = &getError();
    const TrackVector* vec2 = &tre.getVector();
    const TrackError* err2 = &tre.getError();

    // Calculate the traces of the error matrices.

    double tr1 = 0;
    for (unsigned int i = 0; i < err1->size1(); ++i)
      tr1 += (*err1)(i, i);

    double tr2 = 0;
    for (unsigned int i = 0; i < err2->size1(); ++i)
      tr2 += (*err2)(i, i);

    // Define vec1, err1 as belong to the better measured track.
    // Swap if necessary.

    if (tr1 > tr2) {
      const TrackVector* tvec = vec1;
      vec1 = vec2;
      vec2 = tvec;
      const TrackError* terr = err1;
      err1 = err2;
      err2 = terr;
    }

    // Calculate the difference vector and difference error matrix.

    TrackVector dvec = *vec1 - *vec2;
    TrackError derr = *err1 + *err2;

    // Invert the difference error matrix.
    // This is the only place where a detectable failure can occur.

    bool ok = syminvert(derr);
    if (ok) {

      // Calculate updated state vector.
      // vec1 = vec1 - err1 * derr * dvec

      TrackVector tvec1 = prod(derr, dvec);
      TrackVector tvec2 = prod(*err1, tvec1);
      TrackVector tvec3 = *vec1 - tvec2;
      setVector(tvec3);

      // Calculate updated error matrix.
      // err1 = err1 - err1 * derr * err1

      TrackMatrix terr1 = prod(derr, *err1);
      TrackMatrix terr2 = prod(*err1, terr1);
      TrackError terr2s = ublas::symmetric_adaptor<TrackMatrix>(terr2);
      TrackError terr3 = *err1 - terr2s;
      setError(terr3);

      // Calculate chisquare.
      // chisq = dvec^T * derr * dvec

      TrackVector dvec1 = prod(derr, dvec);
      double chisq = inner_prod(dvec, dvec1);
      result = std::make_optional(chisq);
    }

    // Final validity check.

    if (!isValid()) result = std::nullopt;

    // Done.

    return result;
  }

const TrackError& trkf::KETrack::getError ( ) const

inline

Track error matrix.

Definition at line 53 of file KETrack.h.

TrackError& trkf::KETrack::getError ( )

inline

Modifiable error matrix.

Definition at line 62 of file KETrack.h.

double trkf::KETrack::PointingError

(

)

const

Pointing error (radians).

Calculate track pointing error (sigma, in radians).

This method calculates a single pointing error (sigma, in radians) based on the track parameters and error matrix. The actual calculation is done by the similarly names method of the surface class, since this class doesn't know what the track parameters mean.

Definition at line 67 of file KETrack.cxx.

  {
    if (!isValid())
      throw cet::exception("KETrack") << "Pointing error requested for invalid track.\n";
    return getSurface()->PointingError(getVector(), fErr);
  }

std::ostream & trkf::KETrack::Print ( std::ostream &  out, bool  doTitle = true  ) const

virtual

Printout.

Reimplemented from trkf::KTrack.

Reimplemented in trkf::KFitTrack, trkf::KHitsTrack, and trkf::KHitTrack.

Definition at line 182 of file KETrack.cxx.

  {
    if (doTitle) out << "KETrack:\n";

    // Print base class.

    KTrack::Print(out, false);

    // Print diagonal errors.

    out << "  Diagonal errors:\n"
        << "  [";
    for (unsigned int i = 0; i < fErr.size1(); ++i) {
      if (i != 0) out << ", ";
      double err = fErr(i, i);
      err = (err >= 0. ? std::sqrt(err) : -std::sqrt(-err));
      out << err;
    }
    out << "]\n";

    // Print correlations.

    out << "  Correlation matrix:";
    for (unsigned int i = 0; i < fErr.size1(); ++i) {
      if (i == 0)
        out << "\n  [";
      else
        out << "\n   ";
      for (unsigned int j = 0; j <= i; ++j) {
        if (j != 0) out << ", ";
        if (i == j)
          out << 1.;
        else {
          double eiijj = fErr(i, i) * fErr(j, j);
          double eij = fErr(i, j);
          if (eiijj != 0.)
            eij /= std::sqrt(std::abs(eiijj));
          else
            eij = 0.;
          out << eij;
        }
      }
    }
    out << "]\n";
    out << "  Pointing error = " << PointingError() << "\n";
    return out;
  }

void trkf::KETrack::setError ( const TrackError &  err )

inline

Set error matrix.

Definition at line 67 of file KETrack.h.

Member Data Documentation

TrackError trkf::KETrack::fErr

private

Track error matrix.

Definition at line 81 of file KETrack.h.

---

The documentation for this class was generated from the following files:

• KETrack.h
• KETrack.cxx