class THaSpectrometer: public THaApparatus, public THaTrackingModule, public THaVertexModule

 Destructor. Delete the lists of specialized detectors.
 FIXME: delete tracks, pid, vertices too?

 Add a detector to the internal lists of spectrometer detectors.
 This method is useful for quick testing of a new detector class that
 one doesn't want to include permanently in an Apparatus yet.
 The detector object must be allocated and deleted by the caller.
 Duplicate detector names are not allowed.

 Add a particle type to the list of particles for which we want PID.
 The "charge" argument is optional.

 Combine the PID information from all detectors into an overall PID
 for each track.  The actual work is done in the THaPIDinfo class.
 This is just a loop over all tracks.
 Called by Reconstruct().

 Clear the spectrometer data for next event.

 Define the default set of PID particles:
  pion, kaon, proton

 Define/delete standard variables for a spectrometer (tracks etc.)
 Can be overridden or extended by derived (actual) apparatuses

 Return vertex vector of the Golden Track.
 Overrides standard method of THaVertexModule.

 Initialize lists of specialized detectors.
 Private function called by Reconstruct().

 Coarse Tracking: First step of spectrometer analysis

 2nd step: Coarse processing.  Pass the coarse tracks to the remaining
 detectors for any processing that can be done at this stage.
 This may include clustering and preliminary PID.
 PID information is tacked onto the tracks as a THaPIDinfo object.

 Fine tracking.  Compute the tracks with high precision.
 If coarse tracking was done, this step should simply "refine" the
 tracks found earlier, not add new tracks to fTrack.

 This method implements a fairly generic algorithm for spectrometer
 reconstruction which should be useful for most situations.
 Additional, equipment-specific processing can be done in
 a derived class that calls this method first.

 The algorithm is as follows:

 For all tracking detectors:
   CoarseTrack()
 For all non-tracking detectors:
   CoarseProcess()
 For all tracking detectors:
   FineTrack()
 Reconstruct tracks to target
 For all non-tracking detectors:
   FineProcess()
 Compute additional attributes of tracks (e.g. momentum, beta)
 Find "Golden Track"
 Combine all PID detectors to get overall PID for each track

 Convert TRANSPORT coordinates of 'track' to momentum vector 'pvect'
 in the lab coordinate system (z = beam, y = up).
 Uses the spectrometer angles from the database (loaded during Init())
 for the transformation.

 The track origin (vertex) is not calculated here because
 doing so requires knowledge of beam positions and and angles.
 Vertex calculations are done in a separate physics module.

 Convert TRANSPORT vector to lab vector.
 Inputs:
  p:  TRANSPORT momentum (absolute)
  th: Tangent of TRANSPORT theta
  ph: Tangent of TRANSPORT phi
 Output:
  pvect: Vector in lab frame (z = beam, y = up) in same units as p.

 Note: Simple vector transformation can be done trivially by multiplying
 with the appropriate rotation matrix, e.g.:
  TVector3 lab_vector = spect->GetToLabRot() * transport_vector;

 Convert lab coordinates to TRANSPORT coordinates in the spectrometer
 coordinate system.
 Inputs:
  vertex:  Reaction point in lab system
  pvect:   Momentum vector in lab
 Outputs:
  tvertex: The vertex point in the TRANSPORT system, without any
           coordinate projections applied
  ray:     The TRANSPORT ray according to TRANSPORT conventions.
           This is an array of size 6 with elements x, tan(theta),
           y, tan(y), z, and delta.
           z is set to 0, and accordingly x and y are the TRANSPORT
           coordinates in the z=0 plane. delta is computed with respect
           to the present spectrometer's central momentum.
           Units are the same as of the input vectors.

 Query the run database for parameters specific to this spectrometer
 (central angles, momentum, offsets, drift, etc.)

inlines

 The following is specific to small-acceptance pointing spectrometers
 using spectrometer-specific coordinates such as TRANSPORT