class HKalTrackState: public TObject

 Create state with dummy state vector and matrices.
 stateType: state is either for the prediction, filtering, smoothing or inverse filtering step in the Kalman filter
 measDim:  dimension of measurement vector
 stateDim: dimension of state vector.

 Create a state with dummy matrices and sets the state vector equal to function
 parameter sv.
 stateType: state is either for the prediction, filtering, smoothing or inverse filtering step in the Kalman filter
 sv:        state vector.
 measDim:   dimension of measurement vector.

 Calculates a direction unit vector from this state.
 dir: track direction (return value).

 Calculates a direction unit vector from a state vector given by function
 parameter sv.
 dir: track direction (return value)
 sv:  state vector to calculate direction from.

 Calculates the momentum vector from this state.
 dir: track momentum (return value).

 Calculates momentum vector from a state vector given by function
 parameter sv.
 dir: track momentum (return value)
 sv:  state vector to calculate direction from.

 Calculate the track position as a three dimensional vector from this state.
 Only two coordinates are stored in the state vector. The z-coordinate is
 calculated by going in z-direction and find the intersection with a plane.
 pos:   track position (return value).
 plane: the plane the track is on.

 Calculate the track position as a three dimensional vector from the state
 given by function parameter sv.
 Only two coordinates are stored in the state vector. The z-coordinate is
 calculated by going in z-direction and find the intersection with a plane.
 pos:   track position (return value).
 plane: the plane the track is on.

 Calculate the track position and direction as three dimensional vectors
 from this state.
 pos:   track position (return value)
 dir:   track direction (return value)
 plane: the plane the track is on

 Return the state vector from a position, direction and momentum.
 sv:  the state vector (return value)
 qp:  particle charage in elementary charges divided by magnitude of momentum in MeV/c
 pos: track position
 dir: track direction.

 Resets state vector to zeroes, matrices to unit matrix.

 Prints information about the state.
 opt: Determines what information about the object will be printed.
 Capitalization does not matter.
 If opt contains:
 "S": print state vector
 "F": print propagator matrix
 "C": print covariance matrix
 "H": print projector matrix
 "Q": print process noise matrix
 If opt is empty all of the above will be printed.

 Transform the state vector of this object using a rotation matrix.
 transMat: the rotation matrix
 plane:    the plane the track is on. Needed to calculate the z-coordinate of the
           track position.

 Transform a state vector given in virtual layer coordinates to sector coordinates.

 Output:
 svSec: Track state vector in sector coordinates.

 Input:
 svLay: Track state vector in virtual layer coordinates.
 plane: The plane defining the virtual layer system.

 State vector in sector coordinate system: (x,y,tx,ty,qp).
 State vector in layer  coordinate system: (u,v,tu,tv,qp).
 Layer coordinate system is defined by an origin vector O,
 two orthogonal Axis U and V on the layer and a normal vector W.
 All axis are given in sector coordinate system.

 Transformation from layer to sector:
 position in sector coordinates:
 P = O + u*U + v*V
 direction in sector coordinates:
 A = 1/sqrt(1 + tu^2 + tv^2) * (w + tu*U + tv*V)
 tx = A.x() / A.z()
 ty = A.y() / A.z()

 Transform a state vector given in virtual layer coordinates to sector coordinates.

 Output:
 svLay: Track state vector in virtual layer coordinates.

 Input:
 svSec: Track state vector in sector coordinates.
 plane: The plane defining the virtual layer system.

 State vector in sector coordinate system: (x,y,tx,ty,qp).
 State vector in layer  coordinate system: (u,v,tu,tv,qp).
 Layer coordinate system is defined by an origin vector O,
 two orthogonal Axis U and V on the layer and a normal vector W.
 All axis are given in sector coordinate system.

 Transformation from sector to layer:
 position on layer:
 u = (pos_sector - O) * U
 v = (pos_sector - O) * V
 direction on layer:
 tu = (A * U) / (A * W)
 tv = (A * V) / (A * W)
 with A = 1/sqrt(1 + tx^2 + ty^2) * (tx, ty, 1)^T the normalized direction vector in the sector coordinate system

 Replace the state's covariance matrix.

 Replace the state's propagator matrix.

 Replace the state's projector matrix.

 Replace the state's process noise matrix.

 Replace the state's track parameter vector.