HTrack (LCSim 3.1.7 API)

java.lang.Object
- org.lcsim.recon.tracking.trffit.HTrack

```
public class HTrack
extends Object
```
This class describes a track as an ordered list of hits plus an ETrack (fitted vector and error matrix at a surface) and the fit chi-square.
Hits are ordered as they were fit.
The access to the list of hits is minimal. Users are expected to construct a new object to do more than update the fit or add a hit to the end of the list.
The method is_fit returns true if the track has been fit with all its hits. This state is set by calling set_fit and is unset when hits are added. No hits are required to be on the track (so one can store a fit without any hits).

Version:

1.0

Author:

Norman A. Graf

Field Summary

Fields
Modifier and Type Field and Description

protected double _chisq

protected List _hits

private int _nfit

protected ETrack _tre

Fields
Modifier and Type	Field and Description
`protected double`	`_chisq`
`protected List`	`_hits`
`private int`	`_nfit`
`protected ETrack`	`_tre`

Constructor Summary

Constructors
Constructor and Description
`HTrack()` Construct an instance that contains no hits and whose fit is invalid.
`HTrack(ETrack tre)` Construct and instance from a track and its error.
`HTrack(HTrack ht)` Construct an instance which replicates its argument (Copy Constructor).

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`addHit(Hit hit)` Add a hit to the back of the list.
`double`	`chisquared()` Return the chi-square of the track fit.
`void`	`dropHit()` Drop the last hit on the list.
`void`	`dropHits()` Drop all hits.
`boolean`	`equals(HTrack ht)` Test equality of this object against another HTrack.
`List`	`hits()` Return the list of hits.
`boolean`	`isFit()` Return the fit status: true if track has one or more hits and has been fit with all of its hits.
`TrackMcHitInfo`	`mcInfo()` Return the MC track information for hits on this track.
`ETrack`	`newTrack()` Return a copy of the fit track parameters and errors.
`boolean`	`notEquals(HTrack ht)` Test inequality of this object against another HTrack.
`int`	`numberOfMeasurements()` Return the number of measurements on this track.
`PropStat`	`propagate(Propagator prop, Surface srf)` Propagate the fit track.
`PropStat`	`propagate(Propagator prop, Surface srf, PropDir dir)` Propagate the fit track in a specified direction.
`void`	`setFit(ETrack tre, double chisq)` Set the fit parameters for the current list of hits.
`String`	`toString()` output stream
`ETrack`	`track()` Fetch a handle to the fit track parameters and errors.
`void`	`unsetFit()` Unset the fit.
`void`	`unsetFit(ETrack tre)` Unset the fit and reset the starting track.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - _nfit
```
private int _nfit
```
  - _hits
```
protected List _hits
```
  - _tre
```
protected ETrack _tre
```
  - _chisq
```
protected double _chisq
```
- Constructor Detail
  - HTrack
```
public HTrack()
```
    Construct an instance that contains no hits and whose fit is invalid.
  - HTrack
```
public HTrack(ETrack tre)
```
    Construct and instance from a track and its error. There are no hits on the track.
    
    Parameters:
    tre - The ETrack from which to construct this instance.
  - HTrack
```
public HTrack(HTrack ht)
```
    Construct an instance which replicates its argument (Copy Constructor).
    
    Parameters:
    ht - The HTrack to replicate.
- Method Detail
  - addHit
```
public void addHit(Hit hit)
```
    Add a hit to the back of the list.
    
    Parameters:
    hit - The Hit to add to this track.
  - dropHit
```
public void dropHit()
```
    Drop the last hit on the list. This does not affect the fit status.
  - dropHits
```
public void dropHits()
```
    Drop all hits. This does not affect the fit status.
  - setFit
```
public void setFit(ETrack tre,
          double chisq)
```
    Set the fit parameters for the current list of hits. Be sure to add all relevant hits before invocation. It is assumed the track has been fit with all of its hits. The track and chi-square are assigned the specified value and the number of fitted hits is set to the current number of hits.
    
    Parameters:
    tre - The ETrack which represents the fit parameters and errors.
    chisq - The chi-square of the fit.
  - unsetFit
```
public void unsetFit()
```
    Unset the fit. The number of hits is set to 0 and the chi-square is set to zero. The track is not modified (the last fit becomes the starting track).
  - unsetFit
```
public void unsetFit(ETrack tre)
```
    Unset the fit and reset the starting track. The fit is unset and the track is set to the specified value.
    
    Parameters:
    tre - The ETrack which represents the track parameters and errors.
  - hits
```
public List hits()
```
    Return the list of hits.
    
    Returns:
    The list of hits on this track.
  - newTrack
```
public ETrack newTrack()
```
    Return a copy of the fit track parameters and errors.
    
    Returns:
    The ETrack which represents the track parameters and errors.
  - track
```
public ETrack track()
```
    Fetch a handle to the fit track parameters and errors.
    
    Returns:
    The ETrack which represents the track parameters and errors.
  - chisquared
```
public double chisquared()
```
    Return the chi-square of the track fit.
    
    Returns:
    The chi-square of the track fit.
  - numberOfMeasurements
```
public int numberOfMeasurements()
```
    Return the number of measurements on this track. This is the number of hits times the dimension of the hit measurement.
    
    Returns:
    The number of measurements on this track.
  - mcInfo
```
public TrackMcHitInfo mcInfo()
```
    Return the MC track information for hits on this track.
    
    Returns:
    The TrackMcHitInfo object encapsulating the MC track information for hits on this track.
  - isFit
```
public boolean isFit()
```
    Return the fit status: true if track has one or more hits and has been fit with all of its hits.
    
    Returns:
    true if the track contains a valid fit.
  - propagate
```
public PropStat propagate(Propagator prop,
                 Surface srf)
```
    Propagate the fit track. Note that this does not change the fit status because the propagation should be reversible.
    
    Parameters:
    prop - The Propagator to use for propagation.
    srf - The Surface to propagate to.
    
    Returns:
    The propagation status.
  - propagate
```
public PropStat propagate(Propagator prop,
                 Surface srf,
                 PropDir dir)
```
    Propagate the fit track in a specified direction. Note that this does not change the fit status because the propagation should be reversible.
    
    Parameters:
    prop - The Propagator to use for propagation.
    srf - The Surface to propagate to.
    dir - The direction in which to propagate.
    
    Returns:
    The propagation status.
  - toString
```
public String toString()
```
    output stream
    
    Overrides:
    
    toString in class Object
    
    Returns:
    The String representation of this class.
  - equals
```
public boolean equals(HTrack ht)
```
    Test equality of this object against another HTrack.
    
    Parameters:
    ht - The HTrack against which to compare.
    
    Returns:
    true if the two tracks are equal.
  - notEquals
```
public boolean notEquals(HTrack ht)
```
    Test inequality of this object against another HTrack.
    
    Parameters:
    ht - The HTrack against which to compare.
    
    Returns:
    true if the two tracks are equal.

Class HTrack

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

_nfit

_hits

_tre

_chisq

Constructor Detail

HTrack

HTrack

HTrack

Method Detail

addHit

dropHit

dropHits

setFit

unsetFit

unsetFit

hits

newTrack

track

chisquared

numberOfMeasurements

mcInfo

isFit

propagate

propagate

toString

equals

notEquals