HelicalTrackFit (LCSim 3.1.7 API)

java.lang.Object
- org.lcsim.fit.helicaltrack.HelicalTrackFit

```
public class HelicalTrackFit
extends Object
```
Represents the result of a fit to a helical track.

Version:

2.0 (modified by R. Partridge)

Author:

Norman Graf

Field Summary

Fields
Modifier and Type	Field and Description
`private double[]`	`_chisq`
`private SymmetricMatrix`	`_covmatrix`
`private Map<HelicalTrackHit,MultipleScatter>`	`_msmap`
`private int[]`	`_ndf`
`private double`	`_nhchisq`
`private double[]`	`_parameters`
`private Map<HelicalTrackHit,Double>`	`_smap`
`static int`	`curvatureIndex` Index of curvature element in the parameter array and covariance matrix.
`private double`	`curveerror` Doubles used for error variables
`private double`	`dcaerror`
`static int`	`dcaIndex` Index of DCA element in parameter array and covariance matrix.
`private double`	`phi0error`
`static int`	`phi0Index` Index of phi0 element in parameter array and covariance matrix.
`private double`	`slopeerror`
`static int`	`slopeIndex` Index of the slope in the parameter array and covariance matrix.
`private double`	`z0error`
`static int`	`z0Index` Index of the z0 coordinate in the parameter array and covariance matrix.

Constructor Summary

Constructors
Constructor and Description
`HelicalTrackFit(double[] pars, SymmetricMatrix cov, double[] chisq, int[] ndf, Map<HelicalTrackHit,Double> smap, Map<HelicalTrackHit,MultipleScatter> msmap)` Creates a new instance of HelicalTrackFit

Method Summary

Methods
Modifier and Type	Method and Description
`double[]`	`chisq()` Return the helix fit chisqs.
`double`	`chisqtot()` Return the total chisq: chisq[0] + chisq[1] + nhchisq.
`SymmetricMatrix`	`covariance()` Return the helix covariance matrix.
`double`	`cth()` Return cos(theta).
`double`	`curvature()` Return the signed helix curvature.
`double`	`dca()` Return the signed helix DCA.
`double`	`getCurveError()` Return the error for curvature, omega
`double`	`getDcaError()` Return the error for distance of closest approach, dca
`double`	`getPhi0Error()` Return the error for phi0, azimuthal angle of the momentum at the DCA ref.
`double`	`getSlopeError()` Return the error for slope dz/ds, tan(lambda)
`double`	`getZ0Error()` Return the error for z0, the z position of the particle at the DCA
`int[]`	`ndf()` Return the degrees of freedom for the fits.
`double`	`nhchisq()` Return the non-holenomic constraint chisq.
`double`	`p(double bfield)` Return the momentum.
`double[]`	`parameters()` Return the helix parameters as an array.
`Map<HelicalTrackHit,Double>`	`PathMap()` Return a map of x-y path lengths for the hits used in the helix fit.
`double`	`phi0()` Return the azimuthal direction at the DCA
`double`	`pT(double bfield)` Return transverse momentum pT for the helix.
`double`	`R()` Return the radius of curvature for the helix.
`Map<HelicalTrackHit,MultipleScatter>`	`ScatterMap()` Return a map of the MultipleScatter objects supplied for the fit.
`void`	`setnhchisq(double nhchisq)` Set the chisq for non-holonomic constraints (e.g., pT > xx).
`double`	`slope()` Return the helix slope tan(lambda).
`double`	`sth()` Return sin(theta).
`String`	`toString()` Create a string with the helix parameters.
`double`	`x0()`
`double`	`xc()` Return the x coordinate of the helix center/axis.
`double`	`y0()`
`double`	`yc()` Return the y coordinate of the helix center/axis.
`double`	`z0()` Return the z coordinate for the DCA.

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

- Field Detail
  - dcaIndex
```
public static int dcaIndex
```
    Index of DCA element in parameter array and covariance matrix.
  - phi0Index
```
public static int phi0Index
```
    Index of phi0 element in parameter array and covariance matrix.
  - curvatureIndex
```
public static int curvatureIndex
```
    Index of curvature element in the parameter array and covariance matrix.
  - z0Index
```
public static int z0Index
```
    Index of the z0 coordinate in the parameter array and covariance matrix.
  - slopeIndex
```
public static int slopeIndex
```
    Index of the slope in the parameter array and covariance matrix.
  - _chisq
```
private double[] _chisq
```
  - _nhchisq
```
private double _nhchisq
```
  - _ndf
```
private int[] _ndf
```
  - _parameters
```
private double[] _parameters
```
  - _covmatrix
```
private SymmetricMatrix _covmatrix
```
  - _smap
```
private Map<HelicalTrackHit,Double> _smap
```
  - _msmap
```
private Map<HelicalTrackHit,MultipleScatter> _msmap
```
  - curveerror
```
private double curveerror
```
    Doubles used for error variables
  - slopeerror
```
private double slopeerror
```
  - dcaerror
```
private double dcaerror
```
  - phi0error
```
private double phi0error
```
  - z0error
```
private double z0error
```
- Constructor Detail
  - HelicalTrackFit
```
public HelicalTrackFit(double[] pars,
               SymmetricMatrix cov,
               double[] chisq,
               int[] ndf,
               Map<HelicalTrackHit,Double> smap,
               Map<HelicalTrackHit,MultipleScatter> msmap)
```
    Creates a new instance of HelicalTrackFit
    
    Parameters:
    pars - array of helix parameters
    cov - covariance matrix of helix fit
    chisq - chisq of the circle fit (chisq[0]) and s-z fit (chisq[1])
    ndf - dof for the circle fit (ndf[0]) and s-z fit (ndf[1])
    smap - map containing the x-y path lengths
    msmap - map containing the multiple scattering uncertainties
- Method Detail
  - parameters
```
public double[] parameters()
```
    Return the helix parameters as an array.
    
    Returns:
    helix parameters
  - dca
```
public double dca()
```
    Return the signed helix DCA.
    
    Returns:
    DCA
  - phi0
```
public double phi0()
```
    Return the azimuthal direction at the DCA
    
    Returns:
    azimuthal direction
  - curvature
```
public double curvature()
```
    Return the signed helix curvature.
    
    Returns:
    helix curvature
  - z0
```
public double z0()
```
    Return the z coordinate for the DCA.
    
    Returns:
    z coordinate
  - slope
```
public double slope()
```
    Return the helix slope tan(lambda).
    
    Returns:
    slope
  - covariance
```
public SymmetricMatrix covariance()
```
    Return the helix covariance matrix.
    
    Returns:
    covariance matrix
  - chisq
```
public double[] chisq()
```
    Return the helix fit chisqs. chisq[0] is for the circle fit, chisq[1] is for the s-z fit.
    
    Returns:
    chisq array
  - setnhchisq
```
public void setnhchisq(double nhchisq)
```
    Set the chisq for non-holonomic constraints (e.g., pT > xx).
    
    Parameters:
    nhchisq - non-holonomic constraint chisq
  - nhchisq
```
public double nhchisq()
```
    Return the non-holenomic constraint chisq.
    
    Returns:
    non-holenomic constraint chisq
  - chisqtot
```
public double chisqtot()
```
    Return the total chisq: chisq[0] + chisq[1] + nhchisq.
    
    Returns:
    total chisq
  - ndf
```
public int[] ndf()
```
    Return the degrees of freedom for the fits. ndf[0] is for the circle fit and ndf[1] is for the s-z fit.
    
    Returns:
    dof array
  - cth
```
public double cth()
```
    Return cos(theta).
    
    Returns:
    cos(theta)
  - sth
```
public double sth()
```
    Return sin(theta).
    
    Returns:
    sin(theta)
  - pT
```
public double pT(double bfield)
```
    Return transverse momentum pT for the helix.
    
    Parameters:
    bfield - magnetic field
    
    Returns:
    pT
  - p
```
public double p(double bfield)
```
    Return the momentum.
    
    Parameters:
    bfield - magnetic field
    
    Returns:
    momentum
  - R
```
public double R()
```
    Return the radius of curvature for the helix.
    
    Returns:
    radius of curvature
  - xc
```
public double xc()
```
    Return the x coordinate of the helix center/axis.
    
    Returns:
    x coordinate of the helix axis
  - yc
```
public double yc()
```
    Return the y coordinate of the helix center/axis.
    
    Returns:
    y coordinate of the helix axis
  - x0
```
public double x0()
```
  - y0
```
public double y0()
```
  - PathMap
```
public Map<HelicalTrackHit,Double> PathMap()
```
    Return a map of x-y path lengths for the hits used in the helix fit.
    
    Returns:
    path length map
  - ScatterMap
```
public Map<HelicalTrackHit,MultipleScatter> ScatterMap()
```
    Return a map of the MultipleScatter objects supplied for the fit.
    
    Returns:
    map of multiple scattering uncertainties
  - getCurveError
```
public double getCurveError()
```
    Return the error for curvature, omega
    
    Returns:
    a double curveerror
  - getSlopeError
```
public double getSlopeError()
```
    Return the error for slope dz/ds, tan(lambda)
    
    Returns:
    double a slopeerror
  - getDcaError
```
public double getDcaError()
```
    Return the error for distance of closest approach, dca
    
    Returns:
    a double dcaerror
  - getPhi0Error
```
public double getPhi0Error()
```
    Return the error for phi0, azimuthal angle of the momentum at the DCA ref. point
    
    Returns:
    a double phi0error
  - getZ0Error
```
public double getZ0Error()
```
    Return the error for z0, the z position of the particle at the DCA
    
    Returns:
    a double z0error
  - toString
```
public String toString()
```
    Create a string with the helix parameters.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    string containing the helix parameters

Class HelicalTrackFit

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

dcaIndex

phi0Index

curvatureIndex

z0Index

slopeIndex

_chisq

_nhchisq

_ndf

_parameters

_covmatrix

_smap

_msmap

curveerror

slopeerror

dcaerror

phi0error

z0error

Constructor Detail

HelicalTrackFit

Method Detail

parameters

dca

phi0

curvature

z0

slope

covariance

chisq

setnhchisq

nhchisq

chisqtot

ndf

cth

sth

pT

p

R

xc

yc

x0

y0

PathMap

ScatterMap

getCurveError

getSlopeError

getDcaError

getPhi0Error

getZ0Error

toString