org.lcsim.recon.cat

Class GarfieldHelix

java.lang.Object

org.lcsim.recon.cat.GarfieldHelix

public final class GarfieldHelix
extends Object

simple helix format for general hits, either 2D or 3D used within the Garfield track finding package for calorimeter assisted tracking with the SiD.

parametrization is redundant. A helix is defined by
- a point on the helix (base)
- direction vector at this point (dir)
- curvature (kappa)
dir is normalized such that the projection of dir into xy plane has length one.

Version:

$Id: GarfieldHelix.java,v 1.1 2007/04/06 21:48:14 onoprien Exp $

Author:

E. von Toerne

See Also:

GarfieldTrackFinder

Field Summary

Fields

Modifier and Type	Field and Description
private double[]	base
private int	debugLevel
private double[]	dir
private static double	k_cm
private double	kappa
private double[]	pointOnHelix
private double	sSave

Constructor Summary

Constructors

Constructor and Description
GarfieldHelix() empty constructor
GarfieldHelix(double[] b, double[] d, double ka)

Method Summary

Methods

Modifier and Type	Method and Description
double[]	base()
double	base(int i)
private double	cosfrac(double x, double ka) cosfrac(x, ka) = (cos(x*ka)-1) / ka
double[]	dir()
double	dir(int i)
double	dirAtPoint(int i)
double	distanceBaseToPoint(double[] p)
double	distanceBaseToPoint(GarfieldHit h) added for convenience and to avoid creating more double vectors
double	distanceToHit2D(GarfieldHit h)
double	distanceToHit3D(double[] pos)
private double	distanceToInterval(double a, double b, double c) returns distance to that interval a,b (0 or the distance to the edge) allows for arbitrary ordering (ab)
double	distanceToLine2D(GarfieldHit h, double px, double py)
double	getCenter(int i)
double	getPointOnHelix(int i)
double	kappa()
private static double	myAbs(double ka) absolute value of a double
void	normalizeDir() normalizes the direction vector.
int	q()
void	setBase(double x, double y, double z)
void	setDebugLevel(int i) controls amount of debug text output and test histograms, =0 not output, >0 debug output
void	setDir(double x, double y, double z)
void	setKappa(double ka)
void	setPointOnHelix(double s)
void	setPointOnHelixWithXY(double x, double y)
void	setPointOnHelixWithZ(double z)
private double	sinfrac(double x, double ka) sinfrac(x, ka) = sin(x*ka) / ka
double	sqr(double x)
double	sSave()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

k_cm

private static double k_cm

base

private double[] base

dir

private double[] dir

kappa

private double kappa

pointOnHelix

private double[] pointOnHelix

sSave

private double sSave

debugLevel

private int debugLevel

Constructor Detail

GarfieldHelix

public GarfieldHelix()

empty constructor

GarfieldHelix

public GarfieldHelix(double[] b,
             double[] d,
             double ka)

Parameters:

b - base (= point on helix)

d - dir (= helix direction vector at base point)

ka - curvature

Method Detail

q

public int q()

sSave

public double sSave()

dir

public double dir(int i)

base

public double base(int i)

dir

public double[] dir()

base

public double[] base()

kappa

public double kappa()

getPointOnHelix

public final double getPointOnHelix(int i)

setDebugLevel

public void setDebugLevel(int i)

controls amount of debug text output and test histograms, =0 not output, >0 debug output

setKappa

public void setKappa(double ka)

setBase

public void setBase(double x,
           double y,
           double z)

setDir

public void setDir(double x,
          double y,
          double z)

sqr

public double sqr(double x)

normalizeDir

public void normalizeDir()

normalizes the direction vector. xy-projection of dir is of length one.

distanceToHit3D

public final double distanceToHit3D(double[] pos)

distanceBaseToPoint

public final double distanceBaseToPoint(double[] p)

distanceBaseToPoint

public final double distanceBaseToPoint(GarfieldHit h)

added for convenience and to avoid creating more double vectors

myAbs

private static final double myAbs(double ka)

absolute value of a double

sinfrac

private final double sinfrac(double x,
             double ka)

sinfrac(x, ka) = sin(x*ka) / ka

cosfrac

private final double cosfrac(double x,
             double ka)

cosfrac(x, ka) = (cos(x*ka)-1) / ka

distanceToInterval

private final double distanceToInterval(double a,
                        double b,
                        double c)

returns distance to that interval a,b (0 or the distance to the edge) allows for arbitrary ordering (ab)

getCenter

public final double getCenter(int i)

setPointOnHelix

public void setPointOnHelix(double s)

setPointOnHelixWithXY

public void setPointOnHelixWithXY(double x,
                         double y)

setPointOnHelixWithZ

public void setPointOnHelixWithZ(double z)

dirAtPoint

public double dirAtPoint(int i)

distanceToLine2D

public double distanceToLine2D(GarfieldHit h,
                      double px,
                      double py)

distanceToHit2D

public double distanceToHit2D(GarfieldHit h)