org.lcsim.util.swim

Interface Trajectory

All Known Implementing Classes:

Helix, HelixYField, Line

public interface Trajectory

A particle trajectory (either a Helix or a Line)

Version:

$Id: Trajectory.java,v 1.8 2007/08/16 21:46:45 jstrube Exp $

Author:

tonyj

Method Summary

Methods

Modifier and Type	Method and Description
double	getDistanceToInfiniteCylinder(double r) Calculates the distance at which the trajectory first reaches radius R.
double	getDistanceToPoint(Hep3Vector point) Obtain the point of closest approach (POCA) of the trajectory to a point.
double	getDistanceToZPlane(double z) Calculate the distance along the trajectory to reach a given Z plane.
SpacePoint	getPointAtDistance(double alpha) Gets a point after traveling distance alpha from the origin along the trajectory
SpaceVector	getUnitTangentAtLength(double alpha) Returns the momentum at a given distance from the origin

Method Detail

getPointAtDistance

SpacePoint getPointAtDistance(double alpha)

Gets a point after traveling distance alpha from the origin along the trajectory

getDistanceToInfiniteCylinder

double getDistanceToInfiniteCylinder(double r)

Calculates the distance at which the trajectory first reaches radius R. Returns Double.NaN if the trajectory does not intercept the cylinder. In principle there could be multiple solutions, so this method should always return the minimum positive solution.

getDistanceToZPlane

double getDistanceToZPlane(double z)

Calculate the distance along the trajectory to reach a given Z plane. Note distance may be negative.

getDistanceToPoint

double getDistanceToPoint(Hep3Vector point)

Obtain the point of closest approach (POCA) of the trajectory to a point. The return value is the distance parameter s, such that getPointAtDistance(s) is the POCA.

Parameters:

point - Point in space to swim to

Returns:

The length parameter s

getUnitTangentAtLength

SpaceVector getUnitTangentAtLength(double alpha)

Returns the momentum at a given distance from the origin

Parameters:

alpha - The length along the trajectory from the origin

Returns:

The momentum at the given distance