diff -N TrackUtils.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ TrackUtils.java	12 May 2012 22:20:44 -0000	1.1
@@ -0,0 +1,195 @@

+package org.lcsim.hps.recon.tracking;
+
+//--- hep ---//
+import hep.physics.vec.BasicHep3Vector;
+import hep.physics.vec.Hep3Vector;
+
+//--- org.lcsim ---//
+import org.lcsim.recon.tracking.seedtracker.SeedTrack;
+
+/**
+ * 
+ * @author Omar Moreno <[log in to unmask]>
+ * @version $Id: TrackUtils.java,v 1.1 2012/05/12 22:20:44 omoreno Exp $
+ */
+
+public class TrackUtils {
+
+	SeedTrack track;
+	double[] trackParameters;
+	
+	/**
+	 * 
+	 */
+	public TrackUtils(){
+		track = null;
+	}
+	
+	/**
+	 * 
+	 */
+	public void setTrack(SeedTrack track){
+		this.track = track;
+		trackParameters = new double[9];
+		this.setTrackParameters(track);
+	}
+	
+	/**
+	 * 
+	 */
+	public double getDoca(){
+		return trackParameters[0];
+	}
+	
+	/**
+	 * 
+	 */
+	public double getPhi0(){
+		return trackParameters[1];
+	}
+	
+	/**
+	 * 
+	 */
+	public double getR(){
+		return trackParameters[2];
+	}
+	
+	/**
+	 * 
+	 */
+	public double getX0(){
+		return trackParameters[3];
+	}
+	
+	/**
+	 * 
+	 */
+	public double getY0(){
+		return trackParameters[4];
+	}
+	/**
+	 * 
+	 */
+	public double getZ0(){
+		return trackParameters[5];
+	}
+	
+	/**
+	 * 
+	 */
+	public double getTanLambda(){
+		return trackParameters[6];
+	}
+	
+	/**
+	 * 
+	 */
+	public double getXC(){
+		return trackParameters[7];
+	}
+	
+	/**
+	 * 
+	 */
+	public double getYC(){
+		return trackParameters[8];
+	}
+	
+	/**
+	 * 
+	 */
+	public double getXOnHelixProjection(double y){
+		
+		// Check if a track has been set
+		if(track == null) throw new RuntimeException("Track has not been set!");
+		
+		// Find the x position
+		return this.getXC() 
+				+ Math.signum(this.getR())*Math.sqrt(this.getR()*this.getR() - Math.pow(y-this.getYC(), 2));
+	}
+	
+	/**
+	 * 
+	 */
+	public double getYOnHelixProjection(double x){
+		
+		// Check if a track has been set
+		if(track == null) throw new RuntimeException("Track has not been set!");
+		
+		return this.getYC() 
+				+ Math.signum(this.getR())*Math.sqrt(this.getR()*this.getR() - Math.pow(x-this.getXC(), 2));
+		
+	}
+	
+	/**
+	 * 
+	 */
+	public double arcLength(double x, double y){
+		
+        double phi0 = Math.atan2(this.getY0() - this.getYC(), this.getX0() - this.getXC());
+        double phi = Math.atan2(y - this.getYC(), x - this.getXC());
+        double dphi = phi - phi0;        
+        
+        if (dphi >  Math.PI) dphi -= 2. * Math.PI;
+        if (dphi < -Math.PI) dphi += 2. * Math.PI;
+        
+        return -this.getR()*dphi;
+	}
+	
+	/**
+	 * 
+	 */
+	public void printTrackParameters(){
+		System.out.println(" DOCA: " + this.getDoca() + 
+						   " phi0: " + this.getPhi0() + 
+						   " R: " 	 + this.getR()    +
+						   " x0: " 	 + this.getX0()   +
+						   " y0: "   + this.getY0()   + 
+						   " z0: " 	 + this.getZ0()   + 
+						   " tan(Lambda): " + this.getTanLambda() + 
+						   " xc: "   + this.getXC()   + 
+						   " yc: "   + this.getYC() );
+		
+	}
+	
+	
+	/**
+	 * 
+	 */
+	private void setTrackParameters(SeedTrack track){
+		
+		// All track parameters are in LCSim coordinates system
+		trackParameters[0] = track.getTrackParameter(0);				// DOCA
+		trackParameters[1] = track.getTrackParameter(1);				// phi0
+		trackParameters[2] = 1/track.getTrackParameter(2);				// R
+		trackParameters[3] = -this.getDoca()*Math.sin(this.getPhi0());	// x0
+		trackParameters[4] = this.getDoca()*Math.cos(this.getPhi0());	// y0
+		trackParameters[5] = track.getTrackParameter(3);				// z0
+		trackParameters[6] = track.getTrackParameter(4);				// tan(Lambda)
+		trackParameters[7] = (this.getR() - this.getPhi0())*Math.sin(this.getPhi0());	// xc
+		trackParameters[8] = -(this.getR() - this.getPhi0())*Math.cos(this.getPhi0());	// yc
+	}
+	
+	/**
+	 * 
+	 */
+	public Hep3Vector extrapolateHelixToXPlane(double x){
+		double y = this.getYOnHelixProjection(x);
+		double s = this.arcLength(x, y);
+		double z = this.getZ0() + s*this.getTanLambda();
+		
+		return new BasicHep3Vector(x, y, z);
+	}
+	
+	/**
+	 * 
+	 */
+	public Hep3Vector extrapolateHelixToYPlane(double y){
+		double x = this.getXOnHelixProjection(y);
+		double s = this.arcLength(x, y);
+		double z = this.getZ0() + s*this.getTanLambda();
+		
+		return new BasicHep3Vector(x, y, z);
+	}
+}