lcsim/src/org/lcsim/util/swim

diff -u -r1.24 -r1.25
--- Helix.java	27 Oct 2006 17:53:14 -0000	1.24
+++ Helix.java	2 Dec 2006 02:39:02 -0000	1.25
@@ -22,7 +22,7 @@

  * For more info on swimming see <a href="doc-files/transport.pdf">this paper</a>
  * by Paul Avery.
  * @author tonyj

- * @version $Id: Helix.java,v 1.24 2006/10/27 17:53:14 jstrube Exp $

+ * @version $Id: Helix.java,v 1.25 2006/12/02 02:39:02 sinev Exp $

  */
 public class Helix implements Trajectory
 {

@@ -184,6 +184,26 @@

 	   double p0z = pz*cos(rho*alpha) + pz*(1-cos(rho*alpha));
 	   return new BasicHep3Vector(p0x, p0y, p0z);
    }

+
+   // added by Nick Sinev
+   public double getSecondDistanceToInfiniteCylinder(double r)
+   {
+    double result = getDistanceToInfiniteCylinder(r);
+    SpacePoint first = getPointAtDistance(result);
+    double angto0 = Math.atan2(-yCenter,-xCenter);
+    double angtofirst = Math.atan2(first.y()-yCenter,first.x()-xCenter);
+    double dang = angtofirst-angto0;
+    if(dang < -Math.PI) dang+= 2.*Math.PI;
+    if(dang > Math.PI) dang-= 2.*Math.PI;
+    double angofarc = 2.*(Math.PI - Math.abs(dang));
+    double arc = Math.abs(radius) * angofarc / cosLambda;
+    return result+arc;
+   }
+
+   public double getZPeriod()
+   {
+       return Math.PI * radius * 2. *sinLambda/cosLambda;
+   }

    
    /**
     * Sets the parametereization in terms of "momentum" and charge