diff -u -r1.1 -r1.2
--- TrackToTrackSmallestDistanceToPOCA.java	29 Sep 2005 21:04:50 -0000	1.1
+++ TrackToTrackSmallestDistanceToPOCA.java	14 Oct 2005 17:40:25 -0000	1.2
@@ -1,13 +1,34 @@

 package structural.likelihood; // package org.lcsim.recon.cluster.structural.likelihood;
 

+import hep.physics.vec.BasicHep3Vector;
+import hep.physics.vec.Hep3Vector;
+import hep.physics.vec.VecOp;
+

 import org.lcsim.event.Cluster;

+import org.lcsim.recon.cluster.util.TensorClusterPropertyCalculator;
+import org.lcsim.recon.cluster.util.BasicCluster;
+import org.lcsim.util.swim.Line;

 
 public class TrackToTrackSmallestDistanceToPOCA implements StructuralLikelihoodQuantity
 {
     public TrackToTrackSmallestDistanceToPOCA() {}
 

-    public double evaluate(Cluster track1, Cluster track2) 

+    public double evaluate(Cluster track1, Cluster track2) throws QuantityNotDefinedException

     {

-	throw new AssertionError("Not implemented");

+	if (track1.getCalorimeterHits().size()<4 || track2.getCalorimeterHits().size()<4) {
+	    throw new QuantityNotDefinedException("Need 4+ hits in each cluster to get direction, but they have "
+						  +track1.getCalorimeterHits().size()
+						  +" and "
+						  +track2.getCalorimeterHits().size()
+						  +" respectively.");
+	}
+
+	// Need to find directions of the two clusters.
+	Line line1 = MiscUtilities.makeLine(track1);
+	Line line2 = MiscUtilities.makeLine(track2);
+
+	double[] distancesAlongLinesToPOCAs = Line.getPOCAOfLines(line1, line2);
+
+	return Math.min(Math.abs(distancesAlongLinesToPOCAs[0]), Math.abs(distancesAlongLinesToPOCAs[1]));

     }
 }