lcsim/src/org/lcsim/fit/helicaltrack

diff -u -r1.27 -r1.28
--- HelicalTrackFitter.java	13 Oct 2008 01:05:58 -0000	1.27
+++ HelicalTrackFitter.java	24 Oct 2008 21:29:20 -0000	1.28
@@ -4,7 +4,7 @@

  *
  * Created on March 25, 2006, 6:11 PM
  *

- * $Id: HelicalTrackFitter.java,v 1.27 2008/10/13 01:05:58 partridge Exp $

+ * $Id: HelicalTrackFitter.java,v 1.28 2008/10/24 21:29:20 partridge Exp $

  */
 
 import hep.physics.matrix.SymmetricMatrix;

@@ -235,8 +235,11 @@

             cov.setElement(HelicalTrackFit.phi0Index, HelicalTrackFit.dcaIndex, -1. * _cfit.cov()[4]);  // fix d0 sign convention
             cov.setElement(HelicalTrackFit.dcaIndex, HelicalTrackFit.dcaIndex, _cfit.cov()[5]);
             

-            //  Calculate the arc lengths from the DCA to each hit

+            //  Calculate the arc lengths from the DCA to each hit and check for backwards hits

             Map<HelicalTrackHit, Double> smap = getPathLengths(hitcol);

+            for (HelicalTrackHit hit : smap.keySet()) {
+                if (smap.get(hit) < 0.) return FitStatus.CircleFitFailed;
+            }

             
             //  Check if we have enough pixel hits to do a straight-line fit of s vs z
             int npix = pixel_hits.size();

@@ -462,8 +465,9 @@

         private CircleFit CircleFix(CircleFit oldfit, List<HelicalTrackHit> hitlist) {
             
             //  Check if we are going around the circle in the right direction by getting

-            //  the path length to the first hit and checking that it is positive
-            double s = HelixUtils.PathLength(oldfit, hitlist.get((0)));

+            //  the path length to the last hit and checking that it is positive
+            int nhits = hitlist.size();
+            double s = HelixUtils.PathLength(oldfit, hitlist.get(nhits - 1));

             if (s > 0.) return oldfit;
             
             //  Reverse the direction by changing the sign of dca, curv, and adding pi to phi0