diff -u -r1.15 -r1.16
--- TrackUtils.java	9 Feb 2013 00:34:16 -0000	1.15
+++ TrackUtils.java	13 Feb 2013 18:20:54 -0000	1.16
@@ -27,7 +27,7 @@

 /**
  * 
  * @author Omar Moreno <[log in to unmask]>

- * @version $Id: TrackUtils.java,v 1.15 2013/02/09 00:34:16 phansson Exp $

+ * @version $Id: TrackUtils.java,v 1.16 2013/02/13 18:20:54 phansson Exp $

  * TODO: Switch to JLab coordinates
  */
 

@@ -426,22 +426,38 @@

             //This is how I do it with HelicalTrackFits
             double s = HelixUtils.PathToXPlane(track, hth.x(), 0, 0).get(0);
             //System.out.printf("x %f s %f smap %f\n",hth.x(),s,s_wrong);

+            if(Double.isNaN(s)) {
+                double x0 = track.x0();
+                double y0 = track.y0();
+
+                double xc=track.xc();
+                double yc=track.yc();
+                double RC = track.R();
+                double y=yc+Math.signum(RC)*Math.sqrt(RC*RC-Math.pow(hth.x()-xc,2));
+                System.out.printf("calculateTrackHitResidual: s is NaN. p=%.3f RC=%.3f, x=%.3f, xc=%.3f\n",track.p(-0.491),RC,hth.x(),xc);
+            }         
+            

             Hep3Vector posOnHelix = HelixUtils.PointOnHelix(track, s);
             double resy = hth.y() - posOnHelix.y();
             double erry = includeMS ? wrphi : drphi_res;

-

-            residuals.put("resy", resy);
-            residuals.put("erry", erry);
-            residuals.put("drphi", drphi_res);
-            residuals.put("msdrphi",msdrphi);
-
-

             //Now the residual for the "measurement" direction z
             double resz = hth.z() - posOnHelix.z();
             double dz_res = HitUtils.zres(hth, msmap, track);
             double dz_res2 = hth.getCorrectedCovMatrix().diagonal(2);

+
+            if(Double.isNaN(resy)) {
+                System.out.printf("calculateTrackHitResidual: resy is NaN. hit at %s posOnHelix=%s path=%.3f wrong_path=%.3f helix:\n%s\n",hth.getCorrectedPosition().toString(),posOnHelix.toString(),s,s_wrong,track.toString());
+                resy=-9999999.9;
+                resz=-9999999.9;
+            
+            }
+

+            residuals.put("resy", resy);
+            residuals.put("erry", erry);
+            residuals.put("drphi", drphi_res);
+            residuals.put("msdrphi",msdrphi);

 
             residuals.put("resz",resz);
             residuals.put("errz",dz_res);