--- a/python/moving.py	Sun Nov 07 01:34:43 2010 -0500
+++ b/python/moving.py	Sun Nov 07 04:21:26 2010 -0500
@@ -66,7 +66,7 @@
         return self
 
     def next(self):
-        if self.iterInstantNum >= self.length():
+        if self.iterInstantNum >= self.length()-1:
             raise StopIteration
         else:
             self.iterInstantNum += 1
@@ -139,6 +139,10 @@
         return [self.x, self.y]
 
     @staticmethod
+    def dot(p1, p2):
+        return p1.x*p2.x+p1.y*p2.y
+
+    @staticmethod
     def distanceNorm2(p1, p2):
         return (p1-p2).norm2()
 
@@ -307,6 +311,12 @@
     def getVelocityAt(self, i):
         return self.velocities[i]
 
+    def getPositionAtInstant(self, i):
+        return self.positions[i-self.getFirstInstant()]
+
+    def getVelocityAtInstant(self, i):
+        return self.velocities[i-self.getFirstInstant()]
+
     def getXCoordinates(self):
         return self.positions.getXCoordinates()
     
@@ -334,7 +344,19 @@
                 instants.append(self.timeInterval[i]*(1-ratio)+ratio*self.timeInterval[i+1])
         return instants
 
-    # def computeVelocities(self):
+    @staticmethod
+    def collisionCourseDotProduct(movingObject1, movingObject2, instant):
+        'A positive result indicates that the road users are getting closer'
+        deltap = movingObject1.getPositionAtInstant(instant)-movingObject2.getPositionAtInstant(instant)
+        deltav = movingObject2.getVelocityAtInstant(instant)-movingObject1.getVelocityAtInstant(instant)
+        return moving.Point.dot(deltap, deltav)
+
+    @staticmethod
+    def collisionCourseCosine(movingObject1, movingObject2, instant):
+        'A positive result indicates that the road users are getting closer'
+        deltap = movingObject1.getPositionAtInstant(instant)-movingObject2.getPositionAtInstant(instant)
+        deltav = movingObject2.getVelocityAtInstant(instant)-movingObject1.getVelocityAtInstant(instant)
+        return moving.Point.dot(deltap, deltav)/(deltap.norm2()*deltav.norm2())
 
 def plotRoadUsers(objects, colors):
     '''Colors is a PlottingPropertyValues instance'''
@@ -366,9 +388,8 @@
     field mostSevereIsMax is True 
     if the most severe value taken by the indicator is the maximum'''
 
-    def __init__(self, name, values, mostSevereIsMax=True, ignoredValue = None): 
-        # , timeInterval=None # implement later
-        TemporalIndicator.__init__(self, name, values, timeInterval=None)
+    def __init__(self, name, values, timeInterval=None, mostSevereIsMax=True, ignoredValue = None): 
+        TemporalIndicator.__init__(self, name, values, timeInterval)
         self.mostSevereIsMax = mostSevereIsMax
         self.ignoredValue = ignoredValue