Added propagation of mean with averaging

da/baseclasses/statevector.py

@@ -143,7 +143,7 @@ class StateVector(object):
         # If this is not the start of the filter, average previous two optimized steps into the mix
 
         if lag == self.nlag and self.nlag >= 3:
-            NewMean                     += self.EnsembleMembers[lag-2][0].ParameterValues +
+            NewMean                     += self.EnsembleMembers[lag-2][0].ParameterValues + \
                                            self.EnsembleMembers[lag-3][0].ParameterValues 
             NewMean                      = NewMean/3.0
         else: