Remove multiples variables initializations

HySoP/hysop/problem/problem.py

@@ -75,9 +75,13 @@ class Problem(object):
         self.timer = Timer(t_end, dt)
         if  __VERBOSE__:
             print "==== Variables initialization ===="
+        var_list = []
         for op in self.operators:
             for v in op.variables:
-                v.initialize()
+                var_list.append(v)
+        # List of unique elements (initialize once each variable)
+        for v in set(var_list):
+            v.initialize()
         if __VERBOSE__:
             print "===="
         for op in self.operators: