diff --git a/src/__init__.py b/src/__init__.py
index d0dcd640f093a951faf1ee55583f8d3ba2f3239a..ab2b0bcb0a18975974400ca9f33c576e4931a57f 100644
--- a/src/__init__.py
+++ b/src/__init__.py
@@ -25,6 +25,15 @@ def factorial(n):
 
 
 
+def norm_2(iterable):
+    return sum(i**2 for i in iterable)**0.5
+
+def norm_p(iterable):
+    return sum(i**p for i in iterable)**(1/p)
+
+
+
+
 # Data structures ------------------------------------------------------------
 class Record(object):
     def __init__(self, valuedict=None, exclude=["self"], **kwargs):
diff --git a/src/log.py b/src/log.py
index 36130db3be92f987d1a18b1a17279355d94a3211..f2f293712654cdd42084023a638f6a5475a71690 100644
--- a/src/log.py
+++ b/src/log.py
@@ -19,8 +19,9 @@ class LogQuantity:
         self.name = name
         self.unit = unit
         self.description = description
-
-    default_aggregator = None
+    
+    @property
+    def default_aggregator(self): return None
 
     def __call__(self):
         """Return the current value of the diagnostic represented by this 
@@ -44,10 +45,12 @@ class CallableLogQuantityAdapter(LogQuantity):
 
 # manager functionality -------------------------------------------------------
 class _QuantityData:
-    def __init__(self, quantity, interval=1, table=None):
+    def __init__(self, quantity, interval=1, table=None, default_aggregator=None):
         self.quantity = quantity
         self.interval = interval
 
+        self.default_aggregator = default_aggregator or quantity.default_aggregator
+
         if table is None:
             from pytools.datatable import DataTable
             self.table = DataTable(["step", "rank", "value"])
@@ -337,13 +340,15 @@ class LogManager:
         save_buffers = dict(
                 (name, _QuantityData(
                     LogQuantity(
-                        qbuf.quantity.name,
-                        qbuf.quantity.unit,
-                        qbuf.quantity.description,
+                        qdat.quantity.name,
+                        qdat.quantity.unit,
+                        qdat.quantity.description,
                         ),
-                    qbuf.interval,
-                    qbuf.table))
-                for name, qbuf in self.quantity_data.iteritems())
+                    qdat.interval,
+                    qdat.table,
+                    qdat.default_aggregator,
+                    ))
+                for name, qdat in self.quantity_data.iteritems())
 
         from cPickle import dump, HIGHEST_PROTOCOL
         dump((save_buffers, self.constants, self.is_parallel), 
@@ -429,12 +434,12 @@ class LogManager:
         for dep_idx, dep in enumerate(deps):
             if isinstance(dep, Variable):
                 name = dep.name
-                agg_func = self.quantity_data[name].quantity.default_aggregator
+                agg_func = self.quantity_data[name].default_aggregator
                 if agg_func is None: 
                     if self.is_parallel:
                         raise ValueError, "must specify explicit aggregator for '%s'" % name
                     else:
-                        agg_func = max # use something simple
+                        agg_func = lambda lst: lst[0]
             elif isinstance(dep, Lookup):
                 assert isinstance(dep.aggregate, Variable)
                 name = dep.aggregate.name
@@ -471,7 +476,8 @@ class LogManager:
             quantity = self.quantity_data[name].quantity
 
             from pytools import Record
-            this_dep_data = Record(name=name, quantity=quantity, agg_func=agg_func,
+            this_dep_data = Record(name=name, quantity=quantity, 
+                    agg_func=agg_func,
                     varname="logvar%d" % dep_idx, expr=dep)
             dep_data.append(this_dep_data)
 
@@ -515,7 +521,8 @@ class LogManager:
         self.next_watch_tick = self.tick_count + int(max(1, ticks_per_sec))
 
         if self.mpi_comm is not None:
-            self.next_watch_tick = broadcast(self.mpi_comm, next_watch_tick, self.head_rank)
+            self.next_watch_tick = broadcast(self.mpi_comm, 
+                    self.next_watch_tick, self.head_rank)
 
 
 
@@ -550,8 +557,6 @@ class LogUpdateDuration(LogQuantity):
         LogQuantity.__init__(self, name, "s", "Time spent updating the log")
         self.log_manager = mgr
 
-    default_aggregator = max
-
     def __call__(self):
         return self.log_manager.t_log
 
@@ -585,8 +590,6 @@ class TimestepCounter(LogQuantity):
         LogQuantity.__init__(self, name, "1", "Timesteps")
         self.steps = 0
 
-    default_aggregator = max
-
     def __call__(self):
         result = self.steps
         self.steps += 1
@@ -603,8 +606,6 @@ class TimestepDuration(LogQuantity):
 
         self.last_start = time()
 
-    default_aggregator = max
-
     def __call__(self):
         now = time()
         result = now - self.last_start
@@ -646,8 +647,6 @@ class SimulationTime(LogQuantity):
         self.dt = dt
         self.t = 0
 
-    default_aggregator = max
-
     def set_dt(self, dt):
         self.dt = dt