--- a/pysmcl/range_analysis.py	Mon Jan 04 12:34:09 2010 +0100
+++ b/pysmcl/range_analysis.py	Mon Jan 04 12:54:47 2010 +0100
@@ -5,6 +5,7 @@
 range in a given function. A range is represented as a tuple of two
 numbers or the bottom element.
 """
+import numbers
 import pysmcl.ast_wrapper as ast
 from pysmcl import flow
 import pysmcl.setup as setup
@@ -60,6 +61,12 @@
         covered by that of other. """
         return self.a >= other.a and self.b <= other.b
 
+    def __sub__(self, other):
+        if(isinstance(other, numbers.Number)):
+            return Range(self[0] - other, self[1] - other)
+        else:
+            raise NotImplemented
+
     def __eq__(self, other):
         if isinstance(other, Bottom):
             return False
@@ -112,6 +119,12 @@
         """Combining with bottom yields bottom"""
         return self
 
+    def __sub__(self, other):
+        if(isinstance(other, numbers.Number)):
+            return self
+        else:
+            raise NotImplemented
+
     def __repr__(self):
         return "_|_"
 
@@ -357,10 +370,10 @@
         if node.func.id == "range":
             if(len(node.args) > 1):
                 lower = self.visit(node.args[0])
-                return lower.combine(self.visit(node.args[1]))
+                return lower.combine(self.visit(node.args[1]) - 1)
             else:
                 lower = Range(0, 0)
-                return lower.combine(self.visit(node.args[0]))
+                return lower.combine(self.visit(node.args[0]) - 1)
         if node.func.id == "random_bit":
             return Range(0, 1)
         return full_range(self.prime)