diff --git a/gtsam/geometry/tests/testCyclic.cpp b/gtsam/geometry/tests/testCyclic.cpp
index f15654b2e..bdf0c3e98 100644
--- a/gtsam/geometry/tests/testCyclic.cpp
+++ b/gtsam/geometry/tests/testCyclic.cpp
@@ -10,8 +10,8 @@
  * -------------------------------------------------------------------------- */
 
 /**
- * @file   testCyclic.cpp
- * @brief  Unit tests for cyclic group
+ * @file   Cyclic.h
+ * @brief  Cyclic group, can act on 2D vector spaces
  * @author Frank Dellaert
  **/
 
@@ -22,17 +22,21 @@ namespace gtsam {
 
 template<size_t N>
 class Cyclic {
-  size_t i_;
+  size_t i_; ///< we just use an unsigned int
 public:
-  static const Cyclic Identity = Cyclic(0);
+  /// Constructor
   Cyclic(size_t i) :
       i_(i) {
   }
+  /// Cast to size_t
+  operator size_t() const {
+    return i_;
+  }
 };
 
 namespace traits {
 template<size_t N> struct identity<Cyclic<N> > {
-  static const Cyclic<N> value = Cyclic<N>::Identity;
+  static const Cyclic<N> value;
   typedef Cyclic<N> value_type;
 };
 template<size_t N> struct group_flavor<Cyclic<N> > {
@@ -42,6 +46,27 @@ template<size_t N> struct group_flavor<Cyclic<N> > {
 
 } // \namespace gtsam
 
+/**
+ * @file   Cyclic.cpp
+ * @brief  Cyclic group implementation
+ * @author Frank Dellaert
+ **/
+
+namespace gtsam {
+
+namespace traits {
+template<size_t N>
+const Cyclic<N> identity<Cyclic<N> >::value = Cyclic<N>(0);
+} // \namespace traits
+
+} // \namespace gtsam
+
+/**
+ * @file   testCyclic.cpp
+ * @brief  Unit tests for cyclic group
+ * @author Frank Dellaert
+ **/
+
 //#include <gtsam/geometry/Cyclic.h>
 #include <gtsam/base/Testable.h>
 #include <CppUnitLite/TestHarness.h>
@@ -49,19 +74,27 @@ template<size_t N> struct group_flavor<Cyclic<N> > {
 using namespace std;
 using namespace gtsam;
 
-BOOST_CONCEPT_ASSERT((GroupConcept<Cyclic<6> >));
+typedef Cyclic<6> G;
 
-/* ************************************************************************* */
-TEST(Cyclic, Constructor) {
-Cyclic<6> g(0);
+//******************************************************************************
+TEST(Cyclic, Concept) {
+  EXPECT_LONGS_EQUAL(0,traits::identity<G>::value);
+  //BOOST_CONCEPT_ASSERT((GroupConcept<Cyclic<6> >));
 //  EXPECT(assert_equal(p1, p2));
 //  EXPECT_LONGS_EQUAL(2,offset2.size());
 }
 
-/* ************************************************************************* */
-int main() {
-TestResult tr;
-return TestRegistry::runAllTests(tr);
+//******************************************************************************
+TEST(Cyclic, Constructor) {
+  G g(0);
+//  EXPECT(assert_equal(p1, p2));
+//  EXPECT_LONGS_EQUAL(2,offset2.size());
 }
-/* ************************************************************************* */
+
+//******************************************************************************
+int main() {
+  TestResult tr;
+  return TestRegistry::runAllTests(tr);
+}
+//******************************************************************************