diff --git a/gtsam/navigation/AHRSFactor.h b/gtsam/navigation/AHRSFactor.h
index e5a92ec47..0a67b6b39 100644
--- a/gtsam/navigation/AHRSFactor.h
+++ b/gtsam/navigation/AHRSFactor.h
@@ -140,6 +140,7 @@ class GTSAM_EXPORT AHRSFactor: public NoiseModelFactorN<Rot3, Rot3, Vector3> {
 
 public:
 
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
   /** Shorthand for a smart pointer to a factor */
 #if !defined(_MSC_VER) && __GNUC__ == 4 && __GNUC_MINOR__ > 5
diff --git a/gtsam/navigation/AttitudeFactor.h b/gtsam/navigation/AttitudeFactor.h
index 4339fc5de..743bba1f4 100644
--- a/gtsam/navigation/AttitudeFactor.h
+++ b/gtsam/navigation/AttitudeFactor.h
@@ -82,6 +82,7 @@ class GTSAM_EXPORT Rot3AttitudeFactor: public NoiseModelFactorN<Rot3>, public At
 
 public:
 
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
   /// shorthand for a smart pointer to a factor
   typedef boost::shared_ptr<Rot3AttitudeFactor> shared_ptr;
@@ -156,6 +157,7 @@ class GTSAM_EXPORT Pose3AttitudeFactor: public NoiseModelFactorN<Pose3>,
   typedef NoiseModelFactorN<Pose3> Base;
 
 public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
   /// shorthand for a smart pointer to a factor
diff --git a/gtsam/navigation/BarometricFactor.h b/gtsam/navigation/BarometricFactor.h
index a72b87024..646731a09 100644
--- a/gtsam/navigation/BarometricFactor.h
+++ b/gtsam/navigation/BarometricFactor.h
@@ -38,6 +38,7 @@ class GTSAM_EXPORT BarometricFactor : public NoiseModelFactorN<Pose3, double> {
     double nT_;  ///< Height Measurement based on a standard atmosphere
 
    public:
+    // Provide access to the Matrix& version of evaluateError:
     using Base::evaluateError;
     /// shorthand for a smart pointer to a factor
     typedef boost::shared_ptr<BarometricFactor> shared_ptr;
diff --git a/gtsam/navigation/GPSFactor.h b/gtsam/navigation/GPSFactor.h
index df2b2474f..da6b453eb 100644
--- a/gtsam/navigation/GPSFactor.h
+++ b/gtsam/navigation/GPSFactor.h
@@ -42,6 +42,7 @@ private:
 
 public:
 
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
   /// shorthand for a smart pointer to a factor
   typedef boost::shared_ptr<GPSFactor> shared_ptr;
@@ -120,6 +121,7 @@ private:
   Point3 nT_; ///< Position measurement in cartesian coordinates
 
 public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
   /// shorthand for a smart pointer to a factor
diff --git a/gtsam/navigation/ImuFactor.h b/gtsam/navigation/ImuFactor.h
index e521e6b19..41648674b 100644
--- a/gtsam/navigation/ImuFactor.h
+++ b/gtsam/navigation/ImuFactor.h
@@ -179,6 +179,7 @@ private:
   PreintegratedImuMeasurements _PIM_;
 
 public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
   /** Shorthand for a smart pointer to a factor */
diff --git a/gtsam/navigation/MagPoseFactor.h b/gtsam/navigation/MagPoseFactor.h
index bf64933dc..f0b82eed7 100644
--- a/gtsam/navigation/MagPoseFactor.h
+++ b/gtsam/navigation/MagPoseFactor.h
@@ -49,6 +49,7 @@ class MagPoseFactor: public NoiseModelFactorN<POSE> {
   GTSAM_CONCEPT_POSE_TYPE(POSE)
 
  public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
   ~MagPoseFactor() override {}
diff --git a/gtsam/nonlinear/FunctorizedFactor.h b/gtsam/nonlinear/FunctorizedFactor.h
index 53c92155b..59702ee74 100644
--- a/gtsam/nonlinear/FunctorizedFactor.h
+++ b/gtsam/nonlinear/FunctorizedFactor.h
@@ -65,6 +65,7 @@ class FunctorizedFactor : public NoiseModelFactorN<T> {
   std::function<R(T, OptionalMatrixType)> func_;  ///< functor instance
 
  public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
   /** default constructor - only use for serialization */
   FunctorizedFactor() {}
@@ -166,6 +167,7 @@ class FunctorizedFactor2 : public NoiseModelFactorN<T1, T2> {
   FunctionType func_;  ///< functor instance
 
  public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
   /** default constructor - only use for serialization */
   FunctorizedFactor2() {}
diff --git a/gtsam/nonlinear/NonlinearEquality.h b/gtsam/nonlinear/NonlinearEquality.h
index c026530ec..309cababa 100644
--- a/gtsam/nonlinear/NonlinearEquality.h
+++ b/gtsam/nonlinear/NonlinearEquality.h
@@ -305,6 +305,7 @@ class NonlinearEquality2 : public NoiseModelFactorN<T, T> {
 
  public:
   typedef boost::shared_ptr<NonlinearEquality2<T>> shared_ptr;
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
   /**
diff --git a/gtsam/slam/EssentialMatrixFactor.h b/gtsam/slam/EssentialMatrixFactor.h
index 43bc48b7d..645fb611c 100644
--- a/gtsam/slam/EssentialMatrixFactor.h
+++ b/gtsam/slam/EssentialMatrixFactor.h
@@ -117,6 +117,7 @@ class EssentialMatrixFactor2
   typedef EssentialMatrixFactor2 This;
 
  public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
   /**
    *  Constructor
diff --git a/gtsam/slam/RotateFactor.h b/gtsam/slam/RotateFactor.h
index 1591cbe2f..9caf239f8 100644
--- a/gtsam/slam/RotateFactor.h
+++ b/gtsam/slam/RotateFactor.h
@@ -74,6 +74,7 @@ class RotateDirectionsFactor: public NoiseModelFactorN<Rot3> {
   typedef RotateDirectionsFactor This;
 
 public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
   /// Constructor
diff --git a/gtsam_unstable/dynamics/IMUFactor.h b/gtsam_unstable/dynamics/IMUFactor.h
index 90a37751c..798432f7f 100644
--- a/gtsam_unstable/dynamics/IMUFactor.h
+++ b/gtsam_unstable/dynamics/IMUFactor.h
@@ -32,6 +32,7 @@ protected:
   double dt_; /// time between measurements
 
 public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
   /** Standard constructor */
diff --git a/gtsam_unstable/slam/GaussMarkov1stOrderFactor.h b/gtsam_unstable/slam/GaussMarkov1stOrderFactor.h
index 2f087cedf..6dfd8d295 100644
--- a/gtsam_unstable/slam/GaussMarkov1stOrderFactor.h
+++ b/gtsam_unstable/slam/GaussMarkov1stOrderFactor.h
@@ -53,6 +53,7 @@ private:
   Vector tau_;
 
 public:
+  // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
   // shorthand for a smart pointer to a factor
diff --git a/tests/simulated2D.h b/tests/simulated2D.h
index 7f89d5ac2..e1f0c5116 100644
--- a/tests/simulated2D.h
+++ b/tests/simulated2D.h
@@ -133,6 +133,7 @@ namespace simulated2D {
     typedef boost::shared_ptr<GenericPrior<VALUE> > shared_ptr;
     typedef VALUE Pose; ///< shortcut to Pose type
 	
+    // Provide access to the Matrix& version of evaluateError:
     using Base::evaluateError;
 
     Pose measured_; ///< prior mean
@@ -179,6 +180,7 @@ namespace simulated2D {
     typedef boost::shared_ptr<GenericOdometry<VALUE> > shared_ptr;
     typedef VALUE Pose; ///< shortcut to Pose type
 
+    // Provide access to the Matrix& version of evaluateError:
     using Base::evaluateError;
 
     Pose measured_; ///< odometry measurement
@@ -227,6 +229,7 @@ namespace simulated2D {
     typedef POSE Pose; ///< shortcut to Pose type
     typedef LANDMARK Landmark; ///< shortcut to Landmark type
 
+    // Provide access to the Matrix& version of evaluateError:
     using Base::evaluateError;
 
     Landmark measured_; ///< Measurement