diff --git a/doc/Code/LocalizationFactor.cpp b/doc/Code/LocalizationFactor.cpp
index a59a34d27..14f2abd1a 100644
--- a/doc/Code/LocalizationFactor.cpp
+++ b/doc/Code/LocalizationFactor.cpp
@@ -2,6 +2,8 @@ class UnaryFactor: public NoiseModelFactor1<Pose2> {
   double mx_, my_; ///< X and Y measurements
   
 public:
+
+  // Provide access to the Matrix& version of evaluateError:
   using gtsam::NoiseModelFactor1<Pose2>::evaluateError;
 
   UnaryFactor(Key j, double x, double y, const SharedNoiseModel& model):
diff --git a/gtsam/navigation/MagPoseFactor.h b/gtsam/navigation/MagPoseFactor.h
index 8cc243583..d69a0e0a4 100644
--- a/gtsam/navigation/MagPoseFactor.h
+++ b/gtsam/navigation/MagPoseFactor.h
@@ -53,7 +53,6 @@ class MagPoseFactor: public NoiseModelFactorN<POSE> {
   // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
-
   ~MagPoseFactor() override {}
 
   /// Default constructor - only use for serialization.
diff --git a/gtsam/nonlinear/NonlinearFactor.h b/gtsam/nonlinear/NonlinearFactor.h
index 4fc98944f..e65f5d583 100644
--- a/gtsam/nonlinear/NonlinearFactor.h
+++ b/gtsam/nonlinear/NonlinearFactor.h
@@ -36,13 +36,13 @@ namespace gtsam {
 /* ************************************************************************* */
 
 /** These typedefs and aliases will help with making the evaluateError interface
-* independent of boost
-* TODO(kartikarcot): Change this to OptionalMatrixNone
-* This typedef is used to indicate that the Jacobian is not required
-* and the default value used for optional matrix pointer arguments in evaluateError.
-* Had to use the static_cast of a nullptr, because the compiler is not able to
-* deduce the type of the nullptr when expanding the evaluateError templates.
-*/
+ * independent of boost
+ * TODO(kartikarcot): Change this to OptionalMatrixNone
+ * This typedef is used to indicate that the Jacobian is not required
+ * and the default value used for optional matrix pointer arguments in evaluateError.
+ * Had to use the static_cast of a nullptr, because the compiler is not able to
+ * deduce the type of the nullptr when expanding the evaluateError templates.
+ */
 #define OptionalNone static_cast<Matrix*>(nullptr)
 
 /** This typedef will be used everywhere boost::optional<Matrix&> reference was used
@@ -53,7 +53,8 @@ using OptionalMatrixType = Matrix*;
 
 /** The OptionalMatrixVecType is a pointer to a vector of matrices. It will
  * be used in situations where a vector of matrices is optional, like in 
- * unwhitenedError. */
+ * unwhitenedError.
+ */
 using OptionalMatrixVecType = std::vector<Matrix>*;
 
 /**
@@ -254,10 +255,11 @@ public:
   virtual Vector unwhitenedError(const Values& x, OptionalMatrixVecType H = nullptr) const = 0;
 
   /** support taking in the actual vector instead of the pointer as well
-  * to get access to this version of the function from derived classes
-  * one will need to use the "using" keyword and specify that like this:
-  * public:
-  *   using NoiseModelFactor::unwhitenedError; */
+   * to get access to this version of the function from derived classes
+   * one will need to use the "using" keyword and specify that like this:
+   * public:
+   *   using NoiseModelFactor::unwhitenedError;
+   */
   Vector unwhitenedError(const Values& x, std::vector<Matrix>& H) const {
     return unwhitenedError(x, &H);
   }
@@ -613,12 +615,13 @@ protected:
   virtual Vector evaluateError(const ValueTypes&... x,
                                OptionalMatrixTypeT<ValueTypes>... H) const = 0;
 
-  // If someone uses the evaluateError function by supplying all the optional
-  // arguments then redirect the call to the one which takes pointers
-  // to get access to this version of the function from derived classes
-  // one will need to use the "using" keyword and specify that like this:
-  // public:
-  //   using NoiseModelFactorN<list the value types here>::evaluateError;
+  /** If all the optional arguments are matrices then redirect the call to 
+   * the one which takes pointers.
+   * To get access to this version of the function from derived classes
+   * one will need to use the "using" keyword and specify that like this:
+   * public:
+   *   using NoiseModelFactorN<list the value types here>::evaluateError;
+   */
 
   Vector evaluateError(const ValueTypes&... x, MatrixTypeT<ValueTypes>&... H) const {
     return evaluateError(x..., (&H)...);
diff --git a/gtsam/slam/ProjectionFactor.h b/gtsam/slam/ProjectionFactor.h
index 28fd2628f..b263b4de6 100644
--- a/gtsam/slam/ProjectionFactor.h
+++ b/gtsam/slam/ProjectionFactor.h
@@ -52,7 +52,7 @@ namespace gtsam {
   public:
 
     /// shorthand for base class type
-    typedef NoiseModelFactor2<POSE, LANDMARK> Base;
+    typedef NoiseModelFactorN<POSE, LANDMARK> Base;
 
     // Provide access to the Matrix& version of evaluateError:
     using Base::evaluateError;
diff --git a/gtsam_unstable/slam/EquivInertialNavFactor_GlobalVel.h b/gtsam_unstable/slam/EquivInertialNavFactor_GlobalVel.h
index 8a780dfb0..529af878d 100644
--- a/gtsam_unstable/slam/EquivInertialNavFactor_GlobalVel.h
+++ b/gtsam_unstable/slam/EquivInertialNavFactor_GlobalVel.h
@@ -114,7 +114,6 @@ public:
   // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
-
   // shorthand for a smart pointer to a factor
   typedef typename boost::shared_ptr<EquivInertialNavFactor_GlobalVel> shared_ptr;
 
diff --git a/gtsam_unstable/slam/EquivInertialNavFactor_GlobalVel_NoBias.h b/gtsam_unstable/slam/EquivInertialNavFactor_GlobalVel_NoBias.h
index 5ab06adc2..f3e27f7e5 100644
--- a/gtsam_unstable/slam/EquivInertialNavFactor_GlobalVel_NoBias.h
+++ b/gtsam_unstable/slam/EquivInertialNavFactor_GlobalVel_NoBias.h
@@ -112,7 +112,6 @@ public:
   // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
-
   // shorthand for a smart pointer to a factor
   typedef typename boost::shared_ptr<EquivInertialNavFactor_GlobalVel_NoBias> shared_ptr;
 
diff --git a/gtsam_unstable/slam/GaussMarkov1stOrderFactor.h b/gtsam_unstable/slam/GaussMarkov1stOrderFactor.h
index f151dd63e..73f2ceb47 100644
--- a/gtsam_unstable/slam/GaussMarkov1stOrderFactor.h
+++ b/gtsam_unstable/slam/GaussMarkov1stOrderFactor.h
@@ -57,7 +57,6 @@ public:
   // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
-
   // shorthand for a smart pointer to a factor
   typedef typename boost::shared_ptr<GaussMarkov1stOrderFactor> shared_ptr;
 
diff --git a/gtsam_unstable/slam/InertialNavFactor_GlobalVelocity.h b/gtsam_unstable/slam/InertialNavFactor_GlobalVelocity.h
index f1f118c2d..40fc9da25 100644
--- a/gtsam_unstable/slam/InertialNavFactor_GlobalVelocity.h
+++ b/gtsam_unstable/slam/InertialNavFactor_GlobalVelocity.h
@@ -99,7 +99,6 @@ public:
   // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
-
   // shorthand for a smart pointer to a factor
   typedef typename boost::shared_ptr<InertialNavFactor_GlobalVelocity> shared_ptr;
 
diff --git a/gtsam_unstable/slam/InvDepthFactor3.h b/gtsam_unstable/slam/InvDepthFactor3.h
index 3891cc41c..c620bbc87 100644
--- a/gtsam_unstable/slam/InvDepthFactor3.h
+++ b/gtsam_unstable/slam/InvDepthFactor3.h
@@ -39,7 +39,6 @@ public:
   // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
-
   /// shorthand for this class
   typedef InvDepthFactor3<POSE, LANDMARK, INVDEPTH> This;
 
diff --git a/gtsam_unstable/slam/InvDepthFactorVariant1.h b/gtsam_unstable/slam/InvDepthFactorVariant1.h
index 7372e9ebb..af0bcba55 100644
--- a/gtsam_unstable/slam/InvDepthFactorVariant1.h
+++ b/gtsam_unstable/slam/InvDepthFactorVariant1.h
@@ -39,7 +39,6 @@ public:
   // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
-
   /// shorthand for this class
   typedef InvDepthFactorVariant1 This;
 
diff --git a/gtsam_unstable/slam/InvDepthFactorVariant2.h b/gtsam_unstable/slam/InvDepthFactorVariant2.h
index 8284cd9ba..b6ce1a890 100644
--- a/gtsam_unstable/slam/InvDepthFactorVariant2.h
+++ b/gtsam_unstable/slam/InvDepthFactorVariant2.h
@@ -41,7 +41,6 @@ public:
   // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
-
   /// shorthand for this class
   typedef InvDepthFactorVariant2 This;
 
diff --git a/gtsam_unstable/slam/InvDepthFactorVariant3.h b/gtsam_unstable/slam/InvDepthFactorVariant3.h
index e90a2e609..e8c2781d4 100644
--- a/gtsam_unstable/slam/InvDepthFactorVariant3.h
+++ b/gtsam_unstable/slam/InvDepthFactorVariant3.h
@@ -39,7 +39,6 @@ public:
   // Provide access to the Matrix& version of evaluateError:
   using Base::evaluateError;
 
-
   /// shorthand for this class
   typedef InvDepthFactorVariant3a This;
 
diff --git a/gtsam_unstable/slam/TransformBtwRobotsUnaryFactor.h b/gtsam_unstable/slam/TransformBtwRobotsUnaryFactor.h
index 991ff4264..5745536e0 100644
--- a/gtsam_unstable/slam/TransformBtwRobotsUnaryFactor.h
+++ b/gtsam_unstable/slam/TransformBtwRobotsUnaryFactor.h
@@ -186,6 +186,9 @@ namespace gtsam {
     }
 
     /* ************************************************************************* */
+    /** A function overload to accept a vector<matrix> instead of a pointer to
+     * the said type.
+     */
     gtsam::Vector whitenedError(const gtsam::Values& x, std::vector<Matrix>& H) const {
 	  return whitenedError(x, &H);
     }
diff --git a/gtsam_unstable/slam/TransformBtwRobotsUnaryFactorEM.h b/gtsam_unstable/slam/TransformBtwRobotsUnaryFactorEM.h
index fabc40810..d28dd32cd 100644
--- a/gtsam_unstable/slam/TransformBtwRobotsUnaryFactorEM.h
+++ b/gtsam_unstable/slam/TransformBtwRobotsUnaryFactorEM.h
@@ -179,6 +179,9 @@ namespace gtsam {
 
 
     /* ************************************************************************* */
+    /** A function overload to accept a vector<matrix> instead of a pointer to
+     * the said type.
+     */
     Vector whitenedError(const Values& x, OptionalMatrixVecType H = nullptr) const {
 
       bool debug = true;