diff --git a/gtsam.h b/gtsam.h
index 0e50ac9b6..3222cd2d1 100644
--- a/gtsam.h
+++ b/gtsam.h
@@ -982,6 +982,7 @@ class NonlinearFactorGraph {
   void print(string s) const;
 	double error(const gtsam::Values& c) const;
 	double probPrime(const gtsam::Values& c) const;
+	gtsam::NonlinearFactor* at(size_t i) const;
 	void add(const gtsam::NonlinearFactor* factor);
 	gtsam::Ordering* orderingCOLAMD(const gtsam::Values& c) const;
 	// Ordering* orderingCOLAMDConstrained(const gtsam::Values& c, const std::map<gtsam::Key,int>& constraints) const;
@@ -1132,6 +1133,15 @@ virtual class BetweenFactor : gtsam::NonlinearFactor {
 };
 
 
+template<T = {gtsam::LieVector, gtsam::Point2, gtsam::StereoPoint2, gtsam::Point3, gtsam::Rot2, gtsam::Rot3, gtsam::Pose2, gtsam::Pose3, gtsam::Cal3_S2, gtsam::CalibratedCamera, gtsam::SimpleCamera}>
+virtual class NonlinearEquality : gtsam::NonlinearFactor {
+	// Constructor - forces exact evaluation
+	NonlinearEquality(size_t j, const T& feasible);
+	// Constructor - allows inexact evaluation
+	NonlinearEquality(size_t j, const T& feasible, double error_gain);
+};
+
+
 template<POSE, POINT>
 virtual class RangeFactor : gtsam::NonlinearFactor {
 	RangeFactor(size_t key1, size_t key2, double measured, const gtsam::noiseModel::Base* noiseModel);