diff --git a/cpp/ConditionalGaussian.h b/cpp/ConditionalGaussian.h
index 83c68aea4..1fca89b5f 100644
--- a/cpp/ConditionalGaussian.h
+++ b/cpp/ConditionalGaussian.h
@@ -91,10 +91,10 @@ namespace gtsam {
     const Matrix& get_R() const {return R_;}
 
     /** STL like, return the iterator pointing to the first node */
-    const_iterator const parentsBegin(){ return parents_.begin(); }
+    const_iterator const parentsBegin() const { return parents_.begin(); }
 
     /** STL like, return the iterator pointing to the last node */
-    const_iterator const parentsEnd(){ return parents_.end(); }
+    const_iterator const parentsEnd() const { return parents_.end(); }
 
     /** find the number of parents */
     size_t size() const {return parents_.size();}
diff --git a/cpp/FGConfig.h b/cpp/FGConfig.h
index 1701343f5..4e70209b2 100644
--- a/cpp/FGConfig.h
+++ b/cpp/FGConfig.h
@@ -33,7 +33,7 @@ namespace gtsam {
     virtual ~FGConfig() {};
 
     /** return all the nodes in the graph **/
-    std::vector<std::string> get_names(){
+    std::vector<std::string> get_names() {
       std::vector<std::string> names;
       for(iterator it=values.begin(); it!=values.end(); it++)
         names.push_back(it->first);
diff --git a/cpp/FactorGraph.h b/cpp/FactorGraph.h
index 48c6505d6..13016db9f 100644
--- a/cpp/FactorGraph.h
+++ b/cpp/FactorGraph.h
@@ -37,7 +37,7 @@ namespace gtsam {
   public:
 
     /** get the factors to a specific node */
-      const std::list<int>& get_factors_to_node(const std::string& key) {
+      const std::list<int>& get_factors_to_node(const std::string& key) const {
       return node_to_factors_[key];
     }
 
diff --git a/cpp/LinearFactor.h b/cpp/LinearFactor.h
index bdbd51fb7..47b8b0475 100644
--- a/cpp/LinearFactor.h
+++ b/cpp/LinearFactor.h
@@ -105,10 +105,10 @@ public:
 	std::size_t size() const { return As.size();}
 
 	/** STL like, return the iterator pointing to the first node */
-	const_iterator const begin() { return As.begin();}
+	const_iterator const begin() const { return As.begin();}
 
 	/** STL like, return the iterator pointing to the last node */
-	const_iterator const end() { return As.end();	}
+	const_iterator const end() const { return As.end();	}
 
 	/** check if empty */
 	bool empty() const { return b.size() == 0;}
@@ -142,7 +142,7 @@ public:
 	 * return the number of rows from the b vector
 	 * @return a integer with the number of rows from the b vector
 	 */
-	int numberOfRows() { return b.size();}
+	int numberOfRows() const { return b.size();}
 
 	/**
 	 * Find all variables and their dimensions
diff --git a/cpp/Matrix.cpp b/cpp/Matrix.cpp
index b747e058f..03eff4272 100644
--- a/cpp/Matrix.cpp
+++ b/cpp/Matrix.cpp
@@ -86,7 +86,7 @@ Matrix diag(const Vector& v) {
 /* ************************************************************************* */
 /** Check if two matrizes are the same                                       */
 /* ************************************************************************* */
-bool equal_with_abs_tol(const Matrix& A, const Matrix& B, double tol){
+bool equal_with_abs_tol(const Matrix& A, const Matrix& B, double tol) {
 
   size_t n1 = A.size2(), m1 = A.size1();
   size_t n2 = B.size2(), m2 = B.size1();
diff --git a/cpp/Matrix.h b/cpp/Matrix.h
index 801f3100a..2462f2360 100644
--- a/cpp/Matrix.h
+++ b/cpp/Matrix.h
@@ -76,7 +76,7 @@ bool assert_equal(const Matrix& A, const Matrix& B, double tol = 1e-9);
 /**
  * overload * for matrix-vector multiplication (as BOOST does not)
  */
-inline Vector operator*(const Matrix& A, const Vector & v)  { 
+inline Vector operator*(const Matrix& A, const Vector & v) {
   if (A.size2()!=v.size()) throw(std::invalid_argument("Matrix operator* : A.n!=v.size"));
   return Vector(prod(A,v));
 }
diff --git a/cpp/NonlinearFactor.h b/cpp/NonlinearFactor.h
index 7997b5bc9..7dbe52a23 100644
--- a/cpp/NonlinearFactor.h
+++ b/cpp/NonlinearFactor.h
@@ -111,7 +111,7 @@ namespace gtsam {
     /** Check if two factors are equal */
     bool equals(const Factor& f, double tol=1e-9) const;
 
-    std::string dump() {return "";}
+    std::string dump() const {return "";}
   };
 
   /* ************************************************************************* */
diff --git a/cpp/NonlinearFactorGraph.cpp b/cpp/NonlinearFactorGraph.cpp
index c0db8471c..da065d3f8 100644
--- a/cpp/NonlinearFactorGraph.cpp
+++ b/cpp/NonlinearFactorGraph.cpp
@@ -118,7 +118,7 @@ bool NonlinearFactorGraph::check_convergence(const FGConfig& config1,
 		const FGConfig& config2,
 		double relativeErrorTreshold,
 		double absoluteErrorTreshold,
-		int verbosity)
+		int verbosity) const
 {
 	double currentError = calculate_error(*this, config1, verbosity);
 	double newError     = calculate_error(*this, config2, verbosity);
@@ -211,7 +211,7 @@ pair<LinearFactorGraph, FGConfig> NonlinearFactorGraph::OneIterationLM( FGConfig
 		double absoluteErrorTreshold,
 		int verbosity,
 		double lambda0,
-		double lambdaFactor) {
+		double lambdaFactor) const {
 
 	double lambda = lambda0;
 	bool converged = false;
diff --git a/cpp/NonlinearFactorGraph.h b/cpp/NonlinearFactorGraph.h
index 996e698ce..90ead895c 100644
--- a/cpp/NonlinearFactorGraph.h
+++ b/cpp/NonlinearFactorGraph.h
@@ -71,7 +71,7 @@ public: // these you will probably want to use
 	bool check_convergence(const FGConfig& config1,
 			const FGConfig& config2,
 			double relativeErrorTreshold, double absoluteErrorTreshold,
-			int verbosity = 0);
+			int verbosity = 0) const;
 
 	/**
 	 * Optimize using Levenberg-Marquardt. Really Levenberg's
@@ -105,7 +105,7 @@ public: // these you will probably want to use
 			double absoluteErrorTreshold,
 			int verbosity,
 			double lambda0,
-			double lambdaFactor) ;
+			double lambdaFactor) const ;
 
 };
 }
diff --git a/cpp/Ordering.cpp b/cpp/Ordering.cpp
index ade78a67b..fc587bc45 100644
--- a/cpp/Ordering.cpp
+++ b/cpp/Ordering.cpp
@@ -23,7 +23,7 @@ void Ordering::print() const {
 }
 
 /* ************************************************************************* */
-bool Ordering::equals(Ordering &ord){	
+bool Ordering::equals(Ordering &ord){
 	if(this->size() != ord.size())
 		return false;
 	
diff --git a/cpp/Point2.h b/cpp/Point2.h
index 93b25f73f..7ccb6c503 100644
--- a/cpp/Point2.h
+++ b/cpp/Point2.h
@@ -45,7 +45,7 @@ namespace gtsam {
     }
 
     /** operators */
-    inline bool   operator ==(const Point2& q) {return x_==q.x_ && q.y_==q.y_;}
+    inline bool   operator ==(const Point2& q) const {return x_==q.x_ && q.y_==q.y_;}
     inline Point2 operator + (const Point2& q) const {return Point2(x_+q.x_,y_+q.y_);}
     inline Point2 operator - (const Point2& q) const {return Point2(x_-q.x_,y_-q.y_);}
 
diff --git a/cpp/Point3.h b/cpp/Point3.h
index bc25dcfc8..64293c301 100644
--- a/cpp/Point3.h
+++ b/cpp/Point3.h
@@ -67,7 +67,7 @@ namespace gtsam {
     bool equals(const Point3& p, double tol = 1e-9) const;
 
     /** friends */
-    friend Point3 cross(const Point3 &p1, const Point3 &p2); 
+    friend Point3 cross(const Point3 &p1, const Point3 &p2);
 
   private:
     /** Serialization function */