diff --git a/gtsam.h b/gtsam.h
index ed4bf8425..fb72660d5 100644
--- a/gtsam.h
+++ b/gtsam.h
@@ -1230,9 +1230,19 @@ virtual class Base {
 virtual class Gaussian : gtsam::noiseModel::Base {
   static gtsam::noiseModel::Gaussian* SqrtInformation(Matrix R);
   static gtsam::noiseModel::Gaussian* Covariance(Matrix R);
-  Matrix R() const;
+
   bool equals(gtsam::noiseModel::Base& expected, double tol);
 
+  // access to noise model
+  Matrix R() const;
+  Matrix information() const;
+  Matrix covariance() const;
+
+  // Whitening operations
+  Vector whiten(Vector v) const;
+  Vector unwhiten(Vector v) const;
+  Matrix Whiten(Matrix H) const;
+
   // enabling serialization functionality
   void serializable() const;
 };
@@ -1243,6 +1253,11 @@ virtual class Diagonal : gtsam::noiseModel::Gaussian {
   static gtsam::noiseModel::Diagonal* Precisions(Vector precisions);
   Matrix R() const;
 
+  // access to noise model
+  Vector sigmas() const;
+  Vector invsigmas() const;
+  Vector precisions() const;
+    
   // enabling serialization functionality
   void serializable() const;
 };
@@ -1269,6 +1284,9 @@ virtual class Isotropic : gtsam::noiseModel::Diagonal {
   static gtsam::noiseModel::Isotropic* Variance(size_t dim, double varianace);
   static gtsam::noiseModel::Isotropic* Precision(size_t dim, double precision);
 
+  // access to noise model
+  double sigma() const;
+
   // enabling serialization functionality
   void serializable() const;
 };