diff --git a/gtsam/linear/GaussianFactorGraph.h b/gtsam/linear/GaussianFactorGraph.h
index fc104a961..28b9eab55 100644
--- a/gtsam/linear/GaussianFactorGraph.h
+++ b/gtsam/linear/GaussianFactorGraph.h
@@ -224,6 +224,9 @@ namespace gtsam {
     /** Return only the diagonal of the Hessian A'*A, as a VectorValues */
     VectorValues hessianDiagonal() const;
 
+    /** Return the block diagonal of the Hessian for this factor */
+    std::map<Key,Matrix> hessianBlockDiagonal() const;
+
     /** Solve the factor graph by performing multifrontal variable elimination in COLAMD order using
      *  the dense elimination function specified in \c function (default EliminatePreferCholesky),
      *  followed by back-substitution in the Bayes tree resulting from elimination.  Is equivalent