message: Removed Walk() from SparseMatrix().
diff: @@ -406,9 +406,6 @@ public:
  /// Print various sparse matrix staticstics.
  void PrintInfo(std::ostream &out) const;
  - /// Walks the sparse matrix
  - int Walk(int &i, int &j, double &a);
  -
  /// Returns max_{i,j} |(i,j)-(j,i)| for a finalized matrix
  double IsSymmetric() const;
  