message: DOC: fix typo in doxygen documentation
diff: @@ -42,7 +42,7 @@ public:
  /// Creates a matrix of the given height and width.
  explicit Matrix(int h, int w) : Operator(h, w) { }
  - /// Returns whether this matrix instanse is a square matrix.
  + /// Returns whether this matrix instance is a square matrix.
  bool IsSquare() const { return (height==width); };
  /// Returns reference to a_{ij}.
  