- matrix add(matrix const & other) const;
- matrix sub(matrix const & other) const;
- matrix mul(matrix const & other) const;
- ex const & operator() (int ro, int co) const;
- matrix & set(int ro, int co, ex value);
+ matrix add(const matrix & other) const;
+ matrix sub(const matrix & other) const;
+ matrix mul(const matrix & other) const;
+ const ex & operator() (unsigned ro, unsigned co) const;
+ matrix & set(unsigned ro, unsigned co, ex value);