class element
{
    public:
    class bd_mat_local
    {

       // data members.
    }
    class bd_mat_master
    {

       //data members.
    }
    void set_bd_mat_local();
    void set_bd_mat_master();

private:
    Matrix bdmat;
    bd_mat_local* local;
    bd_mat_master* master;
}