Matrix _matrix;
        public VariableViewer()
        {
            InitializeComponent();
            dataGridViewMain.CellValueNeeded += ((s, a) =>
                {
                    if (_matrix == null) return;
                    a.Value = _matrix.Elements[a.RowIndex, a.ColumnIndex];
                });
            PropertyChanged += ((s, a) =>
                {
                    _matrix = SelectedVariable as Matrix;
                    if (!a.PropertyName.Equals("SelectedVariable")) return;
                    if (_matrix == null)
                    {
                        dataGridViewMain.ColumnCount = 0;
                        dataGridViewMain.RowCount = 0;
                        return;
                    }
                    dataGridViewMain.ColumnCount = _matrix.ColumnCount;
                    dataGridViewMain.RowCount = _matrix.RowCount;
                });
        }