public override double this[
	int r,
	int c
] { get; set; }

Public Overrides Default Property Item ( _
	r As Integer, _
	c As Integer _
) As Double
	Get
	Set

public:
virtual property double default[int r, int c] {
	double get (int r, int c) override;
	void set (int r, int c, double value) override;
}

abstract Item : float with get, set
override Item : float with get, set