public void Fill()
{
Matrix2D <int> m = new Matrix2D <int>(3, 3);
Aver.AreEqual("0 0 0\r\n" + "0 0 0\r\n" + "0 0 0", m.ToString());
m.Fill(2);
Aver.AreEqual("2 2 2\r\n" + "2 2 2\r\n" + "2 2 2", m.ToString());
}