public void HashTest()
{
var a = new TensorOld(2, 3);
var b = new TensorOld(2, 3);
Assert.Equal(a, b);
Assert.NotEqual(a.GetHashCode(), b.GetHashCode());
var dict = new Dictionary <TensorOld, int>();
dict.Add(a, 1);
dict.Add(b, 2);
Assert.Equal(1, dict[a]);
Assert.Equal(2, dict[b]);
}