public void CanCheck_Equality()
{
const double a = 3.3;
const double b = 2.2;
const double c = 4.11;
const double d = 1.344;
var ptA = new Point4d(a, b, c, d);
var expectedEqual = new Point4d(a + Settings.Tolerance / 2, b, c, d);
var expectedNotEqual = new Point4d(a + Settings.Tolerance * 2, b, c, d);
Assert.True(ptA == expectedEqual);
Assert.Equal(ptA.GetHashCode(), expectedEqual.GetHashCode());
Assert.True(ptA != expectedNotEqual);
Assert.NotEqual(ptA.GetHashCode(), expectedNotEqual.GetHashCode());
Assert.False(ptA == null);
}