public void TestNormalize()
{
float x = 5, y = 12;
Vector2D v = new Vector2D(x, y);
v.Normalize();
float invLength = 1.0f / (float) System.Math.Sqrt((x * x) + (y * y));
x *= invLength;
y *= invLength;
TestHelper.AssertEquals(x, y, v, "Testing v.Normalize()");
}