void TestNegation (Vector4 a, Vector4 expected )
{
// This test asserts the following:
// -a == expected
var result_1a = -a;
Vector4 result_1b; Vector4.Negate(ref a, out result_1b);
Assert.That(result_1a, Is.EqualTo(expected));
Assert.That(result_1b, Is.EqualTo(expected));
}