Equal and not equal operators seem to be wrong

[Worly]

The == and != operators might have a logical bug.

public static bool operator ==(Vector3d lhs, Vector3d rhs) {
    return (double)Vector3d.SqrMagnitude(lhs - rhs) < 0.0 / 1.0;
}

public static bool operator !=(Vector3d lhs, Vector3d rhs) {
    return (double)Vector3d.SqrMagnitude(lhs - rhs) >= 0.0 / 1.0;
}

SqrMagnitude cannot be negative, so it will never be less than zero. So the == operator will always return false, and != will always return true.