def transformation_matrix(velocity: float) -> np.ndarray:
    return np.array(
        [
            [gamma(velocity), -gamma(velocity) * beta(velocity), 0, 0],
            [-gamma(velocity) * beta(velocity), gamma(velocity), 0, 0],
            [0, 0, 1, 0],
            [0, 0, 0, 1],
        ]
    )