def pRDP_asymp_subsampled_gaussian_best_case(params, alpha):
    """
    :param params:
    :param alpha: The order of the Renyi Divergence
    :return: Evaluation of the pRDP's epsilon

    See Example 20 of Wang, Balle, Kasiviswanathan (2018)
    """
    sigma = params['sigma']
    prob = params['prob']
    n = params['n']
    assert((prob<1) and (prob >= 0))

    # The example where we have an approximately best case data set
    return prob**2 / (2*sigma**2 + prob*(n-1.0/n)/2) * alpha