def sj2(x, meanx, N):
    """
    The variance of a set of data points in one bin.

    Args:
        x (array): The flux array (defined as x in Stellingwerf, 1978).
        meanx (float): The mean of x.
        N (int): The number of data points

    Returns:
        The variance of x.

    """
    return sum((x - meanx) ** 2) / (N - 1)
