import math


def neg_exp_distribute(mean_time, U):
    """
    Generate series satisfied negative exponential distribution

    X = -mean*lnU
    
    Parameters:
    -----------
    mean_time: mean time
    U: a list as a parameter for negative exponential time

    Return:
    -------
    X: Generated time (interarrival time or service time)
    """
    return [-1.0*mean_time*math.log(u) for u in U]