import math


def evap_fract_time_stiver_mackay(T, theta_wtt, time, k1, k2, k3):
    """
    Return the evaporated fraction []
    source:(Stiver and Mackay, 1984)

    Parameters
    ----------
    T : Temperature [K]
    theta_wtt : Theta without the time [1/s]
    time : Time from the spill [s]
    k1 : empirical constant
    k2 : empirical constant
    k3 : empirical constant

    """
    return T/k1 * math.log(1+(k1*theta_wtt*time)/T) * math.exp(k2 - k3/T)