def t60_millington(surfaces, alpha, volume, c=SOUNDSPEED):
    mean_alpha = np.average(alpha, axis=0, weights=surfaces)
    A = -np.sum(surfaces[:, np.newaxis] * np.log(1.0 - mean_alpha), axis=0)
    t60 = 4.0 * np.log(10.0**6.0) * volume / (c * A)
    return t60
push a copy to the pydata dev directory
dataset/ETHPy150Open python-acoustics/python-acoustics/acoustics/room.py/t60_millington--crossover with--dataset/ETHPy150Open pydata/pandas/doc/make.py/upload_stable_pdf