def logistic(x, A, u, d, v, y0):
 y = ((A / (1 + np.exp(((((4 * u) / A) * (d - x)) + 2)))) + y0)
 return y

def logistic ( x , A , u , d , v , y0 ) : y = ( ( A / ( 1 + np . exp ( ( ( ( ( 4 * u ) / A ) * ( d - x ) ) + 2 ) ) ) ) + y0 ) return y
logistic growth model proposed in zwietering et al .