def flux(rho, u_max, rho_max):
    """
    Computes the traffic flux F = V * rho.

    Parameters
    ----------
    rho : numpy.ndarray
       Traffic density along the road as a 1D array of floats.
    u_max : float
        Maximum speed allowed on the road.
    rho_max : float
        Maximum car density allowed on the road.

    Returns
    -------
    F : numpy.ndarray
        The traffic flux along the road as a 1D array of floats.
    """
    F = rho * u_max * (1.0 - rho / rho_max)
    return F