def get_d_max(tasks):
    """
    Get the maximum relative deadline among the given periodic tasks.

    Parameters
    ----------
    tasks : list of pSyCH.task.Periodic
        Periodic tasks among which the maximum relative deadline needs to be
        computed.

    Returns
    -------
    float
        Maximum relative deadline among for the give tasks.

    """
    return max([task.d for task in tasks])