def t_dithering(info_dict):
    """ Compute the time wasted due to dithering
    
    Parameters
    ----------
    info_dict: dictionary
   
    Returns
    -------
    t_dithering: float
                 time wasted due to dithering in seconds
    """
    t_dithering=0.
    info_dict['T_dithering']=t_dithering
    return info_dict