def METHOD_NAME(self, r):
    """ a definition of the limiting scheme to use"""
    # minmod limiter Eq. 28
    # val_phi = numpy.maximum(0,numpy.minimum(1,r))
    # superbee limiter Eq. 29
    val_phi = np.maximum(0, np.minimum(2*r, 1), np.minimum(r, 2))
    return val_phi