“…In some cases, when the scale invariance is discrete [16,36,14,32,29,18,2,1], the amplitude of the powerlaw acquires a periodicity, often called log-periodic oscillations: see [35,21] for reviews on the topic. These oscillatory amplitudes are usually more difficult to calculate [13,12,7,26] than the critical exponents. When the scale invariance is associated to a renormalization group map, they can be related to some properties of the map, for example to the shape of its Julia set, see [13,8].…”