“…In both ECF and OCF situations, we take x 1 , x 2 , x 3 , x 4 ∈ (0, 1]. 1 In the OCF case, the ratio Q/Q ′ of successive denominators can in fact be any rational number in the interval (0, G), but since in the definition of n R we are interested only in Q R < Q ′ , we can restrict to x 3 1 in the definition of L O,± . The golden ratios G = (1 + √ 5)/2 and g = 1/G = (−1 + √ 5)/2 will be used often.…”