“…Among all such non-Newton calculi, recently great interest has been focused on the Grossman-Katz calculus obtained when we fix α(x) = e x , α −1 (x) = ln(x) and X = R + for the set of real numbers strictly greater than zero [7,12,14,15]. We shall concentrate here on one option, originally called by Grossman and Katz the geometric/exponential/bigeometric calculus [1,2,13,[34][35][36][37], but from which other different terminology and small variations of the original calculus have grown up in the literature, in particular, the multiplicative calculus [3][4][5]8,12,15,36,[38][39][40], and more recently, the proportional calculus [7,11,14,41], which is essentially the bigeometric calculus of [35]. Here we follow closely this last approach-in particular, the exposition of the non-Newton calculus as found in [7,14,35], because it is appealing to scientists who seek ways to express laws in a scale-free form.…”