On Dec 9, 2011, at 3:31 PM, Daniel King wrote: > On Fri, Dec 9, 2011 at 15:27, Carl Eastlund <c...@ccs.neu.edu> wrote: >> What does "divides" even mean in Q? I think we need David to explain >> what his extension of GCD and LCM means here, in that "divisors" and >> "multiples" are fairly trivial things in Q. > > I don't suppose to understand all the math on this page, but I think > it uses the same definition that dvh is using. > > http://mathworld.wolfram.com/GreatestCommonDivisor.html
Interesting: the Mathematica people have extended the gcd function from the integers to the rationals, not by applying the usual definition of gcd to Q (which would indeed be silly, as everything except 0 divides everything else), but by coming up with a different definition which, when restricted to integers, happens to coincide with the usual definition of gcd. I would wonder: is this the ONLY "reasonable" function on rationals which, when restricted to integers, coincides with the usual definition of gcd? Stephen Bloch sbl...@adelphi.edu _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
