Am Montag, 27. Oktober 2008 11:46 schrieb Henning Thielemann: > On Mon, 27 Oct 2008, Janis Voigtlaender wrote: > > Henning Thielemann wrote: > >> I think one reason is that repeated rounding should not be worse than > >> rounding in one go. Consider the rule 'use ceiling when the first > >> removed digit is 5'. Then > >> > >> 0.45 - (round to one place) -> 0.5 - (round to integer) -> 1 > > > > But repeated rounding *is* worse than rounding in one go, under any > > reasonable scheme: > > > > 3.46 -> 3.5 -> 4 > > With the rounding-to-even route this would be > > 3.46 -> 3.4 -> 3
Wait, that cannot be. 6 > 5, so 3.46 -> 3.5 even with banker's rounding. > > so rounding in passes is no worse than rounding in one go for this > example. Rounding in passes is bad per se, because there are pretty large intervals where that gives a different result from a direct rounding. > > > vs. > > > > 3.46 -> 3 > > > > That was actually the debate with that teacher. Unbelievable as that > > still is to me today, she advocated the 3.46 -> 3.5 -> 4 route ... > > I also know a didact which tells teachers that 1 has no prime > decomposition. Oh, I see, she may have copied that from Wikipedia: > http://en.wikipedia.org/wiki/Prime_factorisation I can believe that makes sense to somebody who considers 0 an unnatural number, an empty product must be frightening for them. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
