Re: warning for Round[Log[2]/Log[4]]

*To*: mathgroup at smc.vnet.net*Subject*: [mg13940] Re: warning for Round[Log[2]/Log[4]]*From*: bruck at math.usc.edu (Ronald Bruck)*Date*: Tue, 8 Sep 1998 02:52:36 -0400*Organization*: University of Southern California, Los Angeles, CA*References*: <6ssvo6$m9r@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

In article <6ssvo6$m9r at smc.vnet.net>, Wouter Meeussen <eu000949 at pophost.eunet.be> wrote: >** this is not a bug report *** > Windows 3.0.0.0. > [That Mathematica didn't have enough precision to compute Round[Log[2]/Log[4]] Hmmm. Interesting. Since Log[2]/Log[4] = 1/2, Mathematica can't decide whether to round up or down--it SHOULD apply round-to-even, to give zero, but it's trying to do this with just numerical values. As I recall, deciding when A == B is a profoundly difficult problem. I'm not sure how else one could go about this. (Oh, sure, the immediate problem could be fixed by applying a special rule for logarithms, but what about special functions for which the relations are still undiscovered?) --Ron Bruck