2016-10-27 8:31 GMT+02:00 Martin McClure <mar...@hand2mouse.com>: > I think roundTo: is OK. #round: is not, and should be deprecated (at least > for Floats). For Floats, the idea of rounding to a specific number of > decimal digits is a fantasy. Here's why: Floats cannot exactly represent > most common decimal fractions. For example: > > 0.1 -- not representable > > 0.2 -- not representable > > 0.3 -- not representable > > 0.4 -- not representable > > 0.5 -- hey, representable! > > 0.6 -- not representable > > 0.7 -- not representable > > 0.8 -- not representable > > 0.9 -- not representable > > 1.0 -- representable. > > *Printing* a Float to a specific rounded decimal format is a sensible > idea, and should be encouraged. But trying for a "rounded Float" *number* > just can't be done exactly (except by converting to a Fraction). > > Fractions can be rounded to exact decimal fractions, so something like > "myFraction roundTo: 1/100" makes sense. But the current implementation of > round: on Fraction that converts to a Float just gets you the misery > detailed above. > > > On 10/26/2016 01:00 PM, Nicolas Cellier wrote: > > I've put a single slice in the inbox for the 3 issues because they all are > related. > See slice comment: > > For Float, implement guard to prevent overflow (15471), and use exact > representation for intermediate results (asFraction) so as to avoid double > rounding problems (15473) > > > The double rounding problem is not the fundamental problem, the > fundamental problem is that what is desired does not exist, because Floats > cannot exactly represent most decimal fractions. So this can't really fix > it.
Exactly. Thank's for good explanation
