On May 6, 11:04 pm, Carl Witty <carl.wi...@gmail.com> wrote: > On Wed, May 6, 2009 at 1:46 PM, Yann <yannlaiglecha...@gmail.com> wrote: > >> In other words, > >> sage: RealIntervalField(4)(0, 1) > >> 1.? > >> prints as the interval [0 .. 2], rather than [-1 .. 1], because IMHO > >> it is useful to be able to know that an interval is nonnegative; and > >> we do this by always picking the result farther from zero whenever > >> there are two possible "correct" printings. (Note that 3.? and 4.? > >> would both include the interval [3.00 .. 3.25], so they are both > >> correct in that sense.) > > > I would agree if it was 4.?1 (even I find something like 4.?±1 easier > > to understand) > > but without the error explicitely written, I would prefer to do what > > is in the docstring: > > " In question style (the default), we print the "known correct" > > part of the number " > > My understanding of this sentence is that we print the digits known > > for sure. And if a > > number is in the interval [3.00 .. 3.25], this should be 3.? > > The design you decision si only relevant IMHO if the error digits are > > explicitely written > > We definitely don't want to print "the digits known for sure". > Consider the interval [0.999999 .. 1.000001], which would print as > 1.000000? with the current code (I'm ignoring the fact that the > endpoints are not exactly representable in binary). With printing > "the digits known for sure", the first digit that we know for sure is > the tens digit, which is known to be zero; that would give 0.?e1, > which gives vastly less information than 1.000000?. > > Perhaps the docstring you quote should be adjusted? Elsewhere (in the > module docstring) we find this variant: > > In question style, we print the "known correct" part of the number, > followed by a question mark. The question mark indicates that the > preceding digit is possibly wrong by +/- 1. > > Maybe that second sentence should be copied into the docstring for .str()? > > Carl
or print the error digit 4.?1 (expicit is better than implicit, etc :) ) --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
