It is embarrassing not to have seen the issue right off. Comparison tolerance or "fuzz" is quite useful. Yes, it does cause some problems like this, but I think it solves so many more problems than it creates. Should situations like this raise some form of error? I think not. It is up to us as programmers to be aware when we are in an area where we are bumping into some limits.
Putting this in NUVOC might be a good idea. It is a fun problem that should interest both newcomers and experienced users of J. It is too easy to forget about comparison tolerance. It might be good to summarize this thread to show how experienced users get misled on this type of problem, not just new users. Entertain the newbies. On Wed, Sep 13, 2017 at 3:34 PM, Raul Miller <[email protected]> wrote: > http://code.jsoftware.com/wiki/Vocabulary/numberco#dyadic > > where i says: > > 3. If y is not an integer, the fractional part is added to the > least-significant digit of the result. > > ? > > Or the other one, where it says: > > To be precise, the value passed to the next atom is (y-remainder)%x. > If the quotient was tolerantly close to an integer, the remainder will > be set to exactly 0, and a small non-integer part will be passed to > the next digit. > > ? > > But both of those describe procedure, and neither says what problem > this solves for residue. (Neither answers the "why" question.) > > Thanks, > > -- > Raul > > > On Wed, Sep 13, 2017 at 5:24 PM, Henry Rich <[email protected]> wrote: > > Look at NuVoc #: Details > > > > Henry Rich > > > > On Sep 13, 2017 16:29, "Raul Miller" <[email protected]> wrote: > > > > There's not. > > > > There are, however, references to use of comparison tolerance in floor. > > > > The interesting question is: why are we using tolerant floor in residue? > > > > Thanks, > > > > -- > > Raul > > > > > > On Wed, Sep 13, 2017 at 3:48 PM, Erling Hellenäs > > <[email protected]> wrote: > >> I looked briefly in those references. I don't see any statements about > the > >> use of comparison tolerance in Residue. /Erling > >> > >> On 2017-09-13 18:30, Raul Miller wrote: > >>> > >>> Tolerance is an ugly thing, I guess. > >>> > >>> http://code.jsoftware.com/wiki/Essays/Tolerant_Comparison > >>> > >>> Thanks, > >>> > >> > >> ---------------------------------------------------------------------- > >> For information about J forums see http://www.jsoftware.com/forums.htm > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
