It is odd, though, that even with comparison tolerance set to zero, +.
is not associative on fractional floating point values:
9!:19]0
0j16":,.+./4.57 4.34 4.44
0.0000000000000036
0j16":,.+./|.4.57 4.34 4.44
0.0000000000290870
It is commutative though:
(-:|:)+./@>{;~4.57 4.34 4.44
1
0j16":+./@>{;~4.57 4.34 4.44
4.5700000000000003 0.0100000000000655 0.0099999999999758
0.0100000000000655 4.3399999999999999 0.0200000000000466
0.0099999999999758 0.0200000000000466 4.4400000000000004
I'm not quite sure what's going on here... maybe a built in epsilon
which is independent of comparison tolerance?
Thanks,
--
Raul
On Fri, May 15, 2020 at 6:53 PM Hauke Rehr <[email protected]> wrote:
>
> In case you are willing to accept labelling it a problem.
>
> As I mentioned by altering the thread’s subject, yes,
> this ain’t a bug. But there may be an opportunity for
> improvement without sacrifice. Or so do I think.
>
>
> Am 16.05.20 um 00:49 schrieb 'Michael Day' via Programming:
> > Not a new "bug" - I've still got J503 for some reason - so:
> >
> > +./4.57 4.34 4.44
> > 5.39568e_12
> >
> > ABOUTJ_jijs_ NB. nearest thing to JVERSION???
> > Copyright 1994-2004 Jsoftware Inc.
> > For information about this and related products:
> >
> > Jsoftware Inc.
> > P.O. Box 330
> > Excelsior, MN 55331
> > tel: 952 470-7345 fax: 952 470-9202
> > www.jsoftware.com
> > [email protected]
> >
> > As Devon and Henry suggest, it's the usual problem with "exact"
> > representation of reals.
> >
> > Mike
> >
> >
> >
> > On 15/05/2020 15:17, 'Bo Jacoby' via Programming wrote:
> >> +./4.57 4.34 4.44
> >> 5.39568e_12
> >>
> >> NB. this was not the correct answer. A bug?
> >>
> >> +./x:4.57 4.34 4.44
> >>
> >> 1r100
> >>
> >> NB. this was a work-around
> >> Thanks!
> >> Bo.
> >>
> >>
> >>
> >>
> >> ----------------------------------------------------------------------
> >> For information about J forums see http://www.jsoftware.com/forums.htm
> >
>
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