The dictionary entry says:
In general, if y is not an atom, x may be a list of length not more than
$$y , and if y is an atom, it is replaced by ((#x)$1)$y . Element k
produces (k{x){."(($$y)-k) y ; an infinite value is replaced by the length
of the corresponding axis.
The statement is correct, both formally (executes on a computer) and
informally, if it says $$y or #$y. If it is correct, then it is not a
mistake. It is not to say that # and $ are interchangeable in all
situations.
On Sat, Oct 5, 2013 at 6:13 PM, Ganesh Rapolu <[email protected]> wrote:
> Brevity is not always conducive to understanding. I would be grateful if
> you gave an explanation
> as to why this flexibility in the rank of a length is not a mistake.
>
>
> On Sat, Oct 5, 2013 at 3:01 PM, Roger Hui <[email protected]>
> wrote:
>
> > If it is a mistake I'd correct it, but it's not a mistake.
> >
> >
> > On Sat, Oct 5, 2013 at 5:44 PM, Ganesh Rapolu <[email protected]>
> wrote:
> >
> > > I am having difficulty finding reasons other than tradition that a
> length
> > > should be allowed to be a list.
> > >
> > > badlength =. $
> > > mean =. +/ % badlength
> > > $ mean"1 i. 5 5
> > > 5 1
> > >
> > > Of course, J already does the right thing by providing # . It might be
> in
> > > the spirit of J to continue to correct mistakes made in APL by
> correcting
> > > the documentation for take.
> > >
> > >
> > > On Sat, Oct 5, 2013 at 2:19 PM, Roger Hui <[email protected]>
> > > wrote:
> > >
> > > > It is traditional in APL (and APL-like) systems that a length is a
> list
> > > or
> > > > a scalar.
> > > >
> > > >
> > > >
> > > > On Sat, Oct 5, 2013 at 4:53 PM, Ganesh Rapolu <[email protected]>
> > > wrote:
> > > >
> > > > > Although it is the case that for a verb v and integer k, v"k and
> v"(,
> > > k)
> > > > > are the same, it might be confusing if the length referred to in
> the
> > > > phrase
> > > > > 'x may be a list of length not more than $$y' is not a scalar.
> > > > >
> > > > >
> > > > > On Sat, Oct 5, 2013 at 1:36 PM, Roger Hui <
> [email protected]
> > >
> > > > > wrote:
> > > > >
> > > > > > Both $$y or #$y are correct in this case.
> > > > > >
> > > > > >
> > > > > >
> > > > > > On Sat, Oct 5, 2013 at 4:14 PM, Ganesh Rapolu <
> [email protected]
> > >
> > > > > wrote:
> > > > > >
> > > > > > > In the last paragraph, $$y should be #$y.
> > > > > > >
> > > >
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