" &. " - often called "under" - is a conjunction: it combines two verbs,
applies them to the arguments, then applies the inverse of the second verb
to the result. I mostly use this with the second verb " > " ("open" or
"unbox"), as Raul did here, to apply the first verb to things inside boxes
then box the results.
So, in your case, the first verb " ": " turns each number into a character
string and boxes each one; in this case, the initial "open" is a no-op
because the items were not boxed.
"Under" has a sister " & " ("bond") which does the same thing but without
applying the inverse of the second verb.
Another example of "under" is this example:
1 2 3 +&.^. 4 5 6
4 10 18
This takes the logs of both arguments, adds them, then anti-logs the result;
since adding logarithms is the same as multiplication, this is what it
does. Compare this to "bond" (without the dot):
1 2 3 +&^. 4 5 6
1.3862944 2.3025851 2.8903718
which leaves the logarithms alone after it's added them.
On Thu, Sep 8, 2011 at 12:21 PM, David Vaughan <[email protected]
> wrote:
> Thanks.
>
> Could you explain how the ":&.> part works please? I don't really
> understand &. from the vocabulary section.
>
> ___________________________
>
> David Vaughan
>
> On 8 Sep 2011, at 16:54, Raul Miller <[email protected]> wrote:
>
> > On Thu, Sep 8, 2011 at 11:42 AM, David Vaughan
> > <[email protected]> wrote:
> >> 1":>:i.20
> >> 123456789***********
> >>
> >> But I want it to look like: 1234567891011121314151617181920
> >
> > ;":&.>1+i.20
> > 1234567891011121314151617181920
> >
> > --
> > Raul
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
--
Devon McCormick, CFA
^me^ at acm.
org is my
preferred e-mail
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