I found the "insert" to be slightly confusing when simple use of "power"
works as well:
   (+:@<:)^:_7 ] 2    NB. x=# bridges, y=# cakes for Granny

Though this did make me wonder about negative powers, so I was amused by
this:
   +:^:_7]2



On Mon, Jun 9, 2014 at 2:33 PM, Dan Bron <[email protected]> wrote:

> The negative in my algorithm was to indicate "working backwards".
>
> That is, if I want to end up with 2 cakes after bridge 7, during which you
> gained 1 and lost x/2, what must x be? Given that, what must you have had
> before bridge 6? And so on.
>
> In other words, that expression was intended to be the J transliteration
> of "If you 'undo' 1+x%2 seven times, what do you start out with?".
>
> -Dan
>
> Please excuse typos; sent from a phone.
>
> > On Jun 9, 2014, at 2:25 PM, Raul Miller <[email protected]> wrote:
> >
> > For what it's worth, my algorithm came up with the same answer as Dan's
> for
> > the 7 bridge 2 cake case, but comes up with a different answer for the 1
> > bridge 3 case case:
> >   +:@<:^:7: 2
> >
> >   +:@<:^:1: 3
> >
> > --
> > Raul
> >
> >
> >
> >
> >> On Mon, Jun 9, 2014 at 2:06 PM, greg heil <[email protected]> wrote:
> >>
> >> Dan
> >>
> >>> Rounding amongst Trolls is pretty peculiar;) Say you wanted to give
> >> Granny 3 cakes and only had to cross one bridge ...  Your algorithm says
> >> you only need start with 2.5 cakes! (Kinda unhygienic on the offspring's
> >> part;-)
> >>
> >> greg
> >> ~krsnadas.org
> >> ----------------------------------------------------------------------
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> > ----------------------------------------------------------------------
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>



-- 
Devon McCormick, CFA
----------------------------------------------------------------------
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