J always executes _starting_ from right to left,
but when it encounters adverbs or conjunctions, it
binds to the left. Otherwise you need extra
brackets for them, eg instead of writing
1 2 3 +/ 1 2 3
you have to write
1 2 3 (+/) 1 2 3
in your example, if it changed to
]^:y 5 which means (]^:y) 5
then it runs ok.
Чт, 02 мар 2017, Linda A Alvord написал(а):
> Raul,
> This works, but I didn't expect that it would:
> |
> fibjb=: 13 :'}:(,[:+/ (_2&{.))^:y 1'
>
> If:
> y=:5
> y 5
> |syntax error
> | y 5
>
> When does J get executed from left to right, and when is it from right to
> left?
>
> Linda
>
> -----Original Message-----
> From: Programming [mailto:[email protected]] On Behalf
> Of Raul Miller
> Sent: Thursday, March 2, 2017 2:53 PM
> To: Programming forum
> Subject: Re: [Jprogramming] Explicit fib
>
> These are equivalent:
>
> (,+/ @(_2&{.))^:4(1)
> 1 1 2 3 5
> (,+/ @(_2&{.))(,+/ @(_2&{.))(,+/ @(_2&{.))(,+/ @(_2&{.))(1)
> 1 1 2 3 5
>
> In other words, (F)^:4 does F four times.
>
> Does this help?
>
> Thanks,
>
> --
> Raul
>
> On Thu, Mar 2, 2017 at 2:38 PM, Linda A Alvord <[email protected]>
> wrote:
> > Joe, this has taken me a while because I like to understand something, at
> > least a little bit, before I respond. I can't quite how this works.
> >
> > (,+/ @(_2&{.))^:14(1)
> > 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610
> >
> > You get an extra term, but I could define your verb.
> >
> > fibjb=: 13 :'}:(,[:+/ (_2&{.))^:y 1'
> > fibjb 14
> > 1 1 2 3 5 8 13 21 34 55 89 144 233 377
> >
> > But I wish I could understand how it works as it looks so simple.
> >
> > A tree didn't help much:
> >
> >
> > 5!:4 <'fibjb'
> > ┌─ 3
> > ── : ─┴─ ,:'}:(,[:+/ (_2&{.))^:y 1'
> >
> > Dissect seemed to withhold its secrets. SO it's up to you to help me.'
> >
> > load 'debug'
> > dissect 'fibjb 14'
> >
> > Thanks in advance. Linda
> >
> > -----Original Message-----
> > From: Programming [mailto:[email protected]] On
> > Behalf Of Joe Bogner
> > Sent: Monday, February 27, 2017 9:49 AM
> > To: [email protected]
> > Subject: Re: [Jprogramming] Explicit fib
> >
> > This is how I would approach it for young children -- attempting to
> > follow your english description
> >
> > fibJ =: 3 : 0
> >
> > firstLast =. 1
> > secondLast =. 0
> > total =. 1
> >
> > for_N. i. (y-1) do.
> >
> > term =. (firstLast + secondLast)
> > secondLast =. firstLast
> > firstLast =. term
> >
> > total =. total,term
> >
> > end.
> > total
> > )
> > fibJ 15
> > 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610
> >
> > The definition is simpler if you just want the Nth number
> >
> > fibJ =: 3 : 0
> >
> > firstLast =. 1
> > secondLast =. 0
> >
> > for_N. i. (y-1) do.
> >
> > term =. (firstLast + secondLast)
> > secondLast =. firstLast
> > firstLast =. term
> > end.
> > term
> > )
> > fibJ 15
> > 610
> >
> >
> >
> > On Mon, Feb 27, 2017 at 9:16 AM, David Lambert <[email protected]> wrote:
> >> fib3=: 13 :'}.1|.,''),(fib2 '',"_ 1":i.y,1'
> >>
> >> ". fib3 6
> >> 0 1 1 2 3 5
> >>
> >>
> >> Let's reorganize by grouping all the strings to increase the sentence
> >> legibility.
> >>
> >> '),(fib2 ' ,"_ 1 ": ,. i. 7
> >> ),(fib2 0
> >> ),(fib2 1
> >> ),(fib2 2
> >> ),(fib2 3
> >> ),(fib2 4
> >> ),(fib2 5
> >> ),(fib2 6
> >>
> >> From here ravel, rotate by one position, finally discard the extra comma.
> >>
> >>
> >> On 02/27/2017 07:00 AM, [email protected] wrote:
> >>>
> >>> Date: Mon, 27 Feb 2017 05:01:34 -0500
> >>> From: "Linda A Alvord"<[email protected]>
> >>> To:<[email protected]>
> >>> Subject: Re: [Jprogramming] Explicit fib
> >>> Message-ID: <000301d290e0$7ae35ac0$70aa1040$@net>
> >>> Content-Type: text/plain; charset="utf-8"
> >>>
> >>> I like fib2 and things were going well but I hit a snag:
> >>>
> >>> ]W=:*i.2 2
> >>> 0 1
> >>> 1 1
> >>> mp=:+/ . *
> >>> fib2=:3 : '{. W&mp^:y 0 1'
> >>> ". }:, (14 5$'(fib2'),"1 (' ',"1 ' ',"1 ":,.>:i.14),"1 '),'
> >>> 1 1 2 3 5 8 13 21 34 55 89 144 233 377
> >>> fib3=: 13 :' ". }:, ((y,5)$'(fib2'),"1 (' ',"1 ' ',"1
> >>> ":,.>:i.y),"1 '),''
> >>> |domain error: fib2
> >>> | {.W&mp ^:y 0 1
> >>> It doesn't like the fact that that the fib2 should still be just
> >>> letters.
> >>>
> >>> It was fun anyway. Linda
> >>
> >>
> >> ---------------------------------------------------------------------
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> >> http://www.jsoftware.com/forums.htm
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--
regards,
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