Thanks, that's helpful, although the tacit version of "bulk" is a bit
too much for me to parse.
I imagine factor of 2 helps because it gets you over the expected 6r5
rolls per "game", assuming I did that recurrence right
(e=(5r6*1)+1r6*(1+e)).
I do have some lingering style questions though:
1. It looks to me like David Lambert's solution used both (&>) and
(">) to force a verb to apply to the atoms, which I would write ("0).
Are there any particular reasons to prefer one over the other? ("0)
may require a ([) to avoid merging with a follow-up literal, (&>)
seems a little like exploiting a side-effect of (>), and (">) could
just as easily be ("+) or any other 0 0 0 verb.
2. Is there any difference between (bind) and (@:)? They look to me
like they would be identical.
Thanks,
Johann
On Thu, Sep 25, 2014 at 3:10 PM, Raul Miller <rauldmil...@gmail.com> wrote:
> That is very close to what I came up with, for the case where we want only
> a single value from our result:
>
> d6=:1 + ? bind 6
> repd6=: [:+/(,d6)^:(6={:)@d6
>
> Here's a variation on Roger Hui's approach, for the case where we want N
> values from our result:
>
> d6s=: 1 + [: ? #&6
> bulk=:{.#&0(],~(+/;.1~1:}:@,0~:6&|)@(],d6s@[))^:(0=6&|@{:@{.)^:_~]
>
> Example use:
> bulk 20
> 5 5 5 4 3 3 2 3 3 9 1 4 16 3 3 1 3 17 3 4
>
> This would probably be much clearer if implemented explicitly rather than
> tacitly, and probably would be more efficient also. So:
>
> bulkd6s=:3 :0
> r=. i. 0
> while. y >: #r do.
> r=. r, d6s y
> mask=. }: 1, 0~:6|r
> r=. mask +/;.1 r
> end.
> y{.r
> )
>
> But statistically speaking, this is still not as efficient as it could be.
> I think we'd do better with:
>
> bulkd6=:3 :0
> r=. i. 0
> while. y >: #r do.
> r=. r, d6s 2*y
> mask=. }: 1, 0~:6|r
> r=. mask +/;.1 r
> end.
> y{.r
> )
>
> Do you see why this tends to be more efficient?
>
> Thanks,
>
> --
> Raul
>
>
> On Thu, Sep 25, 2014 at 11:50 AM, 'Pascal Jasmin' via Programming <
> programm...@jsoftware.com> wrote:
>
>> this works
>>
>> (, >:@?@6:)^:((0=#) +. 6={:)^:_ i.0
>>
>> ([: +/ (, >:@?@6:)^:((0=#) +. 6={:)^:_) i.0
>> 11
>>
>>
>>
>> ----- Original Message -----
>> From: Johann Hibschman <jhibsch...@gmail.com>
>> To: Programming forum <programm...@jsoftware.com>
>> Cc:
>> Sent: Thursday, September 25, 2014 9:06 AM
>> Subject: [Jprogramming] Repeated rolling dice
>>
>> Hi all,
>>
>> For fun, I've been running some statistics for a game with an unusual
>> rule for rolling dice: if a 6 is rolled, roll again and add the
>> result, repeating on any subsequent 6s. I wanted to implement this in
>> J, collecting all the individual rolls (rather than just the sum.)
>>
>> It seems like there should be a more clever and elegant way to do
>> this, but this is what I have:
>>
>> NB. Simple roll.
>> roll0 =: >:@?
>>
>> NB. This seems to work, but it's not very clever.
>> roll =: 3 : 0
>> r =. >:?y
>> if. r=y do. r=. r,(roll y) end.
>> r
>> )
>>
>> NB. Attempt at iterating via power. Fails because repeats
>> NB. signal termination.
>> roll0^:(6&=)^:(<_) 6
>>
>> NB. Attempt at iterating via agenda. Not even close yet.
>> NB. ]`(]+$:) @. (=&6) NB. where to stick in the roll?
>>
>> This gives what I expect:
>>
>> roll"0 ] 10#6
>> 6 1 0
>> 3 0 0
>> 3 0 0
>> 2 0 0
>> 5 0 0
>> 2 0 0
>> 6 6 2
>> 2 0 0
>> 1 0 0
>> 6 3 0
>>
>> But is there a better way to do this? Also, are there any known issues
>> with the RNG? I've not gathered enough statistics to prove it, but the
>> results look clumpier (more identical values in a row) than I expect.
>> Now, I know that's a common cognitive bias, so it may just be me, but
>> is there a discussion of the quality of the RNG somewhere?
>>
>> Thanks,
>> Johann
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