Re: [boost] Proposed addition to the iterator library for iterating over all tuples.

From: Larry Evans (cppljevans_at_[hidden])
Date: 2005-07-26 13:24:00

On 07/26/2005 09:39 AM, Larry Evans wrote:
[snip]
> IOW:
> 
>    1 2 ,/ 10 20
> 
> produces:
> 
>    1 10
>    2 10
>    1 20
>    2 20
> 
Actually, it produces

    1 2 10 20

To get nearly what Alex wants, the following seems to work:

<--------- cut here ---------
r=: x ,"0/ y
    r
1 10
1 20

2 10
2 20

3 10
3 20
    x
1 2 3
    y
10 20
    $r
3 2 2
 >--------- cut here ---------
IOW, the result, r, is a 3 by 2 by 2 multi-dimensional array.
I got this by downloading the J code as described here:

   http://www.jsoftware.com/download_systems.htm

and executing:

   jconsole

and then simply trial-and-errored and reread:

   http://www.jsoftware.com/books/pdf/brief.pdf

many times until I got something to work.  The ,"0
causes , to be applied on rank 0 cells of the data
(according to p. 16 of brief.pdf).