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

From: Larry Evans (cppljevans_at_[hidden])
Date: 2005-07-26 11:23:59

On 07/26/2005 10:39 AM, David Abrahams wrote:
> Larry Evans <cppljevans_at_[hidden]> writes:
> 
> 
>>On 07/26/2005 07:25 AM, David Abrahams wrote:
>>
>>>Alex Mendes da Costa <alexmdac_at_[hidden]> writes:
>>>
>>>
>>>
>>>>The iterator that I am proposing would provide the sequence (1,10),
>>>>(2,10), (1,20), (2,20).
>>>
>>>
>>>Oh, you want a cross-product iterator.  Interesting idea.
>>>
>>
>>BTW, the J or apl term for this would be "outer-product"
>>(produced with '/' operator) applied to the "append" operator
>>(','):
>>
>>   ,/
>>
> 
> 
> Wow, I'm impressed.  I usedta know APL inside-out, but it's been 25
> years.  But that's just an ASCII translation of the real symbol, no?
> 
No, actually J is an ascii translation of apl.  I should have been
clearer ;(  I originally started to use apl and %o% to "represent" the
'jot' apl symbol, but I figured referring to J with it's ascii
characters would be easier and *hopefully* easier to read.  Anyway, in
apl, it would be:

      S1 %o%., S2

where, as mentioned, %o% represents to apl 'jot' symbol.

The following is another reference to "outer-product" (and also
where I got the idea to use %o%):

   http://www.math.unm.edu/splus/node37.html