C.!.2 (1 2 3)
0
C.!.2 (0 1 2)
1
Permutations are defined as rearrangements of i. n .
Why? I dunno... why not? It's a nice feature to have someplace, and C.
seems as good as any.
Henry Rich
On 10/4/2010 8:38 PM, Marshall Lochbaum wrote:
> Is there any logical reason why C.!.2 gives parity? I had to look this up
> and as a result am skeptical...
> Also,<: seems unnecessary.
>
> Marshall
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Henry Rich
> Sent: Monday, October 04, 2010 8:14 PM
> To: Programming forum
> Subject: Re: [Jprogramming] Distinct Numbers in Rows and Columns
>
> I got to
>
> -.@(0&e.)@:(C.!.2)@(,|:)@:<:"2
>
> as the test for whether the item is a Latin square. I have been trying to
> find some cool test, without success.
>
> Henry Rich
>
> On 10/4/2010 7:37 PM, Roger Hui wrote:
>> Great minds think alike, eh? (But I think you need to test your
>> expressions ;-) Go to http://www.jsoftware.com/jwiki/Essays/KenKen
>> and look about a third of the way down,
>>
>> q #~ (8$15) -:"1 (+/"1 ,. +/"2) q{0,2^i.4
>>
>> The initial effort in your previous msg is also similar to my initial
>> effort.
>>
>>
>>
>> ----- Original Message -----
>> From: Marshall Lochbaum<[email protected]>
>> Date: Monday, October 4, 2010 16:28
>> Subject: Re: [Jprogramming] Distinct Numbers in Rows and Columns
>> To: 'Programming forum'<[email protected]>
>>
>>> Here's a funny--and much faster--one:
>>> p=.p:i.n
>>> *./"1 (*/p) = (*/"2 ,. */"1) q{p
>>>
>>> Actually, I suppose it is better to do it with addition, so p=.2^i.n
>>> *./"1 (+/p) = (+/"2 ,. +/"1) q{p
>>>
>>> Marshall
>>>
>>> -----Original Message-----
>>> From: [email protected]
>>> [mailto:[email protected]] On Behalf Of Roger Hui
>>> Sent: Monday, October 04, 2010 6:41 PM
>>> To: Programming forum
>>> Subject: [Jprogramming] Distinct Numbers in Rows and Columns
>>>
>>> An interesting puzzle arising from the KenKen solver:
>>> q is an array with shape (m,n,n) and (,q) e. 1+i.n .
>>> Which items of q have 1+i.n in each row and in each column?
>> ----------------------------------------------------------------------
>> For information about J forums see http://www.jsoftware.com/forums.htm
>>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
