Wait, bad idea... that rot13 only works because 13 is a factor of 26.
Instead (and this is a fast bug fix, I have not thought much about
more elegant forms, though several paths for rephrasing come to mind):
rotN=: 1 :'{&((65 97 +/ m |. i.26) ((65 97 +/i.26)}) i.256)&.(a.&i.)'
--
Raul
On Fri, Dec 23, 2011 at 11:21 AM, Raul Miller <rauldmil...@gmail.com> wrote:
> Here's what I use for rot13:
>
> rot13=: {&((65 97+/~i.2 13) |.@[} i.256)&.(a.&i.)
>
> If I wanted to generalize that, I would probably go with:
>
> rotN=: 1 :'rot13=: {&((65 97+/~i.2,m) |.@[} i.256)&.(a.&i.)'
>
> 13 rotN 'testing'
> grfgvat
> 13 rotN rot13 'testing'
> testing
>
> --
> Raul
>
> On Fri, Dec 23, 2011 at 11:00 AM, Lorenzo Costanzia di Costigliole
> <lorenzo.costan...@gmail.com> wrote:
>> NB. What is the most elegant way to rotate uppercase
>> NB. and lowercase letters by n? ("rotation cipher")
>>
>> c2n=: a.&i.
>>
>> lc=: >&96 *. <&123
>> uc=: >&64 *. <& 91
>>
>> s=: 'Btggn Rwgxhibph 2011 id iwt Y-Egdvgpbbxcv bpxaxcv axhi!'
>>
>>
>>
>> NB. I came up with those, but I think there’s still room for improvement
>> NB. (Isn't there something in the J-Phrases?)
>>
>> NB. uppercase -> 2, lowercase -> 1, else -> 0
>> cl=: +:@uc + lc
>> cl`(] , ([: 26&| +&n)&.(-&97) ,: ([: 26&| +&n)&.(-&65))}&.c2n s
>>
>> ((] + ] ]`([: 26&| n + ])@.((0~:[)"0) [ - ]) (97&*@lc + 65&*@uc))&.c2n s
>>
>> NB. Enumerate all possibilities
>> |: ((] + ] (26 # ])`([: 26&| (i.26) + ])@.((0 ~: [)"0) [ - ]) (97&*@lc
>> + 65&*@uc))&.c2n s
>>
>> NB. Thanks!
>> ----------------------------------------------------------------------
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