That was the Tcl example!  The Python example is just:

   encode 1 2 3 10 100 987654321x
828335141480036653618783

   decode 828335141480036653618783x
1 2 3 10 100 987654321

   (-: decode@:encode) 1 2 3 10 100 987654321x
1



On Fri, May 9, 2014 at 3:09 PM, Jose Mario Quintana <
[email protected]> wrote:

>
> I was not aware of this rosettacode task but by chance I was discussing
> this problem with Thomas a couple of days ago.  A classic answer, due to
> Gödel, is via the fundamental theorem of arithmetic but it is very
> inefficient.
>
>
>
> This is a slight variation of two verbs that I wrote some time ago:
>
>
>
>    ( encode=. 11&#.@:>@:(,&:>/)@:(<@:(10&,)@:(10&#.^:_1)"0)@:x: )
> 11&#.@:>@:(,&:>/)@:(<@:(10&,)@:(10&#.^:_1)"0)@:x:
>    ( decode=. 10&#.;._1@:(11&#.^:_1) )
> 10&#.;._1@:(11&#.^:_1)
>
>    NB. This is the Python example,
>
>    encode 1 2 3 10 100 987654321 135792468107264516704251 7x
> 10859468893418553562739357752202339093235635587121336
>
>    decode 10859468893418553562739357752202339093235635587121336x
> 1 2 3 10 100 987654321 135792468107264516704251 7
>
>    (-: decode@:encode) 1 2 3 10 100 987654321 135792468107264516704251 7x
> 1
>
>
>
> On Thu, May 8, 2014 at 7:38 PM, Raul Miller <[email protected]> wrote:
>
>>    A=: 1 2 3 10 100 987654321x
>>    B=: 1+{:A
>>    C=: B#.A
>>    B #.inv C
>> |nonce error
>> |   B    #.inv C
>>
>> Hypothetically speaking, we want something that can find A, given B and C.
>>
>> Perhaps
>>
>>    A-:((>.B^.C)#B)#:C
>> 1
>>
>> or
>>
>>    A-:B (((<.@%~,|){.),}.@])^:(<: {.)^:_ C
>> 1
>>
>> I ran into this while playing with
>> http://rosettacode.org/wiki/Index_finite_lists_of_positive_integers
>>
>> Currently, the J version is broken for the numeric list listed in the
>> python solution, and that's just silly. I could fix it easily enough,
>> but I've enough other things to do already.
>>
>> Thanks,
>>
>> --
>> Raul
>> ----------------------------------------------------------------------
>> For information about J forums see http://www.jsoftware.com/forums.htm
>>
>
>
----------------------------------------------------------------------
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