Not J as such, but one might consider including 2 & 5, which are also
"upside-downable"-ish, partly depending on the font.
Have you considered a constructive approach?
Eg take any number with only u-d digits possibly starting 0 in but not ending
in 0;
prepend the rotations of the reverse of all its digits or of all but the first.
Say, 016: prepend 910 for 910016 or 91 for 91016.
Any use?
Mike
Sent from my iPad
> On 26 Aug 2023, at 15:43, Richard Donovan <rsdono...@hotmail.com> wrote:
>
> Thanks Pascal, Raul et al
>
> For context, a friend just celebrated his 69th birthday and I noted this age
> reads the same either way up. For practice i wanted to write a J function
> that outputs all such possible numbers!
>
> I am starting by finding all candidate numbers (those having only digits 0 1
> 6 8 9, (I'm assuming 1 is upside-downable, even though when typed it isn't!).
> The next steps will be (1) to swap 6s with 9s and v.v. , then (2) reverse the
> digits and compare for equality.
>
> So using the supplied algorithm, i can now perform the first step as follows:
>
> seli=: 1 : 'u # ]'
>
> 5 20 $ 0 1 6 8 9 (*./@:(e.~)&~.&(/:~) 10&#. inv)("1 0) seli i.1000
>
> 0 1 6 8 9 10 11 16 18 19 60 61 66 68 69 80 81 86 88 89
>
> 90 91 96 98 99 100 101 106 108 109 110 111 116 118 119 160 161 166 168 169
>
> 180 181 186 188 189 190 191 196 198 199 600 601 606 608 609 610 611 616 618
> 619
>
> 660 661 666 668 669 680 681 686 688 689 690 691 696 698 699 800 801 806 808
> 809
>
> 810 811 816 818 819 860 861 866 868 869 880 881 886 888 889 890 891 896 898
> 899..
>
>
> That is step 0. I can now try to add steps 1 and 2!
>
>
> Sorry to be so frivolous but it helps me learn!
>
> [I just noticed I also need to remove all found numbers ending with zero!]
>
> Cheers,
>
> Richard
> ________________________________
> From: Programming <programming-boun...@forums.jsoftware.com> on behalf of
> Raul Miller <rauldmil...@gmail.com>
> Sent: 26 August 2023 13:46
> To: programm...@jsoftware.com <programm...@jsoftware.com>
> Subject: Re: [Jprogramming] integers occur in integers?
>
> Yes... using rank 1 0 on the implementation is a good alternative to
> boxing. Using the approach I had come up with (I have not done any
> benchmarking here), this could be:
>
> 3 2 1((0 = #@-.~) 10&#. inv)("1 0) 230 123 111 123123132
> 0 1 1 1
>
> --
> Raul
>
>> On Sat, Aug 26, 2023 at 8:30 AM 'Pascal Jasmin' via Programming
>> <programm...@jsoftware.com> wrote:
>>
>>
>> 3 2 1(*./@:(e.~)&~.&(/:~) 10&#. inv)("1 0) 230 123 111 123123132
>>
>> 0 1 1 1
>>
>>
>> On Saturday, August 26, 2023 at 06:31:01 a.m. EDT, Richard Donovan
>> <rsdono...@hotmail.com> wrote:
>>
>> I am trying to find out whether a series of integers y only contain a set of
>> integers x
>>
>> That is, 1 3 5 verb 5311 10531 536 1111111
>> should return 1 0 1 1
>>
>> NB. only 1 3 5 occur in 5311
>> NB. not only 1 3 5 occur in 10531
>> NB. not only 1 3 5 occur in 536
>> NB. only 1 3 5 occur in 1111111
>>
>> NB. x only contains digits 0-9 without repeat. #x is max 10
>> NB. leading zeros should be ignored in elements of y. No max for #y
>>
>> I have tried several methods using combinations of e. i. under< etc. but
>> haven't yet found a succinct verb that achieves what I want.
>>
>> I hope my description is clear
>>
>> Help gratefully received!
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