Help please

[Richard Donovan]

I need a function to concatenate a series of digits.

I tried:

concat=:4 : 'x:". (":x),(":y)'"0

Try with first 11 primes:

concat/p:i.11

235711131719232931

NB. Looks good

NB. But...

concat/p:i.12

23571113171923292160

  concat/p:i.12x

23571113171923292160

NB. These fail

Thanks,

Richard

[Don Guinn]

This should work; however, it doesn't need the / or rank defined to 0. Don't know if you require them.

{{;":&.>y}}p:i.12

23571113171923293137

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[Henry Rich]

23571113171923293137  exceeds integer, add x

Henry Rich

[Mike Day]

As Henry says;  this minor change to your fn works for 12 primes:

      concat=:4 : 'x:". ''x'',~(":x),(":y)'"0

   concat/p:i.12. NB.  No need to extend the input type for these primes

23571113171923293137

OK?

Mike

Sent from my iPad

On 24 Jul 2025, at 18:09, Richard Donovan <rsdo...@hotmail.com> wrote:



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[Richard Donovan]

  concat/p:i.12x

23571113171923292160

NB. These fail

Hi Henry! I already tried adding x with no luck, as above

Thanks, Richard

---

From: fo...@jsoftware.com <fo...@jsoftware.com> on behalf of Henry Rich <henry...@gmail.com>
Sent: 24 July 2025 18:30
To: fo...@jsoftware.com <fo...@jsoftware.com>
Subject: Re: [Jforum] Help please

 

[Richard Donovan]

That did the trick! Thanks all

---

From: 'Mike Day' via forum <fo...@jsoftware.com>
Sent: 24 July 2025 18:34

To: fo...@jsoftware.com <fo...@jsoftware.com>
Subject: Re: [Jforum] Help please

[Michael Day]

... though I do rather prefer this variant inspired by Don Guinn's suggestion:

   concatx =: {{'x',~' ' -.~;y}}&.":
   concatx p:1000+i.10
7927793379377949795179637993800980118017

Don's suggested fn returns a string/literal,  but the under neatly returns 

the input to extended,  even though the input is integer. 

Cheers,

Mike

Virus-free.www.avast.com

[Devon McCormick]

Your numbers look like they start out concatenated but you appear to want to change their type.  Why not something like this:

   ' ' (([ -.~ [: ": ])"0 1) p:i.10
2357111317192329
   ' ' (([ -.~ [: ": ])"0 1) p:i.50
2357111317192329313741434753596167717379838997101103107109113127131137139149151157163167173179181191193197199211223227229
   

--

Devon McCormick

Flâneur

[Michael Day]

Well - Richard Donovan's original cri de coeur concerned
loss of precision of the output integer representation of the concatenation,  
not the literal.  He wants an integer scalar output for an integer vector input.
What's wrong with that requirement?
Thanks,
Mike

[Devon McCormick]

So something like this:

   ".'x',~' ' (([ -.~ [: ": ])"0 1) p:i.50
2357111317192329313741434753596167717379838997101103107109113127131137139149151157163167173179181191193197199211223227229
   ".'x',~' ' (([ -.~ [: ": ])"0 1) p:i.10
2357111317192329
   

?

[Michael Day]

Yes,  I think that also fits his requirements

M

[Don Guinn]

concat=:,&":

concat/p:i.20

235711131719232931374143475359616771

[Henry Rich]

Bravo. 

This appends on the left, which is not in place and thus has quadratic performance.  For long strings it's worthwhile to append on the right:

   ,~&":/@|. p: i. 20
235711131719232931374143475359616771

Henry Rich

[Don Guinn]

It wasn't originally stated that the result should be extended and not literal; however, this makes the result extended and keeps your suggestion linear.

>:('x',~,~)&.":/@|. p: i. 20

235711131719232931374143475359616772