Oh, sorry, thinko: you wanted the first digit, and I gave you the last digit.
So:
[: +/@:({."1) 10 #.^:_1 p:@:i.
Or you could do something along the lines of:
+/@:(<.@:% >:@:<.&.(10&^.))@:p:@:i.
Of course, I haven't tested any of this, but the fact that I can respond in
such a manner from my blackberry, on my commute, without the aid of a J
interpreter, may tell you something about tacit programming.
In other words: using tacit code, we are communicating.
-Dan
PS: Of course, we could also communicate using explicit code or Fortran or
even standard math notation; it would just be harder to read & write under
these constraints.
For example, tacit's concise notation allows the reader to quickly spot the bug
in my initial suggestion (last digit vs first), and similarly allows the writer
to concisely express abstract concepts like &.(10&^.) .
(And elegantly, if I'm allowed to editorialize)
Please excuse typos; composed on a handheld device.
-----Original Message-----
From: Björn Helgason <gos...@gmail.com>
Sender: programming-boun...@jsoftware.com
Date: Tue, 16 Nov 2010 12:38:39
To: Programming forum<programming@jsoftware.com>
Reply-To: Programming forum <programming@jsoftware.com>
Subject: Re: [Jprogramming] tacit programming
That is not giving the correct answer 43 for the first 15 primes
(10 +/@:#: p:@:i.) 15
68
([: +/ [: > [: ".&.> [: [ [: {.&.> [: [ [: ":&.>@p: i.) 15
43
2010/11/16 Dan Bron <j...@bron.us>
> Björn wrote:
> > The objective is to get the first number from a list of primes.
> >
> > Is there a better way of getting the first number from a list of numbers
> > putting them each in a box than making it first a character and the
> taking
> > the first of each element making it a number and summing up the resulting
> > list?
>
> I've always preferred to ask for digits directly (numerically), rather than
> projecting into the string domain and returning to the numeric domain:
>
> 10 +/@:#: p:@:i.
>
> -Dan
>
>
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>
--
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Fornustekkum II
781 Hornafirði,
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http://groups.google.com/group/J-Programming
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