On Tue, Sep 2, 2014 at 2:49 PM, 'Pascal Jasmin' via Programming <
[email protected]> wrote:
> Thomas,
>
> An interesting alternative to getting O. to apply to $: in quicksort,
> would be to apply your parallelism adverb to $:, which btw I am very much
> looking forward to release.
>
> quicksort=: (($:@(<#[), (=#[), $:@(>#[)) ({~ ?@#)) ^: (1<#)
>
> Appologies if you've already thought of the potential and it is just a bit
> trickier than just wishing it.
>
I hadn't thought of that Pascal, I will try it out when I get I chance. I
also want to try O. on the tail recursive version of quicksort. Ultimately,
my wish for O., though, would be to demonstrate it on problems where it can
be shown to have some advantage over existing solutions.
>
>
> ----- Original Message -----
> From: Thomas Costigliola <[email protected]>
> To: J Programming Forum <[email protected]>
> Cc:
> Sent: Thursday, August 28, 2014 9:27:39 PM
> Subject: Re: [Jprogramming] fit conjunction
>
> Henry, out of sheer curiosity, if you have a story of such evil follies I
> would be delighted to hear it. More seriously, do you have a tacit tail
> recursive verb for quicksort to share ? This is related to this post
> http://www.jsoftware.com/pipermail/programming/2014-August/039023.html
>
>
>
> On Thu, Aug 28, 2014 at 9:18 PM, Henry Rich <[email protected]> wrote:
>
> > On the contrary, stack depth is a killer for quicksort. In the worst
> > case, the stack depth is the number of items, as each partitioning gives
> a
> > partition of just one element. Tail recursion solves this problem.
> >
> > Not likely, you say? If your code is deployed somewhere important, Evil
> > People will send it an array that will produce a worst case.
> >
> > Perhaps you can use a random pivot... as long as the Evil People can't
> > guess your sequence.
> >
> > Henry Rich
> >
> >
> > On 8/28/2014 9:13 PM, Raul Miller wrote:
> >
> >> I guess I'd like to see your code to better understand how you are
> >> thinking.
> >>
> >> You might have a good point. You might be overlooking something. But I
> do
> >> not know yet.
> >>
> >> (This sounds fun, but stack depth is unlikely to be a problem for
> >> quicksort. Also, quicksort is often overkill and /:~ or bare /: are also
> >> worth considering.)
> >>
> >> Thanks,
> >>
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>
>
> >
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