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.
----- 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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