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From: aminer on 13 Apr 2010 15:54

Hello,


I have just updated parallel quicksort , now you can parallel
quicksort
on 'many' cores - not just two cores - look at the new program
pqsort2.pas inside the zip

Next step i will convert pqsort2.pas program to a unit that you can
import...

I am using inside pqsort2.pas the following functions:
QSortStr() , QuickSrtInt() and Merge()

Parallel quicksort version 1.01 quicksort many array parts - of your
array - in parallel using Quicksort, and after that it finally merge
them - with the merge() procedure -

And as you know , Quicksort is a divide and conquer algorithm that
have the following best case performance:

T(n) = T(n/2) + T(n/2) + (n)
= 2T(n/2) + (n)

And from case 2 of Master theorem, the recurrence equation gives:

T(n) = (n lg n)


Now, i have tested mergesort in parallel , but quicksort() gives
better
performance.


Note also that on Delphi parallel quicksort gave me 1.7x on two cores
- but with more optimization, delphi will give you better
scalability...- .

Freepascal on the other hand gave me just 1.2x on two cores, so,
FreePascal still have to be optimized on 'some' parts for better
parallel
computing...


You can download parallel quicksort from:

http://pages.videotron.com/aminer/


Sincerely
Amine Moulay Ramdane.

From: aminer on 13 Apr 2010 16:02

I wrote:
>And as you know , Quicksort is a divide and conquer algorithm that
>have the following best case performance:
>
>T(n) = T(n/2) + T(n/2) + (n)

I mean T(n) = T(n/2) + T(n/2) + O(n)

= 2T(n/2) + (n)


And from case 2 of Master theorem, the recurrence equation gives:


T(n) = (n lg n)

You can download parallel quicksort from:

http://pages.videotron.com/aminer/



Sincerely,
Amine Moulay Ramdane.

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