Author: Robert Hyatt
Date: 13:38:07 10/25/99
Go up one level in this thread
On October 25, 1999 at 16:05:20, Michel Langeveld wrote:
>On October 25, 1999 at 14:48:54, Dann Corbit wrote:
>
>>On October 25, 1999 at 12:26:37, Michel Langeveld wrote:
>>>On October 25, 1999 at 10:17:53, Dann Corbit wrote:
>>>>On October 23, 1999 at 10:36:40, Robert Hyatt wrote:
>>>>
>>>>>On October 22, 1999 at 10:03:29, Dann Corbit wrote:
>>>>>
>>>>>>Change to binary insertion and you will see a much bigger benefit.
>>>>>
>>>>>I tried both (from Knuth Sorting and Searching). Binary is very bad for
>>>>>lists that have 1-5 entries max. from testing on my machine. Simple
>>>>>insertion is no faster than the bubble sort I used, but it also turns out
>>>>>to be no slower either, after testing Crafty over 300 different positions.
>>>>>
>>>>>I think I'll leave insertion in, to prevent such discussions in the
>>>>>future, however. :)
>>>>I have found a new modification to insertion sort (binary or linear) that will
>>>>make a large improvement in speed. It has to do with the data movements to
>>>>perform the actual insertion. By delaying the insertion, I can do all data
>>>>movements as a single permutation and never move any element more than once. It
>>>>won't work for big lists though, since the code size is O(n!). With just ten
>>>>items there are a million leaves in the tree. However, for very small sublists
>>>>I think it will do very well.
>>>
>>>Best way to prove your statement is code it, and prove it's faster!
>>>Good news by the way.
>>Got the idea from a web page. Here is an example for n=3. Number of
>>comparisons is O(n*log(n)). For the left branch (1,2,3) do not move anything.
>>For (1,3,2) permute the 3 & 2. For (3,1,2) and (2,3,1) we must move all of
>>them, since none is in the right place, and for (3,2,1) we permute 1 & 3. It is
>>very simple, really. I have a code generator to write the output, but I think I
>>can simplify it a lot and use the inline keyword (it's C99). The colon in the
>>diagram means compare. We don't actually compare twice (e.g. if I test for 1 <
>>2 I do not have another test for 2<1 {because that only finds equal which is
>>unlikely and therefore a mostly wasted comparison}
>>
>> 1:2
>> / \
>> < / > \
>> / \
>> 2:3 1:3
>> / \ / \
>> < / > \ < / > \
>> / \ / \
>> 1,2,3 1:3 2,1,3 2:3
>> / \ / \
>> < / > \ < / > \
>> / \ / \
>> 1,3,2 3,1,2 2,3,1 3,2,1
>
>Seems to be an hardcoded sort and indeed worth trying!!
>Maybe writing it immediatly in assembly will gain an extra kind of speed.
>Did you btw. run an profile lately on the source of Crafty 16.19?
>I'm wondering which source has to be analyzed to gain an extra speed.
>
>MichelLangeveld
Evaluate() and its children use more CPU time than everything else put
together in normal positions. IE > 50% of total time is spent in the
various Evaluation() functions.
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