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Subject: Re: Chess program improvement project (copy at Winboard::Programming)

Author: Stuart Cracraft

Date: 11:22:33 03/08/06

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On March 08, 2006 at 13:52:13, Gerd Isenberg wrote:

>On March 08, 2006 at 01:24:31, Gerd Isenberg wrote:
>
>><snip>
>>>>>>your eval or other odd things like that).
>>>>>
>>>>>** I do use floating point for the evaluation. This is a relic of something
>>>>>** that can be pulled out of the program if it is a really bad thing. Bob
>>>>>** has said it is due to floating points always being off.
>>>>>
>>>>
>>>>Floats just for eval or also all bounds and scores backed up to the root?
>>>>SSE floats or doubles under w64 are quite efficient, for instance you (or your
>>>>compiler) can work with vectors of four floats per instruction.
>>>>Is your nullwindow {alfa, alfa+1.0} or something like {alfa, alfa+1.0e-10}?
>>>
>>>They're all doubles and for everything that would normally be an int.
>>>
>>>This is handled with a typedef and could fairly easily be an int with
>>>some additional ifdefd code for %d as opposed to %f.
>>>
>>>My null window is always -alpha-1,-alpha.
>>>
>>
>>while 1 is the smallest int greater zero, i wonder with float or doubles whether
>>there is no "smaller" null window dependent on a possible fractional part of
>>your evaluation. Did you try -alpha-epsilon,-alpha for null windows with epsilon
>>far less one?
>
>In PVS with null windows - if no cut occurs - you don't improve alfa.
>This is obviously not the case if your alfa is let say 10.0 and beta 11.0 and
>your score is 10.1 or 10.9999.
>
>>
>>>If you think double is severely affecting reproducibility or putting
>>>bugs in that could cause a performance-hurting issue, I can make it
>>>int.
>>>
>>>Stuart

Thanks - I will test it with int instead of double by changing the typedef.
The compile worked but debugging will be required.



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