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Subject: Re: Question about using Crafty to debug my program's perft

Author: Andreas Herrmann

Date: 07:04:50 07/17/03

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On July 17, 2003 at 09:55:43, Uri Blass wrote:

>On July 17, 2003 at 09:51:46, Andreas Herrmann wrote:
>
>>On July 17, 2003 at 02:26:19, Albert Bertilsson wrote:
>>
>>>A great way to find buggs in move generation is this:
>>>1. Have a command that instead of calculating perft calculates the perft values
>>>for all the children, and prints the list like this:
>>>b1c3 9755
>>>b1a3 8885
>>>g1h3 8881
>>>g1f3 9748
>>>a2a3 8457
>>>...
>>>2. Have a correct version of your program or another program that can do this
>>>too.
>>>3. When there is a difference at any perft value you see exactly which move that
>>>leads you closer to the bug, do the move and calculate the perft values with
>>>depth - 1, very soon you'll be at level 1 and when you compare the list of
>>>children you'll see which move is missing, or illegal.
>>>
>>>If you need an engine to compare with you can use Sharper, I call the command
>>>"divide".
>>>
>>>http://www.albert.nu/programs/sharper
>>>
>>>/Regards Albert
>>
>>Hi Albert,
>>
>>you can get the same results, if you do one possible move from starting position
>>and then start perft n-1. Just do this for every legal move from the starting
>>pos. and you have the same results. So you can compare it with each program,
>>which has perft implemented.
>>
>>Andreas
>
>Yes but doing this is a work and it may be better to have the list of moves and
>number in 2 windows so you can compare fatser to see the mistake in case that
>the numbers are different.
>
>doing and undoing all the legal moves and calculating perft  may take
>significant time and I say it from experience because I did it when movei had
>problems with perft.
>
>Uri
>Uri

off course. I just tryd to explain, how to compare the results with other
engines, that havn't implemneted it in that way.

Andreas





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