Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: How do you insure that Hash Table entries are correct?

Author: Robert Hyatt

Date: 20:54:19 09/16/00

Go up one level in this thread


On September 16, 2000 at 22:40:05, Larry Griffiths wrote:

>On September 16, 2000 at 19:25:56, Robert Hyatt wrote:
>
>>
>>This last thing suggests that maybe your hash keys are not as random as they
>>should be.  I have done some hash testing and I don't see any "holes".  IE I
>>can quickly write over nearly *every* position.  I detect this by simply running
>>a search, then counting how many entries are from this search, vs previous
>>searches.  I can get 99% easily...
>
>I did some testing and I believe you are correct, Bob.
>
>I changed the following in my code...
>
>//					hrandom=random(HASHTABLEENTRIES);
>					hrandom=random(4000000000);
>
>I dont know why I was using HASHTABLEENTRIES (the number of) as my
>input to random, but changing it to 4000000000 made the bands go away.
>
>Thanks Bob :)
>
>Larry.

what random() function are you using?   IE stock random() doesn't have any
arguments.  If it is a seed, there are known good and bad seeds.  In almost
_all_ cases, you want the seed to be odd, and usually prime.



This page took 0.01 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.