Author: Miguel A. Ballicora
Date: 15:13:55 12/06/01
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On December 06, 2001 at 17:02:42, Slater Wold wrote: >On December 06, 2001 at 15:21:17, J. Wesley Cleveland wrote: > >>This problem is like the problem "How many people does it take before >>it is probable that two have the same birthday ?". The answer, which >>many people find suprising is 23. To calculate this, calculate the >>probability p, that two people have different birthdays = 364/365. >>Then calculate how many pairs of people n, you need before this is less >>than 1/2, p^n <.5. Then find the number of people g, which taken two at >>a time is >= n, g = n*(n-1)/2. >> >>The same method tells you how many different positions you can have >>before it is likely that two will have the same hash key. >> >>32 bits 77163 >>48 bits 1.97536627683E+7 >>64 bits 5.05693754118E+9 >> >> >>Thanks to Cliff Leitch for providing a high precision freeware calculator. > >I agree. It's time for 64 bits and integers. > >On Crafty right now, I cannot search for more than about 6 minutes a position, >or the node counter resets. That's a bummer. You don't need 64 bits to keep track of the nodes (since it is number that increases one by one). It is just that the programmers prefer it in this way, I guess, to save a tiny bit of speed 0.01% maybe?. I agree with you, this should be taken care. It is annoying for people like you that analyzes for a long time on fast processors. Miguel
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