Author: Robert Hyatt
Date: 15:15:27 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. This will be fixed in the next version. Node counter is 64 bits. And all uses of it are also 64 bits... The only issue is going to be printing them out, which might take some minor source changes for windows. IE in GCC, %llu is the way to print an unsigned 64 bit int. I will have to research what is needed for MSVC and then the commercial compilers for the various unix platforms, since the %ll was not included in the ANSI standard.
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