Author: Robert Hyatt
Date: 20:08:43 12/06/01
Go up one level in this thread
On December 06, 2001 at 22:51:48, Miguel A. Ballicora wrote: >On December 06, 2001 at 18:15:27, Robert Hyatt wrote: > >>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. > >What if you do not print nodes and you just print Mnodes or Knodes or Gnodes? >You caculate them the way you want and then make a division so it will >be a 32 bit int again but it will mean a different unit. >At that point, nobody will care if it is 8123234543 nodes or 8123234 Knodes. >This way is more user friendly and easier to port. > > >iguel x 1000000 (a.k.a Miguel) An unsigned int can go to 4 billion and change. that is 4 trillion nodes if converted to K nodes. Good hardware today can easily go 3-4M nodes per second. Say 4 to make it round. that means 1M seconds or 2 years. Safe for today probably. But the problem returns in a few years. But the reason I don't like Knodes is debugging. When I make a change to the search I want to see the _exact_ node count to be sure it doesn't change when it shouldn't. Knodes would hide that.
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