Author: Pete Galati
Date: 13:44:56 01/15/01
Go up one level in this thread
On January 15, 2001 at 14:07:00, Thomas Mayer wrote: >Hi Pete, > > >> So instead of going back to Windows and fixing the >> problem, I got the Nunntest from a different computer and ran Comet on #10 >> for a >> few hours. On this one it went negative for a while, and then it went >> positive >> after that. Hmmmm... > >>12. -0.67 10999 1777802606 g2g3 b8d7 f1g2 a3a5 h2h3 f8e7 >>13? -0.81 13376 -2126666136 g2g3 f8e7 g5f6 e7f6 d4e6 f7e6 >>13. -0.78 25638 -34456580 f4f5 b8c6 f5e6 f7e6 d4c6 b7c6 >>13. -0.71 27082 197569083 g5f6 g7f6 b1b3 a3a5 f1e2 h8g8 > >That is quite usual... I think Uli uses like me and most of the others a 32 bit >long variable to store the nodes count... > >The range of a 32 bit variable is: >signed: -2147483648....2147483647 >unsigned: 0....4294967296 > >As you can see, Uli uses signed variable... After 2147483647 moves it will >overflow and go back to negativ number -2147483648... Then it will be increased >again up to 2147483647 and after that again overflow... This would involve some inconvenient math then for me to figure out how mant nodes it was really seeing, but it's really not a concern of mine, so I personally wouldn't do the math. I forgot about C's odd math & variables stuff, I haven't messed with it for a while. C's math was never fun to think about (for me). >I use unsigned which means that the effect occurs after 4294967296 moves, Quarks Does it use more memory using unsigned? >node counter returns then to 0... >Maybe funny in this case is that in those days where i486 or i386 were uses for >chess, in most cases that was no problem, but things have changed... Anyway - it >does not influent Comets strength in anyway - a solution is to use a double >variable for node counter, but that WILL influent Comets strength because it >will get a little bit slower... (Well, maybe about 0,00000001% ... :) I think I >have read somewhere that Dieter Buerssner has implemented a double variable in >his program... > >Greets, Thomas > >P.S.: Chess programming is also fighting for every tick... so we won't implement >thinks that lose 0,00000001% .... :)))) I missplaced my C books (buried them), a double can do really huge numbers, right? I don't think slowing down Comet is a good option. Personally, I'd rather just having it report the nodes incorrect rather than loose strength. Pete
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