Author: Tom Likens
Date: 06:56:39 05/30/04
Go up one level in this thread
On May 30, 2004 at 06:44:55, Uri Blass wrote:
>I have the following function to initialize my random numbers
>
>typedef unsigned __int64 BitBoard;
>
>BitBoard rand64()
>{
> __int64 r = rand();
> r ^= (__int64)rand() << 15;
> r ^= (__int64)rand() << 30;
> r ^= (__int64)rand() << 45;
> r ^= (__int64)rand() << 60;
> return r;
>}
>
>void initializezobarray()
>{
> //starting zobrist keys
> char zobnum[128];
> int fil,i,j;
> srand(0);
> for (fil=0;fil<6;fil++)
> for (i=0;i<2;i++)
> for (j=0;j<64;j++)
> zobrist[fil][i][j]=rand64();
>
>
>}
>
>My first question is if I can be sure that I will get the same random numbers in
>every computer(I get the same in my computer but if I do not get the same in
>every computer than I may consider to rewrite it because I plan to use hash keys
>for my book and I do not want to have a problem that the program will not be
>able to use my book in another computer).
>
>I also see that Crafty is using a table of random numbers from a book and does
>not trust rand()
>
>My second question is if there is an advantage in doing it.
>
>Uri
Hey Uri,
The big advantage I've found from maintaining an internal table of random
numbers is that I don't have to worry about the opening book (and now
position and book learning) not working from compiler to compiler or even
OS to OS. The program is able to read its opening book regardless if I'm
running a Linux version, Windows version etc. It's just one less thing
to worry about, which is always nice.
And of course, if you want to start playing with the Hamming distance
it's easy. Of course, there is no real consensus (as far as I can tell)
on wheter numbers with a larger Hamming distance are better or not- so,
as always you should experiment and see what works best for movei.
regards,
--tom
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