Author: Uri Blass
Date: 04:25:09 05/30/04
Go up one level in this thread
On May 30, 2004 at 07:11:11, Tord Romstad wrote:
>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()
>
>If you use exactly the same executable on different computers, you will probably
>get the same random numbers every time. But if you compile with a different
>compiler, you will almost certainly get different random numbers. In other
>words,
>you will have to build your book again if you ever change your compiler.
>
>>My second question is if there is an advantage in doing it.
>
>Yes. The rand() function gives very low-quality random numbers.
Based on what experience?
I am interested only in the chess question and not if the number are random.
How much speed improvement people can get by changing the random number from
something like I do to better quality random numbers?
I consider to copy all the numbers to a text file and give the user the
possibility to change them.
Uri
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