|Random numbers should not be generated with a method chosen at random.
| -- Donald E. Knuth
|The generation of random numbers is too important to be left to chance.
| -- Robert R. Coveyou, Oak Ridge National Laboratory, 1969
The Mersenne Twister Free Pascal uses is one of the best PRNGs known
today, it just has to be used the right way. But calling it from
several threads and "randomly" overwriting its state array is
definitely not the right way to use it.
I'm disappointed, because I compiled the following program (on linux):
rnd.pp
begin
Randomize;
writeln(random(394));
end.
and I ran it for 11 times, and the results are rather strange:
310.
198
344
322*
322*
317-
317-
192
336.
382.
339.
(upon noting the dups I had to re-run again twice, getting:)
120
297.
so, I've got two times a repetition, though I only re-ran the program.
(noted with * and - )
Then I made a new series of random generating:
297.
120
310.
382.
336.
192
317
322
344
198
339.
I only have two problems with these random numbers:
Firstly, I can notice a repetition of some "random" numbers (noted with
".")
Then also 70% of them are 3xx
I learnt about random numbers, that they do not behave by this way.
Anyway, random numbers are behaving randomly, and we also had a big
scandal about the national lottery, when (using mechanical methods),
the occurence of "47" was too frequent in the last ten years,
and also last year we had around 50% without winners :) (which added
hundreds of thousands of EURO to the company manager's salary)
So I am really happy with FPC, but this was a bit strange for me.
So it wasn't running simultaneously, but just executing the binary file by
hand one after another.
I also agree with you Vincent, random numbers must be taken extremly
carefully. But they also have to care for us :)
Actually I can't recall (though I studied it 10 years ago) which functions
should increase the entropy.
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