Puzzled about random initialisation
Robin Becker
robin at SPAMREMOVEjessikat.fsnet.co.uk
Thu Jul 8 15:05:51 EDT 2004
Paul Rubin wrote:
> Robin Becker <robin at reportlab.com> writes:
>
>>I get dirrent draws for each run even when the system time doessn't
>>differ bu much. I'm puzzled exactly how the random generator is being
>>initialised.
>
>
> The rng has complicated internal state that's initialized completely
> different if the seeds are even slightly different. If you want to
> study the algorithm, google on "mersenne twister". The random module
> is not random enough for the most demanding applications, particularly
> those where someone who has studied the algorithm might be trying to
> predict the output, for example online games being played for large
> real prizes. But it should be good enough for most stuff like
> physical simulations.
I'm not sure that answers my question. The seed in question is supposed
to be determinate.
The docs say system time is used as an initial seed and my reading of
the code seems to suggest that the actual input is a single time_t value
which apparently changes once per second.
Observation suggests that we don't get the same value even when separate
python processes start in the same system time second. So my
understanding is flawed.
However, I would still like to know how random starting a python process
and taking a single randint value is? Can someone clever guess what
values will be thrown up in a specified system time second?
--
Robin Becker
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