[Scottish] allowing a large newborn sea-mammal to collide with a rocky plane toid object devoid of atmosphere somewhere in another galaxy

Allan Whiteford scottish at mailman.lug.org.uk
Fri Mar 21 09:37:01 2003


> On Fri, 2003-03-21 at 09:06, John Hallam wrote:
>> On Thu, 20 Mar 2003, Huard, Elise - D C&W Consultant wrote:
>>
>> > Or to phrase it differently : i need a random number generator that
>> won't give the same sequence of numbers every time that the seed is
>> reinitialised in the same second (by 2 different users)
>> > srand(time(NULL))
>> > and then rand()
>> > doesn't work.
>> > Or a different kind of seed ?  Suggestions are welcome (should be
>> readily available in your standard Unix system)
>>
>> 	One thing you can do is to execute `ps' and hash the output, e.g.
>> with MD5, and use some of those bits as your seed.  There is enough
>> going on in a PS output to make duplicate seeds rather unlikely,
>> unless (perhaps) you have a multiple CPU machine which can execute
>> multiple ps invocations simultaneously...
>>
>> 	As someone else said, be careful with rand() if you want good
>> random sequences -- some rand()s are seriously broken.  A good cheap
>> random number generator is the Mersenne Twister, which you can find at
>> http://www.math.keio.ac.jp/~matumoto/emt.html
>>
>> 	John.
>
> A white noise source connected to the sound card input would be a good
> truly random number generator.
>
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Now all we need to be able to do is create a true white noise source.
Probably the best way to achieve this is to get a computer with a good
software random number generator to produce random numbers and output them
from a soundcard :).

Thanks,

Allan