Re: Why to call it pseudorandom?

From: Peter Webb (webbfamily_at_DIESPAMDIEoptusnet.com.au)
Date: 08/28/04 

Date: Sat, 28 Aug 2004 23:39:06 +1000

"David C. Ullrich" <ullrich@math.okstate.edu> wrote in message
news:hl11j09t9o6cd9tvc9a6o32se65hhlofkq@4ax.com...
> On 28 Aug 2004 05:55:20 -0700, luiroto@yahoo.com (Luis A. Rodriguez)
> wrote:
>
> >If an algorithm produces a infinte sequence of digits that never
> >falls into a loop and passes the most stringent statistical tests
> >about its uniformity, why to call it pseudorandom?
>
> maybe because the digits are not random? if they're produced by
> an algorithm then they're not unpredictable.
>
> >If genius discover a system of equations for the roulette, the
> >old "random" experiments made with roulettes will appear at daybreak
> >as pseudorandom?
>
>
> ************************
>
> David C. Ullrich
>
> sorry about the inelegant formatting - typing
> one-handed for a few weeks...

And at a practical level, all computer rand() generators loop. They take a
seed n and calculate f(n), then f(f(n)) etc.
So they loop over whatever range n can take (at most). If n is a 32 bit
integer - and it often is - it will loop over 4 billion numbers, probably
enough to generate enough mineseweeper boards and bridge hands to keep most
people happy.
Many rand() functions are however random according to all other statistical
criteria.

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