[plt-scheme] Re: please help with generating random permutation

From: Sigrid (keydana at gmx.de)
Date: Fri Sep 11 16:28:33 EDT 2009

Hi Will,

thanks a lot, this helped me very much (both in understanding and in
giving me the confidence to defend my code)!

> of the (many) properties that good generators have is that their  
> outputs after each call to (random) are statistically un-correlated.  
> In general, it is impossible to tell via statistical tests whether a  
> generator has been randomly re-seeded between outputs, or is  
> continuing the same stream of random numbers

This is what I did not understand before, I think I confused the
statistical distribution and the predictability here. But your
explanation makes it very clear!

  I usually re-seed the generator using code  
> like:
> (with-input-from-file "/dev/random"
>    (lambda ()

I will do that too, just "in case". But anyway, today I ran a test
again with a sample size of around 60, conveniently using crontab (and
so having independent runs, but with clearly different seeds) and the
result looked reassuring already :-)

Thanks again,

>  PGP.sig
> < 1 KBAnzeigenHerunterladen
> _________________________________________________
>   For list-related administrative tasks:
>  http://list.cs.brown.edu/mailman/listinfo/plt-scheme

Posted on the users mailing list.