Re: random numbers

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

    Thanks all:

On 2025-09-15 11:18, Clinton Bunch wrote:

>       
>       Also note, RANDOM *isn't* random.  It's a
>         predictable, repeatable sequence of numbers that looks random. 
>         No computer produces truly random numbers.  In large part
>         because random is an analog function and computers are
>         inherently digital.  But some sources are better than others.  
>       
    Sure, I know we can never really 'get
      there' and I know there are other issues with zsh's RANDOM that
      are well accepted, but the above seemed a blatant lack of
      randomness. 
      
      Mark:
      
    > I
      mean, only if you use the whole value of RANDOM directly, which
      most applications of random numbers don't do. If you do the usual
      trick of taking the remainder of RANDOM modulo a range, e.g.
      picking random digits one at a time with (( RANDOM % 10 )), you
      won't see such a strong weighting. In the case of single digits
      you are 0.03% less likely to get an 8 or 9 than a 0 through 7, but
      that's a pretty mild deviation from uniformity. 
      
      Yeah, it's just that this Benford's Law thing only applies to the
      first digit in a set of random data, so the cure would obviate the
      point of the thing.  Anyway it seems that the law doesn't apply to
      RANDOM data anyway as I've since discovered -- I need to research
      the law a bit more.  I'm curious as to the '0.03%' that you
      mention, why is that?  Or is it to complicated to discuss here?  
      
      Ditto Roman's fix, it obviates the real issue which is limited to
      first digits.
      
      Lawrence:
      
    
> It would be goofy if the shell chose the range of RANDOM just to
eliminate bias with respect to base-10 leading digits.  One could
very well object that such a change would disrupt the current lack
of leading-digit bias for base-8 representations.

That's logical.  Ok then, I'm glad I asked.  

> A user who generates and uses random numbers needs to account for
bias.  This is not something the generator can do for you
    Right, forewarned is forearmed.  I was frankly expecting to hear
    that my view of randomness is a bit simplistic.   Anyway the result
    of the experiment is a failure in any case -- Benford's Law doesn't
    work here.