[mercury-users] Converting time_t to int using common library?

Ralph Becket rafe at csse.unimelb.edu.au
Tue Feb 20 17:31:02 AEDT 2007


Mark Brown, Tuesday, 20 February 2007:
> On 15-Feb-2007, Ralph Becket <rafe at csse.unimelb.edu.au> wrote:
> > doug.auclair at logicaltypes.com, Wednesday, 14 February 2007:
> > > Great!  Thank you for the RNG.  Is it better than the "Mother of all
> > > RNG" supplied as module rnd in qcheck?
> > 
> > I have no idea,
> 
> The answer to this question is no.  Likewise, the Mersenne twister is not
> uniformly better than Tausworthe.
> 
> Check out <http://random.mat.sbg.ac.at/> for a whole lot of good stuff
> on RNGs.  In particular these quotes:
> 
> 	All random number generators have their weak points.
> 
> 	Every RNG has its deficiencies. No RNG is appropriate for all tasks.
> 
> This is why I've been objecting all along to the idea of putting "the best"
> RNG in the standard library, or of giving our endorsement to any particular
> implementation, or indeed of implying that there even exists such a thing
> as the best RNG.

I agree.

> > but this link
> > www.cs.dartmouth.edu/~akapadia/project2/node27.html
> 
> "Project 2"?  Are you citing someone's coursework?
> 
> > tests some RNGs and concludes that "The Tausworthe RNG... is the best
> > RNG amongst the RNGs that we tested."
> 
> Bzzzt!  No A+ for you.  Even their own tables point out that Tausworthe
> is worse than MT on at least two empirical tests.

I quoted (part of) their conclusion; I didn't make any great claims for
the reliability of the study!

-- Ralph
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