Re: Am I misunderstanding random numbers?

[Christopher Eykamp <chris@...>]

I'm running on Windows, embedded in a C++ app.  The chances of a re-seed 
seem minimal, as the two lines I posted are executed one after the other 
in the same file.

I have temporarily resolved my problem by overwriting the random 
function to call my C++ program and use it's random function, which 
seems to be... well... random.

If the seeds were the same, I would expect the results I see, but 
they're clearly different.

Chris

PS I read the article on LCGs, and I assume this to mean that Lua uses 
one of these.  I didn't see much in there that would explain why 
different seeds would end up producing similar streams of random numbers.


On 3/16/2010 3:17 AM, Javier Guerra Giraldez wrote:
> On Tue, Mar 16, 2010 at 3:54 AM, Christopher Eykamp<chris@eykamp.com>  wrote:
>    
> > When I run the following snippet, I get unexpected results.  About 50% of
> > the results are the same (I've omitted the different ones from my results
> > list, because they're not as interesting :-)
> >
> >
> > math.randomseed( __randomSeed )
> > print ("Seed: ".. __randomSeed,
> > math.random(10000),math.random(10000),math.random(10000),math.random(10000))
> >      
> are you sure the RNG isn't 'reseeded' before the call to print() ?
> what platform are you using?
>
> on two _very_ different platforms (a kubuntu Linux x86_64 and an
> embedded MIPS box) i get consistent results with same seeds, but not
> the values you're seeing there.
>
>
>