In article <3e15944c$1@news.povray.org> , "George Pantazopoulos" 
<the### [at] attbicom*KILLSPAM*> wrote:

> I remember reading that the Mersenne Twister algorithm (and I think there
> are various improvements to it now) is supposed to be a very good, fast
> pseudorandom generator. Has anyone looked into it yet?

Well, finding a good random number algorithm isn't the main problem if one
ignores performance.  But performance is the main catch here!  And the
implementations I have seen clearly leads to terrible performance.
Completely unsuitable for the expected use:

After all the algorithms to be used have to compete against one single plain
memory access.  And an Mersenne Twister implementations need more than five
times 623 (the dimensional equidistribution property) memory accesses.  In
short it is roughly more than 3000 times(!!!) slower than the current
implementation! :-(

So in the time to compute one Mersenne Twister algorithm random number, for
most scenes* a whole ray can be traced...

    Thorsten


* "most" because intersections with a certain object types can take almost
infinitely long - an isosurface.  And note that really only one intersection
needs to be computed per ray when proper bounding is used and all objects
are bound.
____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

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