Yop,
Thanks Maelstorm and acreil !
My concern was about cpu efficiency, and this slow random offset is clearly (dunno how to say it in english) the cherry on top of my pie !
Anyway for cpu I will use table lookup. The article talks about 'nonuniform logarithmic sampling with a floor of about zero', but I'll start with a 'normal' tablelookup.
Thanks,
Nau