[ns] randomness in simulation

[umair shah]

Hey could anyone tell me how to introduce randomness in my simulation ,seed 
value changing ,
if i use seed different for every run ,i get the different results right ? then 
i take average  for close approximation ,but what about plotting graph ? and is 
seed changed with ./sedest utility or from another command ? i read on mailing 
list 
set nextseed 0.0
  proc randomNumber { min max } {
       global nextseed
       global defaultRNG
       $defaultRNG seed $nextseed
       set nRNG [new RNG]
       $nRNG next-substream
       set num_ [new RandomVariable/Uniform]
       $num_ set min_ $min
       $num_ set max_ $max
       $num_ use-rng $nRNG
       set nextseed [expr round([$num_ value])]
but i don't understand that ?quick reply is needed,
       return $nextseed