[Ns-developers] ns3: random numbers

[George Riley]

>> As an end-user, I do not really understand the concept of  
>> substream but
>> I certainly would favor using a constant seed by default to ensure  
>> that
>> two runs of the same code generate the same results, by default.
>>
>> Mathieu
>
> Actually, having a constant seed by default would be my preference  
> also.  This is currently how ns-2 works -- unless you use ns-random  
> 0 (or something like that).  Since my email address was at some  
> point in the code for the RNG, I've received several emails from  
> users asking why their simulations give the same results every  
> time.  So, agreeing to a random seed by default was my concession  
> to such users.
Clearly, whether to by default use a random or constant seed is a  
matter of opinion.
I'm in the camp that says if my simulation has random variables, it  
should behave differently every run.
If I want  reproducible results, I will set the global seed; but the  
default should be that random
variables are indeed random (IMHO).

George
>
> -Michele
>