Hello,

I have an issue regarding random generation in nest version 2.18 with Python3.6.
I attach a small python script that replicates my issue (less than 50 lines).

In short, I am trying to create two Poisson generators and connect them to the same neuron.

I noticed that if I reverse the order by which these Poisson generators are created (using the nest.Create()) function, then I get a different membrane potential response over time. 

In the code, noise_exc is created before noise_inh. If that order is reversed, the plot is different.

My hunch is that this has to do with how nest generates random numbers. 
So I tried to force the creation of Poisson generators by providing a seed (lines 15 and 18).
However this behavior persists. 

Do you have any insights as to why this happens?

At the end of the script (lines 32-43) I provide a trivial case of the desired behavior I am trying to replicate.

Thank you for your time

Angeliki 

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Angeliki Papadimitriou

Research Engineer

KTH Royal Institute of Technology

School of Electrical Engineering and Computer Science (EECS)
Division of Computational Science and Technology (CST)

Computational Brain Science Unit

Room 4438, Floor 4, Lindstedtsv
ägen 5
11428
 Stockholm, Sweden

angpap@kth.se