Dear Jesús,
The NEST Simulator documentation on parallel computing has a section
regarding reproducibility:
https://nest-simulator.readthedocs.io/en/stable/hpc/parallel_computing.html
"To achieve the same simulation results even when using different
parallelization strategies, the number of virtual processes has to be
kept constant. A simulation with a specific number of virtual processes
will always yield the same results, no matter how they are distributed
over threads and processes, given that the seeds for the random number
generators of the different virtual processes are the same (see Random
numbers in NEST)."
Each virtual process has its own instance (and unique seed) in the
random number generator. This will result in different typologies and
random current/spikes generated. What you are describing is expected
behavior.
Sincerely,
Wouter
On 26-Jul-23 12:10, Jesus Espinoza wrote:
Hello everyone,
I am writing to the NEST mailing list as I have encountered an issue in
my simulation script, and I would greatly appreciate your insights.
The problem I am facing is that the membrane potential time course for a
simulation with a fixed indegree seems to be dependent on the number of
virtual processes (`total_num_virtual_procs`). Interestingly, this
behavior does not occur for simulations with all-to-all connectivity.
The simulation involves a network with the following architecture: 5
`spike_generator` nodes connected to 5 `parrot_neuron` nodes with
(all-to-all), which are further connected to 5 `iaf_psc_delta` neurons
(all-to-all). The connections between the `iaf_psc_delta` neurons have
an `fixed_indegree` of 2. A voltmeter is used to monitor the membrane
potentials of these 5 neurons, and the simulation runs for 100 ms.
The issue arises when I vary the number of virtual processes
(`total_num_virtual_procs`). I have tested the values 1, 2, and 4, and I
have noticed that the plot of the membrane potentials at the end of the
simulation differs for each `total_num_virtual_procs` value.
Additionally, when I print the table of connections, I observe that the
weights between the `iaf_psc_delta` neurons are also influenced by the
number of virtual processes.
I have attached the simulation script and three images showing the plot
for each `total_num_virtual_procs` value. The experiments were conducted
on my personal Ubuntu machine.
The version of NEST that I am using is the latest at the time of writing
this message, with commit `b9514cce789fb0b2c0dfbd9d0894d3986f743021`,
authored by Abigail Morrison <morrison(a)fz-juelich.de> on Tue Jul 18
23:46:22 2023 +0200.
I would be grateful for any suggestions or explanations regarding this
issue, as it hinders the reproducibility of my results.
Thank you in advance for your valuable help and support.
Best regards,
Jesus Espinoza.
--
Jesús Espinoza
Bergische Universität Wuppertal
Fakultät für Mathematik und Naturwissenschaften Wissenschaftliches
Rechnen und Hochleistungsrechnen Gaußstraße 20
42119 Wuppertal
Germany
E-Mail: espinozavalverd{at}uni-wuppertal.de
_______________________________________________
NEST Users mailing list -- users(a)nest-simulator.org
To unsubscribe send an email to users-leave(a)nest-simulator.org
--
Wouter Klijn <w.klijn(a)fz-juelich.de>
Team Leader Multiscale Simulation and Design
Simulation and Datalab Neuroscience
Jülich Supercomputing Centre
Institute for Advanced Simulation
Forschungszentrum Jülich
http://www.fz-juelich.de/ias/jsc/slns
Office: +49 2461 61-3523
Fax # : +49 2461 61-6656
---------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------
Forschungszentrum Juelich GmbH
52425 Juelich
Sitz der Gesellschaft: Juelich
Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
Vorsitzender des Aufsichtsrats: MinDir Stefan Müller
Geschaeftsfuehrung: Prof. Dr.-Ing. Wolfgang Marquardt (Vorsitzender),
Karsten Beneke (stellv. Vorsitzender), Dr. Ir. Pieter Jansens,
Prof. Dr. Astrid Lambrecht, Prof. Dr. Frauke Melchior
---------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------