NEST Users February 2026

users@nest-simulator.org

6 participants
5 discussions

Heaviside function in a Kernel?
by Jeanne Barthelemy 04 Mar '26

04 Mar '26

Dear all, This is a question about best practices for NESTML. I would like to build in the equations block a Kernel, such as for instance: "kernel inh_time_end = ((-0.00002*t*t)/(pow(tau,2.0)) + 0.0087*t/tau + 0.006)/tau" , but modulated by the heaviside function H depending on 200 - t (i.e., H(200.0 ms -t)). To sum up, I would like to get the following kernel: "kernel inh_time_end_modulated = H(200.0 ms -t)*((-0.00002*t*t)/(pow(tau,2.0)) + 0.0087*t/tau + 0.006)/tau" There does not appear to be a direct implementation of the heaviside function H in nestml. I tried to build my own function to convert booleans to 1.0 or 0.0 in my NestML model, upon the condition "200.0 ms > t", and use that instead of the heaviside, but the model is really slow to build on my laptop. I tried other versions with if conditions in the update block, or ternary operators, but they all led to bugs. So, I am unsure of the correct practice to implement an heaviside-modulated polynomial kernel. If anyone has a good and fast solution to propose I would be very happy to learn about it ! Thank you very much, Kind regards, Jeanne BARTHELEMY

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Open NEST Developer Video Conference Monday February 23, at 11:30 CET (UTC+0100)
by Dennis Terhorst 23 Feb '26

23 Feb '26

Dear NEST Users & Developers! I would like to invite you to our next fortnightly Open NEST Developer Video Conference today *Monday February 23, at 11:30 CET (UTC+0100).* As usual, in the Project team round, a contact person of each team will give a short statement summarizing ongoing and planned work in the team and highlight cross-cutting points that need discussion among the teams. The remainder of the meeting we would go into a more in-depth discussion of topics that came up on the mailing list or that are suggested by the teams. Feel free to join the meeting also if it’s just to bring your own quick questions for direct discussion in the in-depth section. Agenda * Welcome * Review of NEST User Mailing List * Project team round * In-depth discussion: /Support for three factor learning synapse NESTML/ The agenda for this meeting is also available online, see https://github.com/nest/nest-simulator/wiki/2026-02-23-Open-NEST-Developer-… <https://github.com/nest/nest-simulator/wiki/2026-02-23-Open-NEST-Developer-…> Looking forward to seeing you soon! Cheers, Dennis Terhorst Log-in information We use a virtual conference room provided by DFN <https://www.dfn.de/en/> (Deutsches Forschungsnetz). You can use the web client to connect. We however encourage everyone to use a headset for better audio quality or even a proper video conferencing system (see below) or software when available. Web client * Visit https://conf.dfn.de/webapp/conference/97938800 <https://conf.dfn.de/webapp/conference/97938800> * Enter your name and allow your browser to use camera and microphone * The conference does not need a PIN to join, just click join and you’re in. In case you see a dfnconf logo and the phrase “Auf den Meetingveranstalter warten”, just be patient, the meeting host needs to join first (a voice will tell you). VC system/software How to log in with a video conferencing system, depends on you VC system or software. * Using the H.323 protocol (eg Polycom): |vc.dfn.net##97938800| or |194.95.240.2##97938800| * Using the SIP protocol:97938800@vc.dfn.de <mailto:97938800@vc.dfn.de> * By telephone: |+49-30-200-97938800| For those who do not have a video conference system or suitable software, Polycom provides a pretty good free app for iOS and Android, so you can join from your tablet (Polycom RealPresence Mobile, available from AppStore/PlayStore). Note that firewalls may interfere with videoconferencing in various and sometimes confusing ways. For more technical information on logging in from various VC systems, please see http://vcc.zih.tu-dresden.de/index.php?linkid=1.1.3.4 <http://vcc.zih.tu-dresden.de/index.php?linkid=1.1.3.4> -- Dipl.-Phys. Dennis Terhorst Coordinator Software Development Institute for Advanced Simulation (IAS-6) Computational and Systems Neuroscience & JARA-Institute Brain Structure-Function Relationships (INM-10) Institute of Neuroscience and Medicine Jülich Research Center, Member of the Helmholz Association 52425 Jülich, Germany http://www.csn.fz-juelich.de/ --------------------------------------------------------------------------------------------- Forschungszentrum Jülich GmbH 52425 Jülich Sitz der Gesellschaft: Jülich Eingetragen im Handelsregister des Amtsgerichts Düren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDir Stefan Müller Geschäftsführung: Prof. Dr. Astrid Lambrecht (Vorsitzende), Dr. Stephanie Bauer (stellvertretende Vorsitzende), Prof. Dr. Ir. Pieter Jansens, Prof. Dr. Laurens Kuipers ---------------------------------------------------------------------------------------------

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NEST 3.9 incompatible with PyGSL and libpthread.so issue
by Pedro R. Pinheiro 20 Feb '26

20 Feb '26

Hi everyone. I have a couple of questions pertaining to NESTML and would appreciate some support. I use NEST via WSL with Ubuntu 24.04.3 LTS. More specifically, I use the micromamba extension on VS Code to manage virtual environments and install python packages via conda-forge. 1) When using NEST 3.9 I get an error saying that PyGSL is incompatible and the simulator returns me a warning saying the stiffness test will be skipped. [image: image.png] WARNING:root:PyGSL is not available. The stiffness test will be skipped. WARNING:root:Error when importing: No module named 'pygsl I didn't have this problem before, when I used NEST 3.8. My installation steps currently are essentially: micromamba install -c conda-forge nest-simulator=3.9 ipython cxx-compiler cmake make swig pkg-config pip install nestml When I try to install pygsl via micromamba the only version I can attempt is 2.6.2. Installing pygsl via pip also gives an error even if I have swig and pkg-config installed. 2) When generating a target using generate_target, I get the following error message: /.micromamba/envs/default/x86_64-conda-linux-gnu/sysroot/usr/lib/libpthread.so: No such file or directory I realised that while I do not have libpthread.so under that path I do have libpthread.so.0 and creating a symlink directing the former to the latter solves the problem. Is this acceptable? ln -s /.micromamba/envs/default/x86_64-conda-linux-gnu/sysroot/usr/lib/libpthread.so.0 /.micromamba/envs/default/x86_64-conda-linux-gnu/sysroot/usr/lib/libpthread.so 3) I would like to know if using NESTCodeGeneratorUtils.generate_code_for is better or equivalent to using generate_target. That's it for now. Thank you in advance for your help. Best, Pedro.

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NEST tutorial at the EBRAINS Student Conference: invitation
by Charl Linssen 09 Feb '26

09 Feb '26

Dear all, Please join us for a hands-on NEST tutorial at the EBRAINS Student Conference on Interdisciplinary Brain Research. The EBRAINS Student Conference offers an open platform for early career researchers to exchange innovative ideas across disciplines relevant to brain research and neuroscience. You will have the opportunity to learn about the various software tools on the EBRAINS platform, get first-hand experience using NEST Simulator and tools like NESTML and NEST Desktop, and ask questions and get expert feedback about using simulation in your own research. We will create models from the single synapse, to large-scale spiking neural networks. The conference takes place March 11-13th in Nice, France. Registration is open! Please visit the website for more information: https://ebrains.eu/news-and-events/events/2026/1st-ebrains-student-conferen… Looking forward to seeing you there! _____________________________________ Charl Linssen Ir. MSc Simulation and Data Lab Neuroscience Jülich Supercomputer Centre (JSC) Institute for Advanced Simulation Forschungszentrum Jülich GmbH c.linssen(a)fz-juelich.de +49 (0)2461 61-5269 _____________________________________

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Open NEST Developer Video Conference Monday February 9, at 11:30 CET (UTC+0100)
by Dennis Terhorst 09 Feb '26

09 Feb '26

Dear NEST Users & Developers! I would like to invite you to our next fortnightly Open NEST Developer Video Conference today *Monday February 9, at 11:30 CET (UTC+0100).* As usual, in the Project team round, a contact person of each team will give a short statement summarizing ongoing and planned work in the team and highlight cross-cutting points that need discussion among the teams. The remainder of the meeting we would go into a more in-depth discussion of topics that came up on the mailing list or that are suggested by the teams. Feel free to join the meeting also if it’s just to bring your own quick questions for direct discussion in the in-depth section. Agenda * Welcome * Review of NEST User Mailing List * Project team round * In-depth discussion The agenda for this meeting is also available online, see https://github.com/nest/nest-simulator/wiki/2026-02-09-Open-NEST-Developer-… <https://github.com/nest/nest-simulator/wiki/2026-02-09-Open-NEST-Developer-…> Looking forward to seeing you soon! Cheers, Dennis Terhorst Log-in information We use a virtual conference room provided by DFN <https://www.dfn.de/en/> (Deutsches Forschungsnetz). You can use the web client to connect. We however encourage everyone to use a headset for better audio quality or even a proper video conferencing system (see below) or software when available. Web client * Visit https://conf.dfn.de/webapp/conference/97938800 <https://conf.dfn.de/webapp/conference/97938800> * Enter your name and allow your browser to use camera and microphone * The conference does not need a PIN to join, just click join and you’re in. In case you see a dfnconf logo and the phrase “Auf den Meetingveranstalter warten”, just be patient, the meeting host needs to join first (a voice will tell you). VC system/software How to log in with a video conferencing system, depends on you VC system or software. * Using the H.323 protocol (eg Polycom): |vc.dfn.net##97938800| or |194.95.240.2##97938800| * Using the SIP protocol:97938800@vc.dfn.de <mailto:97938800@vc.dfn.de> * By telephone: |+49-30-200-97938800| For those who do not have a video conference system or suitable software, Polycom provides a pretty good free app for iOS and Android, so you can join from your tablet (Polycom RealPresence Mobile, available from AppStore/PlayStore). Note that firewalls may interfere with videoconferencing in various and sometimes confusing ways. For more technical information on logging in from various VC systems, please see http://vcc.zih.tu-dresden.de/index.php?linkid=1.1.3.4 <http://vcc.zih.tu-dresden.de/index.php?linkid=1.1.3.4> -- Dipl.-Phys. Dennis Terhorst Coordinator Software Development Institute for Advanced Simulation (IAS-6) Computational and Systems Neuroscience & JARA-Institute Brain Structure-Function Relationships (INM-10) Institute of Neuroscience and Medicine Jülich Research Center, Member of the Helmholz Association 52425 Jülich, Germany http://www.csn.fz-juelich.de/ --------------------------------------------------------------------------------------------- Forschungszentrum Jülich GmbH 52425 Jülich Sitz der Gesellschaft: Jülich Eingetragen im Handelsregister des Amtsgerichts Düren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDir Stefan Müller Geschäftsführung: Prof. Dr. Astrid Lambrecht (Vorsitzende), Dr. Stephanie Bauer (stellvertretende Vorsitzende), Prof. Dr. Ir. Pieter Jansens, Prof. Dr. Laurens Kuipers ---------------------------------------------------------------------------------------------

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