FAQs

Installation

How can I install NEMO on 32-bit Windows?

NEMO's automated installer program is only compatible with 64-bit Windows. If you want to run NEMO on 32-bit Windows, please follow the instructions for GitHub installation of NEMO. As they explain, you'll need to download and install Julia, then add the NEMO package within Julia.

With GitHub installation, NEMO will be slower to start than if installed with the installer program. This is because the installer program supplies a pre-compiled session environment (system image) for Julia that includes support for NEMO. Without this component, Julia performs some of the compilation of NEMO each time NEMO is run. To create your own pre-compiled session environment for a 32-bit installation, you can use the PackageCompiler tool.

Can I install NEMO for all Windows users?

Yes, the easiest way to do this is to use the NEMO installer program. As of NEMO 1.7, the installer program installs NEMO for all Windows users. If you install NEMO from GitHub, you'll have to make sure Julia is installed for all users, and all users have access to a Julia environment that includes NEMO's Julia package. See the Julia documentation for details on Julia environments.

I got an error when I ran the NEMO installer program. What should I do?

If you're running the installer on Windows, make sure you're using a licensed copy of Windows 10 or 11 64-bit. The installer may not work on other versions of Windows, including Windows 7. If you've verified your operating system but are still encountering an error, click the "Show details" button in the installer and record the error message. You can then report the issue at the LEAP and NEMO support forum. When you do, please note which operating system and operating-system display language you're using.

Is there a silent mode for the NEMO installer program?

Yes, you can run the installer in silent mode with a /S switch.

Why won't my solver work with NEMO?

The first thing to do in case of problems with a solver is to check whether NEMO supports the solver. The NEMO team generally doesn't help to troubleshoot unsupported solvers. Note in particular that right now, NEMO is only compatible with versions 12.10 and 20.1 of CPLEX and versions 9.0 - 9.1 of Gurobi.

You should also make sure your solver is properly licensed. Proprietary solvers including CPLEX, Gurobi, Mosek, and Xpress require a license that must be obtained from their provider.

If you have a compatible, licensed solver but installed it after NEMO, the solver may not be connected to Julia. If you installed NEMO with the NEMO installer program, you can correct this problem by rerunning the installer. Otherwise, try building the Julia package for the solver (CPLEX, Gurobi, or Xpress), for example:

julia> using Pkg

julia> Pkg.build("CPLEX")

Performance

Why is my model slow?

See Performance tips for some ideas.

Training and user support

Are there training exercises for NEMO?

An introductory training lecture on NEMO and using NEMO with LEAP is available on the LEAP YouTube Channel. The NEMO team is working on NEMO exercises and will link them here when they're ready.

Where should I report problems with NEMO?

Please report issues at the LEAP and NEMO support forum. Before reporting an issue, check the forum to see if your question has already been asked and answered. If you do submit an issue report, be specific and include steps to reproduce the problem.

Using NEMO with LEAP

I'm getting a "database is locked error" when I try to calculate a NEMO scenario in LEAP. How can I resolve this?

There are several reasons why this error could occur.

• LEAP crashed while it was calculating a scenario with NEMO. In this case, you can fix the problem by stopping the crashed LEAP process (as well as any running Julia processes) in Window's Task Manager, or you can just reboot Windows.

• You opened a NEMO database for a scenario in LEAP's working directory (using a SQLite client such as DB Browser for SQLite), then tried to recalculate the scenario in LEAP. In this situation, LEAP attempts to overwrite the database but isn't able to. Once you close the database, LEAP should be able to proceed.

• LEAP isn't able to find the directory where it creates NEMO scenario databases. In principle, the LEAP installer should ensure this doesn't happen, but some users have reported this behavior. You can correct it by adding the path to the LEAP settings folder to the Windows environment variable named "PATH". You can find the path to the LEAP settings folder in LEAP at Settings -> Folders -> Settings.