Code development

Scientific software development is a crucial aspect of computational (astro-)physics. With the progess made over the past decades, numerical methods as well as implementations have evolved and increased in complexity. The scope of simulation codes has increased accordingly, such that the question on how to organize development becomes important for further scientific progress.

This version of Arepo is intended as a basis, providing an efficient code structure and state of the art numerical techniques for gravity and hydrodynamics. The code is completely documented and should allow computational astrophysicists to develop their own specialized modules on top of it. Practically, this is best done by hosting an own repository for the development, which is occasonally updated from the main repository to include latest bugfixes. For this workflow to work properly, it is helpful to keep the code-base relatively static. For this reason

the base version of the code is not meant to be extended in functionality.

This means that only bugfixes as well as updates in the documentation and examples will be included in revisions of this public release.

Issue reporting

A code of the scope of Arepo will inevitably have a number of issues and so far undiscovered bugs. Detection of all issues is very complicated and time-consuming work. This means in practice that we rely on users to actually report all bugs and issues they come across, helping us to improve the quality of the code. We therefore encourage users to report all issues they have, including things that remain unclear after reading the documentation. This way we hope to constantly improve the qualtiy of the code in all its aspects.

To organize this, we set up a code support forum ( which is publicly visible. To create posts on this forum, a registration with admin-approval is required. We encourage users to sign up under and make use of the forum whenever they have problems.

Issues reported in the forum will then be confirmed by one of the authors and added to the repository issue tracker, which serves as a to-do list for bug fixes and improvements to the code. Therefore, if a problem occurs, the first thing to check is whether there already exists an open issue, i.e. whether this is a known and confirmed problem.

Please whenever possible use the support forum instead of contacting the authors by email.

We encourage experienced users to provide help and answer some of the open questions on this forum.

Code extensions

Extensions should be hosted in separate repositories or branches of the main repository. We highly welcome such extensions and encourage developers to make them publicly available (under GNU GPL v3). While this can be done independently of the authors, we would encourage developers to inform the authors once there is a publicly available module they are willing to share, in order to have a list of available extensions on the code homepage.

Some guidelines for code extensions and new modules:

  • Strive for modularity

  • Minimize the number of changes in existing source code files to a few function calls and structured variables within existing elements.

  • The source code of a new modue should largely be in separate (i.e. new) files.

  • Document the module

  • All parameter and config-options should be clearly explained in this documentation. Feel free to add an addional page to this documentation explaining how your module works.

  • Document what each function does in the source code.

  • The file should have a short explanation for each added flag.

  • Verification and examples

  • If possible, create one or more addional examples illustrating and testing the module.