Summary

REBOUND is a highly flexible and efficient open-source N-body integrator designed for astrophysical simulations. It enables researchers and engineers to accurately model the gravitational dynamics of systems like stars, planets, and moons, offering significant computational advantages and ease of use through its Python interface and browser-based examples.

How It Works

The core of REBOUND is written in C99, providing a thread-safe shared library. It features a diverse suite of numerical integrators, including symplectic (WHFast, SEI, LEAPFROG, EOS), hybrid symplectic (MERCURIUS, TRACE), and high-order adaptive time-stepping methods (IAS15). This variety allows for accurate and efficient solutions across different dynamical regimes, from long-term planetary system evolution to close encounters and arbitrary coupled ODEs for phenomena like tides and spin.

Quick Start & Requirements

• Installation: Python module: pip install rebound. C version: git clone https://github.com/hannorein/rebound && cd rebound/examples/shearing_sheet && make.
• Prerequisites: No external library dependencies for the core C code.
• Resources: Browser-runnable C examples are available.
• Links: Documentation & Examples: https://rebound.hanno-rein.de, YouTube: https://www.youtube.com/channel/UCNmrCzxcmWVTBwtDPPLxkkw.

Highlighted Details

• Offers specialized integrators like WHFast (SIMD AVX512 parallelized), MERCURIUS (hybrid for close encounters), and IAS15 (high-accuracy adaptive).
• Supports collisional/granular dynamics and integration of user-defined ODEs for tides, spin, etc.
• Includes real-time, 3D visualization for both C and Python interfaces.
• Browser-based C examples allow immediate testing without local installation.

Maintenance & Community

The project is primarily maintained by Hanno Rein. Community support is available via GitHub issues. A strict policy prohibits AI/LLM-generated contributions to ensure human effort in code review.

Licensing & Compatibility

REBOUND is distributed under the GNU General Public License v3 or later (GPL-3.0-or-later). This copyleft license requires any derivative works to also be released under the GPL, potentially restricting integration into closed-source commercial products.

Limitations & Caveats

MPI parallelization is limited to specific use cases. The strict AI/LLM contribution policy may deter automated submissions. The GPL license imposes copyleft requirements on modifications and derivative works.