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Installation

Choosing between C and Python

You can use either C or Python when working with REBOUND. Which programming language you want to use depends on your preference and your specific application. In short:

  • If you want to set up a planetary system, visualize data with matplotlib, and integrate your simulation with one of the built-in integrators then use the Python version. It's quick and easy to use.
  • If you want to run large simulations with millions of particles, develop your own integrator, use the distributed tree code with MPI, OpenMP parallelization, or OpenGL visualization, then use the C version. C gives you the best performance and direct access to all the REBOUND internals.

Note

All the computationally expensive parts of REBOUND are written in C. So even if you use the Python version, your simulation will run very efficiently. If you want to extend REBOUND, for example to include an additional non-gravitational force, you can do that in both C or Python. However, for complicated force routines, a C implementation of your function would most likely be significantly faster.

Installation via pip

Python Wheels

Starting with REBOUND version 3.28, we provide Python Wheels for REBOUND. This makes installing REBOUND easier on a wide variety of systems. For optimal performance, you can compile REBOUND yourself with optimizations flags that specifically target your system.

If you just want to try out REBOUND or don't plan to modify it in any way, then the easiest way to install the python version of REBOUND is pip (the Package Installer for Python). Simply type the following command into a terminal:

pip install rebound

If you have trouble installing a package with pip, consider using a virtual environment. Also, make sure your version of pip is not too old. You can update pip with pip itself: 

pip install --upgrade pip

Installation via git

We use the git as a version control system for REBOUND. If you want to use the C version of REBOUND or plan to make any modifications to REBOUND, you can clone the repository to your computer. Make sure you have git installed, then type the following command in a terminal:

git clone https://github.com/hannorein/rebound

This will create a new directory names rebound/ which contains all the source code, examples, and documentation. To use the python version of REBOUND, go to the rebound/ directory, then install REBOUND with 

pip install -e .
You should now be able to import REBOUND from python.

Compiling the C version of REBOUND

Examples

If you look at any of the examples in the examples/ sub-directories, you'll see one problem.c file and one Makefile. All the REBOUND code itself is in the src/ directory. This setup keeps the different projects nicely separated from the shared REBOUND code. To compile one of the examples, go to the example's directory and type make. This triggers the following tasks:

  1. The Makefile in the example directory sets up various environment variables. These determine settings like compiler optimization flags and which libraries are included (see below).
  2. Next, the Makefile in the src/ directory gets called. This compiles the entire REBOUND code into a shared library.
  3. It then creates a symbolic link from the current directory to the location of the shared library in the src/ directory. (On Windows the Makefile simply copies the shared library instead of making a symbolic link)
  4. Finally, it compiles your own code, the problem.c file and links it to the REBOUND shared library.

You can execute your program with ./rebound (or rebound.exe on Windows). After you edit either the problem.c file or any file in the src/ directory, you can simply type make again to recompile your program. If you change any of the environment variables, clean the build directory first, by executing make clean.

Your own project

The easiest way to start working on your own problem is to simply copy an example directory that is somewhat similar to what you want to do. This way, all your project's source and data files will be in one directory, separate from the main REBOUND source files in src/.

Alternatively, you can also install the shared REBOUND library in a global directory (e.g. /usr/lib/) and the header file in /usr/include/. Doing so will allow you (and any other users on your system) to use REBOUND from any directory. However, doing so requires root access and some knowledge on how Unix systems work. By simply replicating and modifying one of the examples, you'll avoid these complications.

Possible issues during compilation

The way we've designed REBOUND should make the compilation process extremely easy. You do not need to install any additional libraries (although you might want to, see below), and you do not need root access. You might nevertheless run into problems. Some of the most common issues are:

  • Missing compilers. Make sure you have a C compiler installed. If you are using a Mac, install the Xcode package which you can download for free on the App Store. Make sure the command line tools are installed. if you are on Windows, make sure you install the compilers that come with Visual studio (cl.exe) and have them available in your current command prompt (use the Developer Command Prompt for VS).
  • Missing glfw3 library. You can compile REBOUND with support for real-time OpenGL visualizations. This is an optional feature that requires the glfw3 library. If you are on a Mac, then the easiest way to install the glfw3 library is with homebrew: brew tap homebrew/versions && brew install glfw3. If you are on Linux, you can install it with your package manager, for example with sudo apt-get install libglfw3-dev. Alternatively, you can disable the OpenGL visualization in the Makefile by setting OPENGL=0. Then, execute make clean and try compiling the program again. Note that on some systems the glfw library is called glfw3 instead. In that case, change -lglfw to -lglfw3 in the file src/Makefile.defs.
  • Compiler optimizations. By default, REBOUND does not use the compiler flag -march=native which tries to optimize the code for the native architecture. If you want to have the most optimized code, add the -march=native or -mtune=native flag in the file src/Makefile.defs. If you use the python version, you can add compiler flags to setup.py. This might improve performance significantly.
  • Floating point contractions. Some compilers (e.g. clang) optimize code by contracting certain floating point operations (e.g. a multiplication and an addition become one fused multiply-add instruction). This improves performance but might prevent you from reproducing results exactly. You can turn off fused multiply-add instruction with the -ffp-contract=off compiler flag. If you use the python version, you can set the FFP_CONTRACT_OFF environment variable before installing REBOUND.

Running REBOUND on Windows

There are several ways to run REBOUND on Windows.

Python

You can install the python version of REBOUND using pip: 

pip install -e .
This will download the latest python wheel and install it on your system.

Windows Subsystem for Linux (WSL)

You can run the C-version of REBOUND using the Windows Subsystem for Linux (WSL). You will need make and a compiler, such as gcc. These can be installed within WSL with the following command: 

sudo apt-install make gcc
Then, you can follow the above instructions for Linux. Start by download REBOUND, for example using git: 
git clone https://github.com/hannorein/rebound
Then, compile and run a simple C-example with the following commands: 
cd rebound/examples/simplest
make
./rebound

Native Windows Builds

Note

The native Windows support for REBOUND is relatively new. Several features are currently not supported on native Windows builds: OpenMP, MPI, OpenGL, and AVX512. Please file a bug report on github if you require any of these featured or if you encounter any other problems.

Since version 3.28, you can also run REBOUND natively on Windows. You need to install make and enable the Microsoft Visual Studio compiler. Once you have downloaded the source code of REBOUND, open the Developer Command Prompt for VS or the Windows PowerShell on your system and go to the REBOUND source code. Then, compile and run a simple C-example with the following commands: 

cd examples
cd simplest
make
rebound.exe