This code and accompanying documentation was the culmination of a couple years of independent research on N-Body simulations in galactic astrophyics that I undertook as part of my education at Reed College from 2011 to 2013. It was designed to be useful to students at Reed who want either a pre-built code to use to study some problem, or a comprehensive guide to building one's own N-Body simulation code (which can be surprisingly hard to find). In this light, I made an effort to document everything extremely well and to include detailed conceptual guides (see the attached PDFs.)

The code itself, which uses an adaptive-timestep algorithm and a Barnes-Hut Treecode force calculation routine, is designed to be used as easily as possible, with the user only needing to modify a few input parameters. For a PDF guide to Barnes-Hut Treecodes in general and how to edit this code, see the treecode guide.

Additionally included is code used to construct the initial conditions of a disk galaxy using the Hernquist Method. The methods used there are described here.

To use you will need the GNU compiler. On Macs, this comes bundled with XCode developer tools.

To run the main integrator, first edit the config options in main.cpp then compile and run with

make -f nbd.make
./nbody

The initial conditions routine is found in makegalaxy.cpp. To use, compile and run with

make -f init.make
./init

Enjoy!