Exactly what it says on the tin.

accretion is the actual integrator. Build with make all and feed an initial state into its stdin. A succession of states will exit stdout. stderr carries debug messages; by default, the number of bodies and current step number. Use -v 0 to turn this off, or -v 2 to see full state dumps in human readable form at every step (default is -v 1). An example run might look like:

make all
./gaussian_cloud -n 2000 | ./accretion > out.bin

The folder init contains initial state generators. States are currently represented in a simple binary format to preserve precision:

[number of bodies: int, 4 bytes]
[body: 56 bytes, comprised of:
  [mass: double, 8 bytes]
  [position: 3 doubles, 24 bytes]
  [velocity: 3 doubles, 24 bytes]
]
[body]
[body]
...

Simulation output is a series of states marked by simulation times, i.e.:

[time 1: double, 8 bytes][state 1][time 2][state 2]...

Currently uses leapfrog method to integrate accelerations.

Sets of intersecting objects are considered to be undergoing a collision and get merged into a single object which has mass and momentum the sum of those of the colliders. Objects are taken to be spherical, with a constant density (specified in a header).

• gaussian cloud statistical property verification
• two-body integrator accuracy test
• better integration method
• tree-based gravity approximation
• a less stupid makefile
• a build folder to contain the mess
• visualization, someday in the future...?
• energy/momentum/other conservation checking
• state parser and conversion to human-readable form
• malformed input handling
• collision testing