Here are some codes which I have used in my research. You are welcome to use the codes in your own work. If you do, please cite the relevant paper. If you make major improvements, please make your work publically available as well.

• Source code: bill.py
  Syntax-colored HTML version: bill.py.html
  (Created using python2html, available here)

  This code carries out computations related to the BKL billiard structures. It allows one to construct the Einstein-p-form systems corresponding to the A-E cosets in three dimensions, and to compactify them on manifolds with given Betti numbers. It uses the coweight construction to determine whether the compactified models are chaotic. The code can print out primitive Dynkin diagrams as well.

  It was developed as part of a project with, and benefited from helpful comments from, Marc Henneaux and Daniel Persson, both currently at ULB in Brussels.

  The code is written in Python, and uses the SciPy library to perform matrix computations. You'll need to have both installed on your system for this to work.

  Here's an example session, where we study the uncompactified B₄ model, and its b₂=b₃=0 compactification:
   
  user@host code/ $ python
  Python 2.4.4 (#1, Oct 18 2006, 10:34:39)
  [GCC 4.0.1 (Apple Computer, Inc. build 5341)] on darwin
  Type "help", "copyright", "credits" or "license" for more information.
  >>> import bill
  >>> b4=bill.cosetB(4)
  >>> print b4
  Original model cosetB
  Dominant walls ['EF2', 'BG3', 'S2', 'S3', 'S4', 'S5']
  Coweights (T,N,S) (5, 1, 0)
  Chaotic? True
  
  S2 o=>=o EF2
  |
  S3 o---o BG3
  |
  S4 o
  |
  S5 o
  >>> b4.setZeroBetti([2,3])
  >>> print b4
  Original model cosetB
  Dominant walls ['EF2', 'G', 'S2', 'S3', 'S4', 'S5']
  Coweights (T,N,S) (3, 2, 1)
  Chaotic? False
  
  S2 o=>=o EF2---o G
  |
  S3 o
  |
  S4 o---o G
  |
  S5 o
  
  EF2 o+<+o G
  >>>
   
  It can take a little practice to read the Dynkin diagrams. In the second diagram, one should read the walls to the right of each symmetry wall as those wall that are connected to it: the connection between EF2 and G is given in the last line, with the + symbols indicated the corresponding entry in the Cartan matrix is positive.

• magnetiCS.c

  This computes the primordial magnetic field spectrum from a cosmic string network. Also available from Mark Wyman's homepage. The relevant paper is JCAP02:001 (2008), and the project itself is described in a little more detail here.

  The code has a number of options, described in more detail in the source code file. These include switching the string network model (between the one-scale model and velocity-dependent one-scale model) as well as various options for tracking loop cohorts and data output.