Last revised on January 1, 2019


GRACOS is a software package (code) including a fast executable for cosmological N-body simulations and data analysis. GRACOS was developed at MIT and later at CITA by Alexander Shirokov, under the advice of Prof. Edmund Bertschinger.

The latest bugfix version gracos-9211-AA is now available (download it, or see the release notes for news).


GRACOS has been used to:

  • Generate first three dimensional computer simulation of cosmological caustics: Thesis.

  • Establish the effects of primordial non-gaussianities on large scale cosmological structure formation: 2008PhysRevD.7713514D

  • Explore the halo assembly bias in hierarchical superclaster structure formation: 2008ApJ...687...12D


  • Standard GNU build and install procedure
  • Embedded script environment
  • Cosmological initial conditions generator, including non-gaussian initial conditions
  • Particle data imager and mass density power spectrum estimator
  • Particle position and velocity integrator with a choice between KDK and DKD integration schemes; Plummer force softening
  • File input and output in multiple serial and one distributed data formats
  • Parallelization with Message Passing Interface (MPI) environment
  • Version specific documentaition in HTML and PDF formats included in each distribution
  • Free software, released under the GNU General Public License (GPL).


    The manual for GRACOS is available online and in PDF format. Technical description of the main optimization techniques specially developed for GRACOS: parallel domain decomposition with Hilbert curve, sorting, and the adaptive P3M are presented in Chapters 2 and 3 of Alexander Shirokov PhD Thesis at MIT (submitted in March 2005). Chapter 2 is also available as astro-ph/0505087. If you wish to cite GRACOS in your work we recommend the above two publications BibTeX.


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