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A code for collisionless and gasdynamical cosmological simulations

Version : 1.1
Author(s) : Volker Springel ( , Naoki Yoshida (
License : GPL
Website :

Disk space required for installation is 23.32 Mb

After the package is installed it can be accessed using the command



The following printable documents will be installed :


In its current implementation, the serial and parallel versions of GADGET (GAlaxies with Dark matter and Gas intEracT1) support collisionless simulations and smoothed
particle hydrodynamics on serial or massively parallel computers. While the parallel code required substantial changes in certain parts of the computational algorithms, we have nevertheless
tried to keep the structure of the two codes, and their usuage, as similar as possible. In principle, it would be possible to merge the codes into one source, and employ large numbers of
compiler directives to generate serial or parallel behaviour as desired. However, we think that would make the code much more opaque, and would compromise one of our objectives, which is
to provide a clean, well-documented code that can be easily understood and modified by users. We therefore provide two separate versions of the code, one for serial and one for parallel

The code can be used for plain Newtonian dynamics, or for cosmological integrations in arbitrary cosmologies, both with or without periodic boundary conditions. The modeling of
hydrodynamics is optional. The code is fully adaptive both in space and in time.

The main reference for numerical and algorithmic aspects of the code is the paper `GADGET: A code for collisionless and gas-dynamical cosmological simulations', Springel, Yoshida White, 2000, submitted to New Astronomy (see preprint at astro-ph/0003162). In the following, this paper will be frequently referenced, and I recommend reading it before you attempt to use
the code.


Hierarchical multipole expansion (tree method) for gravitational forces (geometrical oct-tree, Barnes
Optional periodic boundary conditions (Ewald summation technique)

Smoothed particle hydrodynamics with fully adaptive smoothing lengths

Shear-reduced artificial viscosity

Individual timesteps of arbitrary size for all particles

Work-load balancing and dynamic tree updates

Efficient cell-opening criteria

Highly efficient integrator in the linear regime of gravitational clustering

Flexible control of all code options by a free-format parameterfile

Portable, well documented code, relying only on standard language/communication features

High raw computational speed and good scalability


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