News | Downloading GNU MCSim | Documentation | Installation | Mailing lists | Contributed material and related links | Getting involved | Licensing


GNU MCSim is a simulation package, written in C, which allows you to:


Delay differential equations in GNU MCSim

GNU MCSim can now rather easily solve delay differential equations. This is not perfect as it requires the use of Inline statements in the model, but we are working on a cleaner implementation. You can still try it now. New code (in the sim/ directory) and a new example (examples/delay_diff_eqns/) are available on the MCSim project page on Savannah.

GNU MCSim and R (even under Microsoft Windows)

The basic tools needed to build and run GNU MCSim are not available to most users of Windows systems.
Fortunately, the R software (see, when properly installed with its Rtools (this requires administrator's rights), can compile and run GNU MCSim models. We have developed code and R scripts to compile GNU MCSim models to C code usable by the R package deSolve (to do that use the GNU MCSim "mod" model generator with the -R option) or by itself. This works under any operating system. You can then use deSolve to perform simulations of your models. The integators provided by deSolve are improved implementations of the lsode family of integrators (used also by GNU MCSim), and provide a few more options than GNU MCSim (in particular, "events", see the deSolve user manuals). However, if you need raw speed (say, for Markov chain Monte Carlo simulations) GNU MCSim is the fastest option.

Follow this link to download the corresponding scripts and code.

You need to have R and its Rtools (and optionally the deSolve package) installed.

Downloading GNU MCSim

The latest version of GNU MCSim (5.5.0) can be found on the main GNU ftp server: (via HTTP) and (via FTP). It can also be found on the GNU mirrors; please use a mirror if possible.

The gzipped tar archive contains:

Older versions can also be obtained on the GNU ftp mirrors and main page.

GNU MCSim development is hosted on See the MCSim project page on Savannah, where the latest development sources are publicly available.


The User's manual for GNU MCSim is available online, as is documentation for most GNU software. You may also find more information about GNU MCSim by running info mcsim, or by looking at /usr/share/mcsim/doc, or similar directories on your system.

Check also the User's Manual update file provided with the source code for last minute updates and tips.


To install GNU MCSim, you will need a C compiler and linker to compile the sources and obtain executables. For any machine we recommend the GNU gcc compiler, but standard C compilers should also work.

Versions 5.0.0 up to 5.3.1 required GNU Scientific Library (gsl) to be installed. With version 5.4.0, GNU gsl becomes optional (but recommended).

Versions above 5.4.0 also prefers libSBML v4.2.0 or above to be installed, but that is not needed if you do not want to read SBML model files.

The user's manual (online here) provides detailed instructions for installation for several platforms.

Mailing lists

GNU MCSim has the following mailing lists:

Announcements about GNU MCSim and most other GNU software are made on info-gnu (archive). See also info-mcsim.

Security reports that should not be made immediately public can be sent directly to the maintainer. If there is no response to an urgent issue, you can escalate to the general security mailing list for advice.

You can also look at the same lists, GNU MCSim help, and GNU MCSim bug report, on the gmane portal which has spam control.

Contributed material and related links

Getting involved

Development of GNU MCSim, and GNU in general, is a volunteer effort, and you can contribute. For information, please read How to help GNU. If you'd like to get involved, it's a good idea to join the discussion mailing list (see above).

For development sources, issue trackers, and other information, please see the GNU MCSim project page at
GNU MCSim is currently being maintained by Frederic Y. Bois. Please use the mailing lists for contact.


GNU MCSim is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

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The Free Software Foundation is the principal organizational sponsor of the GNU Operating System. Support GNU and the FSF by buying manuals and gear, joining the FSF as an associate member, or making a donation, either directly to the FSF or via Flattr.

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