1.2. What does a LAMMPS version mean¶
The LAMMPS “version” is the date when it was released, such as 1 May 2014. LAMMPS is updated continuously, and we aim to keep it working correctly and reliably at all times. You can follow its development in a public git repository on GitHub.
Modifications of the LAMMPS source code (like bug fixes, code refactors, updates to existing features, or addition of new features) are organized into pull requests. Pull requests will be merged into the develop branch of the git repository after they pass automated testing and code review by the LAMMPS developers. When a sufficient number of changes have accumulated and the develop branch version passes an extended set of automated tests, we release it as a feature release (or patch release), which are currently made every 4 to 8 weeks. The release branch of the git repository is updated with every such release. A summary of the most important changes of the patch releases are on this website page. More detailed release notes are available on GitHub.
Once or twice a year, we have a “stabilization period” where we apply only bug fixes and small, non-intrusive changes to the develop branch. At the same time, the code is subjected to more detailed and thorough manual testing than the default automated testing. Also, several variants of static code analysis are run to improve the overall code quality, consistency, and compliance with programming standards, best practices and style conventions.
The latest patch release after such a period is then also labeled as a stable version and the stable branch is updated with it. Between stable releases, we occasionally release updates to the stable release containing only bug fixes and updates back-ported from the develop branch and update the stable branch accordingly.
Each version of LAMMPS contains all the documented features up to and including its version date. For recently added features, we add markers to the documentation at which specific LAMMPS version a feature or keyword was added or significantly changed.
The version date is printed to the screen and log file every time you run LAMMPS. It is also in the file src/version.h and in the LAMMPS directory name created when you unpack a tarball. And it is on the first page of the manual.
If you browse the HTML pages of the online version of the LAMMPS manual, they will by default describe the most current patch release version of LAMMPS. In the navigation bar on the bottom left, there is the option to view instead the documentation for the most recent stable version or the documentation corresponding to the state of the development branch.
If you browse the HTML pages included in your downloaded tarball, they describe the version you have, which may be older than the online version.