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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. Also, several variants of static code analysis are run regularly to maintain or improve the overall code quality, consistency, and compliance with programming standards, best practices and style conventions. You can follow its development in a public git repository on GitHub.

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.

1.2.1. Identifying the Version

The version date is printed to the screen and log file every time you run LAMMPS. There also is an indication, if a LAMMPS binary was compiled from version with modifications after a release. It is also visible in the file src/version.h and in the LAMMPS directory name created when you unpack a downloaded 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 feature 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.

1.2.2. LAMMPS releases, branches, and tags

_images/lammps-releases.png — Relations between releases, main branches, and tags in the LAMMPS git repository

Development

Modifications of the LAMMPS source code (like bug fixes, code refactoring, 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.

Feature Releases

When a sufficient number of new features and updates have accumulated and the LAMMPS version on the develop branch passes an extended set of automated tests, we release it as a feature release, which are currently made every 4 to 8 weeks. The release branch of the git repository is updated with every such feature release and a tag in the format patch_1May2014 is added. A summary of the most important changes of these releases for the current year are posted on this website page. More detailed release notes are available on GitHub.

Stable Releases

About once a year, we release a stable release version of LAMMPS. This is done after a “stabilization period” where we apply only bug fixes and small, non-intrusive changes to the develop branch but no new features. At the same time, the code is subjected to more detailed and thorough manual testing than the default automated testing. After such a stable release, both the release and the stable branches are updated and two tags are applied, a patch_1May2014 format and a stable_1May2014 format tag.

Stable Release Updates

Between stable releases, we collect bug fixes and updates back-ported from the develop branch in a branch called maintenance. From the maintenance branch we make occasional stable update releases and update the stable branch accordingly. The first update to the stable_1May2014 release would be tagged as stable_1May2014_update1. These updates contain no new features.