# LAMMPS portability and compatibility

The primary form of distributing LAMMPS is through highly portable
source code. But also several ways of obtaining LAMMPS as [precompiled
packages or through automated build mechanisms](Install) exist. Most of
LAMMPS is written in C++, some support tools are written in Fortran or
Python or MATLAB.

## Programming language standards

Most of the C++ code currently requires a compiler compatible with the
C++11 standard, the KOKKOS package currently requires C++14. Most of the
Python code is written to be compatible with Python 3.5 or later or
Python 2.7. Some Python scripts *require* Python 3 and a few others
still need to be ported from Python 2 to Python 3.

## Build systems

LAMMPS can be compiled from source code using a (traditional) build
system based on shell scripts, a few shell utilities (grep, sed, cat,
tr) and the GNU make program. This requires running within a Bourne
shell (`/bin/sh`). Alternatively, a build system with different back
ends can be created using CMake. CMake must be at least version 3.10.

## Operating systems

The primary development platform for LAMMPS is Linux. Thus, the chances
for LAMMPS to compile without problems on Linux machines are the best.
Also, compilation and correct execution on macOS and Windows (using
Microsoft Visual C++) is checked automatically for largest part of the
source code. Some (optional) features are not compatible with all
operating systems, either through limitations of the corresponding
LAMMPS source code or through source code or build system
incompatibilities of required libraries.

Executables for Windows may be created natively using either Cygwin or
Visual Studio or with a Linux to Windows MinGW cross-compiler.

Additionally, FreeBSD and Solaris have been tested successfully.

## Compilers

The most commonly used compilers are the GNU compilers, but also Clang
and the Intel compilers have been successfully used on Linux, macOS, and
Windows. Also, the Nvidia HPC SDK (formerly PGI compilers) will compile
LAMMPS (tested on Linux).

## CPU architectures

The primary CPU architecture for running LAMMPS is 64-bit x86, but also
32-bit x86, and 64-bit ARM and PowerPC (64-bit, Little Endian) are
regularly tested.

## Portability compliance

Only a subset of the LAMMPS source code is fully compliant to all of the
above mentioned standards. This is rather typical for projects like
LAMMPS that largely depend on contributions from the user community. Not
all contributors are trained as programmers and not all of them have
access to multiple platforms for testing. As part of the continuous
integration process, however, all contributions are automatically tested
to compile, link, and pass some runtime tests on a selection of Linux
flavors, macOS, and Windows, and on Linux with different compilers. Thus
portability issues are often found before a pull request is merged.
Other platforms may be checked occasionally or when portability bugs are
reported.