Overview

The linalg library package is a set of selected functions and subroutines from BLAS and LAPACK as they are used by and bundled with the LAMMPS MD code. While the original BLAS/LAPACK reference implementation from the Netlib servers are written in a portable Fortran dialect, this library uses the f2c tool tools to convert them to C++ while maintaining the expected binary interface from the most common Fortran compilers on Linux, macOS, Windows platforms. This allows to use it as a drop-in replacement in case there is no compatible BLAS/LAPACK binary library package or no Fortran compiler anavailable. It can be compiled with the same C++ compiler (minimum C++-11 standard) as the LAMMPS code itself.

The purpose of this package is to provide the source for the translated C++ files bundled with LAMMPS and easily allow to create updated versions for new LAPACK releases or add new functionality if required by added LAMMPS functionality through updating or adding to the Fortran sources and re-running the translation to C++.

Most of the original Fortran code can be translated without change. Those are placed into the fortran folder. A few other Fortran files need some small modifications to make them compatible with the f2c translator. In addition a few BLAS/LAPACK support functions (e.g. DLAMCH or XERBLA) have been directly implemented in C++. Finally, a few functions from the f2c runtime library are required as well. Those have been adapted to C++ and for typical platforms this library is supposed to be used on.

Version

The included Fortran files correspond to LAPACK version 3.12.0 released on November 24th, 2023.

License

Since the bulk of the code is an automated translation of the BLAS/LAPACK sources, the same licensing terms apply. Additional or replacement code is copyright (c) 2022, 2023 by Axel Kohlmeyer <[email protected]>.

Installation

This package uses CMake to set up the translation, and compilation plus a few tests. CMake version 3.16 or later is required. Also required are f2c, the GNU C++ compiler, clang-format, and sed. This has only been tested on a Linux machine.

Running the command:

cmake -S . -B build

Will set up a build folder and

cmake --build build

will do the translation and also try to compile the generated C++ files into a library as well as create a compressed tar file with the translated sources in the build folder.

If a suitable Fortran compiler was found, also a couple of tests for BLAS functions are configured and can be run with ctest.

ctest --test-dir build