ScalapackFx - Modern Fortran Interface for ScaLAPACK

The open source library ScalapackFx <https://github.com/dftbplus/scalapackfx>_ provides convenient modern Fortran (Fortran 2003) wrappers for the routines of the ScaLAPACK library. Currently mostly the routines related to diagonalization are covered.

The documentation is included inside the repository, but is also available at dftbplus.github.io <https://dftbplus.github.io/>_.

Installation

Prerequisites

• CMake (version >= 3.16)

• Fortran 2003 compatible Fortran compiler

• MPI-library and wrappers for your compiler

• ScaLAPACK and LAPACK libraries

• Fypp preprocessor <https://github.com/aradi/fypp>_

Building and installing the library

The library can be built and installed with the usual CMake-workflow::

FC=gfortran cmake -B _build -DCMAKE_INSTALL_PREFIX=$HOME/opt/scalapackfx cmake --build _build cmake --install _build

You can influence the configuration via CMake-variables. A list of those variables can be found in config.cmake <config.cmake>_. You can either modify the values directly there or pass them as command line option at the configuration phase, e.g.::

FC=ifort cmake -B _build
-DSCALAPACK_LIBRARY=mkl_scalapack_lp64;mkl_blacs_intelmpi_lp64
-DLAPACK_LIBRARY=mkl_intel_lp64;mkl_sequential;mkl_core

When customizing the external libraries as above, each of them will be searched for and checked for existence. You can disable these checks by setting the SCALAPACK_DETECTION and LAPACK_DETECTION variables to False (not recommended).

Testing

A few tests (and usage examples) can be found in the test/ subdirectory. The compiled test examples must be invoked from this directory, e.g.::

cd test mpirun -n 2 ../_build/test/test_det

Using the library

CMake build

• Make sure to add the root folder of the installed library to the CMAKE_PREFIX_PATH environment variable.

• Use find_package() in CMakeLists.txt to locate the library and link ScalapackFx::ScalapackFx to every target which relies directly on the library ::

  cmake_minimum_required(VERSION 3.16)

  project(TestScalapackFxBuild LANGUAGES Fortran)

  find_package(ScalapackFx REQUIRED)

  add_executable(test_build test_build.f90) target_link_libraries(test_build ScalapackFx::ScalapackFx)

Note: When ScalapackFx is found by CMake, it will try to resolve its own dependencies (ScaLAPACK and LAPACK) via the find_dependency() function. You can use your own finders for those dependencies as long as they export the targets Scalapack::Scalapack and LAPACK::LAPACK with the proper configuration as ScalapackFx uses those as link targets through the target_link_libraries() function. If those targets do not exists when ScalapackFx is being searched for, the custom finders shipped with ScalapackFx will be invoked to search for the necessary libraries.

Pkg-config build

• Make sure to add the lib/pkgconfig folder of the installed library to the PKG_CONFIG_PATH environment variable.

• Query the include and library options needed for the build with the usual pkg-config commands::

  mpifort $(pkg-config --cflags mpifx) test_mpifxbuild.f90 $(pkg-config --libs mpifx)

  Note, that neither -cflags or --libs return any options related to your MPI-framework nor is the MPI-framework specified as dependency in the pkg-config file. Use the MPI-wrapper of your compiler to compile and link your executable or pass the additional include and library options by hand.

License

ScalapackFx is licensed under the BSD-2-Clause License <LICENSE>_.