xpermLibraryLink

This is a fork of xperm C-sources used in the xAct project. The purpose of this fork is to replace the WSTP connection used by the original xperm C-source by a newer and faster LibraryLink connection. This is a shared library that is loaded on-demand when required.

Prerequisites

• A working installation of xAct.
• cmake >= 3.0 (only for building from source).
• A C\C++ compiler (only for building from source).

Precompiled libraries

If you just want a ready to use compiled library you can simply download it from the binaries folder of this repository (choose the library suitable for your platform). You should then copy the library to one of the directories that is in the $LibraryPath variable (this is a Mathematica variable that you can check from within a Mathematica session).

General build and installation instructions

Linux and MacOS

This follows the standard cmake procedure and as a result a shared library is built. We explain the build procedure for Unix operating systems (it should work for other operating systems by doing suitable changes).

• Change to the folder xpermLibraryLink and inside it create a build directory:

$cd xpermLibraryLink
$mkdir build

• Change to the build directory and use cmake

$cd build
$cmake -DCMAKE_INSTALL_PREFIX=your_install_dir ..

your_install_dir must be one of the directories contained in the variable $LibraryPath (this is a Mathematica variable that you can check from within your xAct session).

• If you have several Mathematica installations you can select one of them by using the following cmakeswitch:

$cmake -DWolframLanguage_INSTALL_DIR=/usr/local/Wolfram/Mathematica/13.1 -DCMAKE_INSTALL_PREFIX=your_install_dir ..

Here we selected the Mathematica 13.1 installation directory. If you wish to select another one please change accordingly.

• If cmake reports no errors then you can build and install without changing directory:

$make
$make install

• If the previous step succeeds then you can test your installation using the notebook xpermLibraryLinkSample.nb that you can find in the root folder of this project.

Windows

We explain the compilation procedure using the development tools included in Visual Studio community edition. When installing Visual Studio you need to choose in step 4 the "Desktop & Mobile workloads" (that brings the C\C++ compilers) and in step 5 (Individual Components) you need to tick manually CMake. Since we are going to build the xperm library using the system terminal we need to tell the shell interpreter where the cmake executable is. To that end please go to Windows "Advanced system settings" and click on the button "Environment Variables". There, you need to look for the Path variable and add the route where the cmake executable was installed. This should be

C:\Program Files\microsoft Visual Studio\Community\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin

After this you can start the build procedure:

• Open a terminal (Windows PowerShell) change to the project directory xpermLibraryLink, create the build directory and change to it

PS C:\Users\username\xpermLibraryLink> mkdir build

PS C:\Users\username\xpermLibraryLink> cd build

Next use cmake in the following way

PS C:\Users\username\xpermLibraryLink\build> cmake -DCMAKE_INSTALL_PREFIX=C:\Users\username\AppData\Roaming\Mathematica\SystemFiles\LibraryResources\Windows-x86-64 ..

Here, we told cmake to install the library in one of the directories stored in the variable $LibraryPath using the CMAKE_INSTALL_PREFIX switch. After this we can compile and install the library:

PS C:\Users\username\xpermLibraryLink\build> cmake --build .

PS C:\Users\username\xpermLibraryLink\build> cmake --build . --target install