Installation and Build Process

Installation of FTorch is done by CMake.

This is controlled by the CMakeLists.txt file in src/.

Basic instructions

To build the library, first clone it from GitHub to your local machine and then run:

cd FTorch/src/
mkdir build
cd build

Then invoke CMake with the Release build option, plus any other options as required from the table below in CMake build options (note: you will likely need to add some of these options to enforce a consistent build on your machine):

cmake .. -DCMAKE_BUILD_TYPE=Release

Finally build and install the library using:

cmake --build . --target install

or, if you want to separate these steps:

cmake --build .
cmake --install .

Note: if you are building on Windows please refer to the Windows install guidance as the process will likely differ from the UNIX-based stsyems covered here.

CMake build options

FTorch Library

It is likely that you will need to provide at least the CMAKE_PREFIX_PATH flag.
The following CMake flags are available and can be passed as arguments through -D<Option>=<Value>:

Option Value Description
CMAKE_Fortran_COMPILER ifort / gfortran Specify a Fortran compiler to build the library with. This should match the Fortran compiler you're using to build the code you are calling this library from.1
CMAKE_C_COMPILER icc / gcc Specify a C compiler to build the library with.1
CMAKE_CXX_COMPILER icpc / g++ Specify a C++ compiler to build the library with.1
CMAKE_PREFIX_PATH </path/to/libTorch/> Location of Torch installation2
CMAKE_INSTALL_PREFIX </path/to/install/lib/at/> Location at which the library files should be installed. By default this is /usr/local
CMAKE_BUILD_TYPE Release / Debug Specifies build type. The default is Debug, use Release for production code
CMAKE_BUILD_TESTS TRUE / FALSE Specifies whether to compile FTorch's test suite as part of the build.
ENABLE_CUDA TRUE / FALSE Specifies whether to check for and enable CUDA3

1 On Windows this may need to be the full path to the compiler if CMake cannot locate it by default. 2 The path to the Torch installation needs to allow CMake to locate the relevant Torch CMake files.
If Torch has been installed as libtorch then this should be the absolute path to the unzipped libtorch distribution. If Torch has been installed as PyTorch in a Python venv (virtual environment), e.g. with pip install torch, then this should be </path/to/venv/>lib/python<3.xx>/site-packages/torch/.

3 This is often overridden by PyTorch. When installing with pip, the index-url flag can be used to ensure a CPU or GPU only version is installed, e.g. pip install torch --index-url https://download.pytorch.org/whl/cpu or pip install torch --index-url https://download.pytorch.org/whl/cu118 (for CUDA 11.8). URLs for alternative versions can be found here.

For example, to build on a unix system using the gnu compilers and install to $HOME/FTorchbin/ we would need to run:

cmake .. \
-DCMAKE_BUILD_TYPE=Release \
-DCMAKE_Fortran_COMPILER=gfortran \
-DCMAKE_C_COMPILER=gcc \
-DCMAKE_CXX_COMPILER=g++ \
-DCMAKE_PREFIX_PATH=/path/to/venv/lib/python3.xx/site-packages/torch/ \
-DCMAKE_INSTALL_PREFIX=~/FTorchbin

Once this completes you should be able to generate the code and install using:

cmake --build . --target install

Note: If you are using CMake < 3.15 then you will need to build and install separately using the make system specific commands. For example, if using make on UNIX this would be:

make
make install

Installation will place the following directories at the install location:

  • CMAKE_INSTALL_PREFIX/include/ - contains C header and Fortran mod files
  • CMAKE_INSTALL_PREFIX/lib64/ - contains cmake directory and .so files

Note: In a Windows environment this will require administrator privileges for the default install location.

Other projects using CMake

We generally advise building projects that make use of FTorch with CMake where possible.

If doing this you need to include the following in the CMakeLists.txt file to find the FTorch installation and link it to the executable.

find_package(FTorch)
target_link_libraries( <executable> PRIVATE FTorch::ftorch )
message(STATUS "Building with Fortran PyTorch coupling")

You will then need to use the -DFTorch_DIR=</path/to/install/location> flag when running CMake.

Building other projects with make

To build a project with make you need to include the FTorch library when compiling and link the executable against it.

To compile with make add the following compiler flag when compiling files that use ftorch:

FCFLAGS += -I<path/to/install/location>/include/ftorch

When compiling the final executable add the following link flag:

LDFLAGS += -L<path/to/install/location>/lib64 -lftorch

You may also need to add the location of the .so files to your LD_LIBRARY_PATH unless installing in a default location:

export LD_LIBRARY_PATH = $LD_LIBRARY_PATH:<path/to/installation>/lib64