Development prerequisites

Tool	Requirement
Git	With submodule support; BART and FINUFFT are the submodules external/bart and external/finufft. FINUFFT’s build also fetches the xsimd, POET and DUCC0 versions it pins, and CCCL for a CUDA build; CPM_SOURCE_CACHE keeps them between builds
Python	3.10 or later, with PyTorch installed first as described in Installation
C and C++ compiler	clang, or GCC 14 or later. BART’s nested functions are compiled as Blocks by clang and as heap trampolines (-ftrampoline-impl=heap) by GCC 14; CMake rejects older GCC at configuration
CMake	3.25 or later, with Ninja or Make
OpenMP	Linux: the runtime matching the compiler, for example libomp-dev with clang on Debian and Ubuntu. macOS: brew install libomp, for omp.h only; the library links against PyTorch’s runtime. Without it the build fails unless -DBARTORCH_OPENMP=OFF asks for a single-threaded library
CUDA (optional)	A CUDA toolkit with nvcc for -DBARTORCH_CUDA=ON, 12.1 or later for compute capability 9.0; a CUDA build of PyTorch does not include a compiler

FINUFFT and cuFINUFFT are compiled into the library from external/finufft; no FINUFFT package is installed or used. The dev extra installs SimpleITK for the correction and motion tests; pip install mkl deepinv enables the tests that need MKL and the DeepInverse adapter, and pip install PyHySCO the susceptibility-correction tests.

On Windows the compiler is clang from MSYS2’s CLANG64 environment, with the packages mingw-w64-clang-x86_64-{clang,cmake,ninja,llvm-openmp,llvm-tools}, clang64/bin on PATH and CMAKE_GENERATOR=Ninja. The build links against the OpenMP runtime PyTorch installs rather than MSYS2’s, and loads into the official CPython with nothing from MSYS2 at run time. There is no CUDA build on Windows.