# Installation

> NumKong for C++

With CMake `FetchContent`:

```cmake
include(FetchContent)

FetchContent_Declare(
    numkong
    GIT_REPOSITORY https://github.com/ashvardanian/NumKong.git
    GIT_SHALLOW TRUE
)
FetchContent_MakeAvailable(numkong)

target_link_libraries(my_target PRIVATE numkong::header) # or numkong::static, numkong::shared
```

Vendored:

```cmake
add_subdirectory(external/NumKong)
target_link_libraries(my_target PRIVATE numkong::header) # or numkong::static, numkong::shared
```

`numkong::static` and `numkong::shared` exist when `NUMKONG_BUILD_SHARED` is on, the default only for a top-level build.
An installed NumKong provides the same targets through `find_package(numkong CONFIG REQUIRED)`.

By default the headers declare every public function and the library defines it, each kernel once, in the unit of its capability.
`numkong::header` sets `NUMKONG_HEADER_ONLY=1` instead: every kernel compiles into your translation unit, and every dispatch point and finder returns `nk_missing_library_k`, so a header-only build calls a capability's kernel, like `nk_dot_f32_haswell`, directly.

### Building and Cross-Compiling

The build enforces C99 for the C layer and C++20 for the C++ layer.
[CONTRIBUTING.md](https://github.com/ashvardanian/NumKong/blob/main/CONTRIBUTING.md#building) lists the CMake presets and options, and [its cross-compilation section](https://github.com/ashvardanian/NumKong/blob/main/CONTRIBUTING.md#cross-compilation) the toolchain files in `cmake/` with a recipe for each target.
A translation unit linking `numkong::static` or `numkong::shared` sees declarations only, while `numkong::header` defines `NUMKONG_HEADER_ONLY=1` and compiles the kernels inline.
The library compiles every capability whose probe in `probes/` compiles, each scoped to its kernels by target pragmas, and dispatches between them by runtime detection.
LASX and POWER9 scope that way only under GCC 15 or newer; Clang's intrinsics headers stay closed without `-mlasx` or `-mcpu=power9`.
Header-only units enable the capabilities their own flags name.