Installation from Source

If nec2++ isn't available precompiled in your system, here are the instructions for building from source code.

Quick Build

nec2++ uses CMake (≥ 3.16). Eigen 5.0.1 is bundled in src/eigen/ — no external libraries are required, just a C++17 compiler and CMake:

cmake -B build
cmake --build build -j4
sudo cmake --install build

This builds the nec2++ and nec2diff command-line tools, the libnecpp static and shared libraries, and installs headers, man pages, and a necpp.pc pkg-config file.

Build options

Pass these on the configure step (e.g. -DNECPP_BUILD_TESTS=OFF):

Option	Default	Effect
CMAKE_BUILD_TYPE	Release	Debug adds -O0 -g; use Release for -O2.
NECPP_BUILD_TESTS	ON	Build the Catch2 unit tests (run with ctest --test-dir build).
NECPP_BUILD_WASM	OFF	Build the Emscripten/WASM target (needs emcmake).
BUILD_SHARED_LIBS	ON	Also build libnecpp.so in addition to libnecpp.a.

Building for debug

cmake -B build -DCMAKE_BUILD_TYPE=Debug
cmake --build build -j4

Bounds checking is enabled in the debug build via NEC_ERROR_CHECK=1 in the test target.

Running the tests

cmake --build build          # builds the test runner
ctest --test-dir build --output-on-failure

Cross-compiling

macOS

CMake works out of the box with Apple Clang:

cmake -B build
cmake --build build -j4

To generate an Xcode project instead:

cmake -B build -G Xcode

If you see a linker error like "file was built for archive which is not the architecture being linked", this is usually caused by Homebrew's binutils conflicting with the system toolchain. Run brew unlink binutils then rebuild. You can re-link binutils afterwards with brew link binutils.

Windows

Cross-compiling from Linux with MinGW

sudo apt install g++-mingw-w64-x86-64      # Debian/Ubuntu
cmake -B build -DCMAKE_C_COMPILER=x86_64-w64-mingw32-gcc \
               -DCMAKE_CXX_COMPILER=x86_64-w64-mingw32-g++
cmake --build build

Older 32-bit MinGW:

cmake -B build -DCMAKE_CXX_COMPILER=i686-w64-mingw32-g++

Visual Studio

CMake's Visual Studio generator replaces the old hand-maintained .vcxproj files:

cmake -B build -G "Visual Studio 17 2022"
cmake --build build --config Release

WASM (Emscripten)

Two ways:

Native emsdk (if you have it installed):

emcmake cmake -B build-wasm -DNECPP_BUILD_WASM=ON -DNECPP_BUILD_TESTS=OFF
cmake --build build-wasm -j4

Docker wrapper (no local emsdk needed):

./scripts/build_wasm_docker.sh

Both produce nec2pp.js + nec2pp.wasm exposing a C API (nec_create_context, nec_process_input, nec_get_output, …).

Using the library from another project

After cmake --install, necpp exposes both pkg-config and a CMake package config. Pick whichever your build system uses.

pkg-config:

pkg-config --cflags --libs necpp

CMake (find_package):

find_package(necpp REQUIRED)
target_link_libraries(my_app PRIVATE necpp::necpp)

Packaging (DEB / RPM / tarball)

CMake's CPack produces split packages (runtime library, development files, command-line tools) replacing the old debian/ directory:

cd build
cpack -G DEB    # libnecpp2, libnecpp-dev, necpp
cpack -G RPM    # needs rpmbuild
cpack -G TXZ    # plain tarball

About Eigen

nec2++ uses Eigen 5.0.1 (bundled in src/eigen/) for all linear algebra — safe arrays, 3-vectors, and LU decomposition. No external Eigen, LAPACK, or BLAS installation is required. The old --with-eigen, --with-lapack, and --with-atlas configure options have been removed.

The ANTLR parser (nec_parse)

The experimental ANTLR 4 NEC parser is built separately (it needs Java + the antlr4 runtime, which are not part of the core CMake build). See antlr/README.md:

make -C antlr          # builds nec_parse via the Emscripten Docker image

Notes for embedding in other projects

Some source files are header-only and have no corresponding .cpp file. If your build system expects a .cpp for every .h, the following files are intentionally header-only and should be included directly:

• math_util.h — math constants and the nec_3vector class
• nec_wire.h — wire intersection geometry
• safe_array.h — bounds-checked array template
• src/eigen/ — bundled Eigen 5.0.1 headers (include via -I src/eigen)