momwire 0.2.3

A pure-Python method-of-moments antenna simulator with optional C++ accelerators

momwire

A pure-Python method-of-moments antenna simulator with optional C++ accelerators (pybind11).

Extracted from antenna_designer.

Install

python3 -m venv .venv
source .venv/bin/activate
pip install --upgrade pip
pip install -e .

macOS: the C++ accelerator uses Homebrew's OpenMP runtime, so brew install libomp is required — both to compile from source and to run the prebuilt Apple-Silicon wheel. The wheel deliberately does not bundle libomp (it links Homebrew's by absolute path) so that it shares a single OpenMP runtime with pynec-accel; two private copies in one process abort with OMP: Error #15 (or deadlock). Without libomp installed, the accelerator can't load and momwire warns and falls back to the slower pure-Python path. On Linux the system libgomp covers this, so no extra step is needed.

Test

pip install -e ".[test]"   # core + test deps (pytest, matplotlib, scikit-rf)
pytest tests/

The cross-validation against NEC2 (tests/test_pynec_backend.py) additionally needs PyNEC — a test-only dependency installed separately from a wheel (see below). Those tests skip cleanly when it isn't present; everything else runs without it.

Optional: PyNEC backend (test-only)

momwire can be cross-validated against NEC2 via PyNEC (the tests/test_pynec_backend.py suite); NEC2 also delivers ~5–10× faster single-frequency solves. PyNEC is a test-flow-only dependency — momwire's own solver never imports it.

Install the PyNEC wheel

Install PyNEC from the python-necpp fork's release. The wheels are self-contained — OpenBLAS is vendored (via scipy-openblas32), so no system BLAS, SWIG, or build toolchain is needed — and cover Linux + Windows on CPython 3.10–3.14:

pip install PyNEC --no-index \
    --find-links https://github.com/stevenmburns/python-necpp/releases/expanded_assets/v1.7.4-accel.1

--no-index ensures pip takes the fork's wheel rather than upstream PyNEC on PyPI (same version, but its builds are broken on current Python and it lacks the OpenBLAS/OpenMP work). After install, from PyNEC import nec_context works and the cross-validation tests run; without it they're skipped (momwire itself needs no PyNEC).

Runtime thread pinning

The wheel links OpenBLAS and parallelises the NEC2 matrix fill with OpenMP. Pick thread counts up front:

export OMP_NUM_THREADS=$(nproc --all)   # PyNEC matrix fill
export OPENBLAS_NUM_THREADS=1           # muzzle numpy/scipy's idle pool

Pinning OPENBLAS_NUM_THREADS=1 stops numpy/scipy from spinning up their own OpenBLAS thread pool that contends with PyNEC's threads on the same cores. On a 100-director Yagi (2142 segs) this is worth ~8% wall time at NP=4.