meanas

meanas is a python package for electromagnetic simulations

** UNSTABLE / WORK IN PROGRESS **

Formerly known as fdfd_tools.

This package is intended for building simulation inputs, analyzing simulation outputs, and running short simulations on unspecialized hardware. It is designed to provide tooling and a baseline for other, high-performance purpose- and hardware-specific solvers.

Contents

• Finite difference frequency domain (FDFD)
  • Library of sparse matrices for representing the electromagnetic wave equation in 3D, as well as auxiliary matrices for conversion between fields
  • Waveguide mode operators
  • Waveguide mode eigensolver
  • Stretched-coordinate PML boundaries (SCPML)
  • Functional versions of most operators
  • Anisotropic media (limited to diagonal elements eps_xx, eps_yy, eps_zz, mu_xx, ...)
  • Arbitrary distributions of perfect electric and magnetic conductors (PEC / PMC)
• Finite difference time domain (FDTD)
  • Basic Maxwell time-steps
  • Poynting vector and energy calculation
  • Convolutional PMLs

This package does not provide a fast matrix solver, though by default meanas.fdfd.solvers.generic(...) will call scipy.sparse.linalg.qmr(...) to perform a solve. For 2D FDFD problems this should be fine; likewise, the waveguide mode solver uses scipy's eigenvalue solver, with reasonable results.

For solving large (or 3D) FDFD problems, I recommend a GPU-based iterative solver, such as opencl_fdfd or those included in MAGMA. Your solver will need the ability to solve complex symmetric (non-Hermitian) linear systems, ideally with double precision.

• WIP Source repository
• TODO Source repository
• PyPI TBD

Installation

Requirements:

• python 3 (tests require 3.7)
• numpy
• scipy

Install from PyPI with pip:

pip3 install 'meanas[test,examples]'

Development install

Install python3.7, virtualenv, and git:

# This is for Debian/Ubuntu/other-apt-based systems; you may need an alternative command
sudo apt install python3.7 virtualenv build-essential python3.7-dev git

If python 3.7 is not your default python3 version, create a virtualenv:

# Check python3 version:
python3 --version
# output on my system: Python 3.7.5rc1
# If this indicates a version >= 3.7, you can skip all
#  the steps involving virtualenv or referencing the venv/ directory

# Create a virtual environment using python3.7 and place it in the directory `venv/`
virtualenv -p python3.7 venv

In-place development install:

# Download using git
git clone --branch wip https://mpxd.net/code/jan/fdfd_tools.git meanas/

# NOTE: In the future this will become
#git clone https://mpxd.net/code/jan/meanas.git

# If you are using a virtualenv, activate it
source venv/bin/activate

# Install in-place (-e, editable) from ./meanas, including testing and example dependencies ([test, examples])
pip3 install --user -e './meanas[test,examples]'

# Run tests
cd meanas
python3 -m pytest -rsxX | tee test_results.txt

See also:

• git book
• virtualenv documentation
• python language reference
• python standard library

Use

See examples/ for some simple examples; you may need additional packages such as gridlock to run the examples.