Spacetime Tents in NGSolve

This NGS-Tents (ngstents) package is a c++ extension of the NGSolve finite element library, designed to ease experimentation with solvers based on spacetime tents for hyperbolic systems. A python front-end allows new equations (linear or nonlinear conservation laws) to be solved by easily defining required fluxes and numerical fluxes in a few lines of code.

Install

Build using pip

On a computer with a build system (compiler etc), you can install NGS-Tents by

python3 -m pip install git+https://github.com/jayggg/ngstents.git

If you do not have the dependency ngsolve installed, this command will attempt to install ngsolve first, before proceeding to install ngstents. If you prefer to use your own existing install of ngsolve, please use the --no-build-isolation argument:

python3 -m pip install --no-build-isolation git+https://github.com/jayggg/ngstents.git

Build using CMake

If you built ngsolve from source, you can also build and install ngstents in the traditional manner. After cloning this repository, compile the c++ code here and install as follows:

cd src
mkdir build && cd build
cmake -DNGSolve_DIR=<Path2YourNGSolveInstallCMake>  ..
make install

(Often CMake is able to correctly detect the path to your NGSolve installation in which case you do not have to specify the NGSolve_DIR variable.)

Binary install

If you do not have a compiler, then you can install NGS-Tents using a binary installer. To do so on linux, mac, and windows (with python>= 3.9), use the following command.

pip install --pre ngstents

Use

To start using this code's python interface, import the module after installation:

import ngstents

It contains classes named Tent and TentSlab used to partition spacetime into tents. It also has a submodule named conslaw which contains specific pre-programmed hyperbolic equations and also facilities to define and solve new hyperbolic systems using the python interface. Use python's help system to query for documentation on each object. The demo folder contains example scripts. The docs folder contains more documentation, explained next.

Documentation

Read the docs online. This documentation is generated from hands-on style tutorial notebooks in the docs folder.

Offline, to build and test the docs locally, navigate to the ngstents/docs folder and run these:

pip install -r requirements.txt
sphinx-build -b html . _build_docs

You can then open the docs from ngstents/docs/_build_docs/INDEX.html.

Alternately, you can build a jupyter book of the documentation by navigating to the ngstents/docs folder and issuing

jupyter-book build .

which creates documentation in ngstents/docs/_build/INDEX.html.

Check

If you extend the code, your new code changes can be cross-checked against a test suite provided in the 'tests' folder. For example, if you have pytest installed, move to the ngstents/tests folder and use pytest:

pytest .

Organization

• src: c++ source code
• py: python packaging files
• doc: tutorials and explanations
• demo: examples of applications
• tests: test suite