FeenoX: A cloud-first free no-fee no-X uniX-like finite-element(ish) computational engineering tool

- 1 About FeenoX
  - 1.1 Extents
    - 1.1.1 Examples
    - 1.1.2 Tutorials
    - 1.1.3 Tests
  - 1.2 Capabilities
  - 1.3 Usefulness
- 2 Documentation
- 3 Quickstart
  - 3.1 Install from apt
  - 3.2 Download
  - 3.3 Git repository
- 4 Licensing
  - 4.1 Contributing
- 5 Further information

[DOI]

  [1 About FeenoX]: #about-feenox
  [1.1 Extents]: #extents
  [1.1.1 Examples]: #examples
  [1.1.2 Tutorials]: #tutorials
  [1.1.3 Tests]: #tests
  [1.2 Capabilities]: #capabilities
  [1.3 Usefulness]: #usefulness
  [2 Documentation]: #documentation
  [3 Quickstart]: #quickstart
  [3.1 Install from apt]: #install-from-apt
  [3.2 Download]: #download
  [3.3 Git repository]: #git-repository
  [4 Licensing]: #licensing
  [4.1 Contributing]: #sec:contributing
  [5 Further information]: #further-information
  [DOI]: https://joss.theoj.org/papers/10.21105/joss.05846/status.svg
  [1]: https://doi.org/10.21105/joss.05846

About FeenoX

FeenoX is a cloud-first free and open source tool to solve
engineering-related problems using a computer (or many computers in
parallel) with a particular design basis.

Consider the following input file:

    PROBLEM mechanical MESH box.msh

    T(x,y,z) = sqrt(x^2 + y^2) + z   # non-trivial temperature distribution
    E = 200e3 * (1-T(x,y,z)/300)     # temperature-dependent Young modulus
    nu = 0.3

    BC left fixed           # left face fully fixed
    BC top  p=1e4*(1+x)     # top face with a triapezoidal load

    WRITE_RESULTS FORMAT vtu

Note that

- The input file is made of simple self-descriptive English keywords
- Material properties and boundary conditions can be expressions of x, y
  and z
- Input mesh is is Gmsh’s format .msh
- Output results are in Paraview’s .vtk/.vtu formats

Each of these items has a lot of design and usage implications,
thoroughly discussed in the Software Design Specification, ranging from
integrating FeenoX as a back end for different front ends with a
reasonably low effort (e.g. SunCAE), down to suitability for interaction
with Large Language Models. As a reference, the reader is encouraged to
compare the above input syntax with any other FEA solver and then
consider how to ask ChatGPT & friends for help to create an input file
from scratch. Or how to write a Graphical User Interface that would need
to create something the solver can read. Plus, it can be installed with

    apt install feenox

------------------------------------------------------------------------

Choose your background for further details about the what, how and whys:

- Industry Engineer
- Unix Hacker
- Academic Professor

See the following paper for a brief summary (and to cite FeenoX in your
work):

- Theler J, “FeenoX: a cloud-first finite-element(ish) computational
  engineering tool,” Journal of Open Source Software, vol. 9, no. 95,
  p. 5846, Mar. 2024, doi: 10.21105/joss.05846.

  News

  - First non-trivial large-deformation mechanical example: NAFEMS GNL5
    “Large-deformation beam”

  - 

    FeenoX is now in Debian (testing) and Ubuntu 25.04!

        You can install FeenoX from APT

            sudo apt install feenox

        Check progress on the following pages:

        - https://packages.debian.org/unstable/science/feenox
        - https://launchpad.net/ubuntu/+source/feenox

  - 

    Open-source web-based UX for FeenoX.

        Take a look at SunCAE for an example of how to write a front end
        for FeenoX.

  - 

    IB students

        Remember that your first read should be the 0-th tutorial,
        Setting up your workspace

  [FeenoX]: https://seamplex.com/feenox
  [cloud-first]: https://seamplex.com/feenox/doc/sds.html#cloud-first
  [free and open source]: #licensing
  [engineering-related problems]: #extents
  [many computers in parallel]: https://www.seamplex.com/feenox/doc/sds.html#sec:scalability
  [particular design basis]: https://seamplex.com/feenox/doc/sds.html
  [input file]: https://www.seamplex.com/feenox/doc/sds.html#sec:input
  [simple]: https://www.seamplex.com/feenox/doc/sds.html#sec:simple
  [self-descriptive English]: https://www.seamplex.com/feenox/doc/sds.html#sec:sugar
  [keywords]: https://www.seamplex.com/feenox/doc/sds.html#sec:nouns_verbs
  [Material properties and boundary conditions]: https://www.seamplex.com/feenox/doc/sds.html#sec:flexibility
  [expressions of x, y and z]: https://www.seamplex.com/feenox/doc/sds.html#sec:expression
  [Gmsh’s format .msh]: https://www.seamplex.com/feenox/doc/sds.html#sec:interoperability
  [Software Design Specification]: https://www.seamplex.com/feenox/doc/sds.html
  [SunCAE]: https://www.seamplex.com/suncae
  [Industry Engineer]: ./README4engineers.md
  [Unix Hacker]: ./README4hackers.md
  [Academic Professor]: ./README4academics.md
  [cite FeenoX in your work]: ./doc/FAQ.md#how-should-i-cite-feenox
  [10.21105/joss.05846]: https://doi.org/10.21105/joss.05846
  [NAFEMS GNL5 “Large-deformation beam”]: https://www.seamplex.com/feenox/examples/mechanical.html#nafems-gnl5-large-deformation-beam
  [Setting up your workspace]: https://www.seamplex.com/feenox/doc/tutorials/000-setup/

Extents

Examples

- Basic mathematics
- Systems of ODEs/DAEs
- Laplace’s equation
- Heat conduction
- Elasticity (small and large strain)
- Modal analysis
- Neutron diffusion
- Neutron SN

  [Basic mathematics]: https://seamplex.com/feenox/examples/basic.html
  [Systems of ODEs/DAEs]: https://seamplex.com/feenox/examples/daes.html
  [Laplace’s equation]: https://seamplex.com/feenox/examples/laplace.html
  [Heat conduction]: https://seamplex.com/feenox/examples/thermal.html
  [Elasticity (small and large strain)]: https://seamplex.com/feenox/examples/mechanical.html
  [Modal analysis]: https://seamplex.com/feenox/examples/modal.html
  [Neutron diffusion]: https://seamplex.com/feenox/examples/neutron_diffusion.html
  [Neutron SN]: https://seamplex.com/feenox/examples/neutron_sn.html

Tutorials

0.  Setting up your workspace
1.  Overview: the tensile test case
2.  Fun & games: solving mazes with PDES instead of AI
3.  Heat conduction

  [2]: https://www.seamplex.com/feenox/doc/tutorials/000-setup
  [Overview: the tensile test case]: https://www.seamplex.com/feenox/doc/tutorials/110-tensile-test
  [Fun & games: solving mazes with PDES instead of AI]: https://www.seamplex.com/feenox/doc/tutorials/120-mazes
  [3]: https://www.seamplex.com/feenox/doc/tutorials/320-thermal

Tests

The tests directory in the repository has hundreds of

- grep-able examples
- unit and regression tests,
- (crude) mathematical & code verification tests (as in “are we solving
  right the equations?”),
- subdirectories with further case studies
  - mms
    - thermal
      - 2d
      - 3d
    - mechanical
      - sdef
      - ldef
  - nafems
    - le10

  [tests]: https://github.com/seamplex/feenox/tree/main/tests
  [unit and regression tests]: https://seamplex.com/feenox/doc/compilation.html#sec:test-suite
  [mms]: https://github.com/seamplex/feenox/tree/main/tests/mms
  [thermal]: https://github.com/seamplex/feenox/tree/main/tests/mms/thermal
  [2d]: https://github.com/seamplex/feenox/tree/main/tests/mms/thermal/2d
  [3d]: https://github.com/seamplex/feenox/tree/main/tests/mms/thermal/3d
  [mechanical]: https://github.com/seamplex/feenox/tree/main/tests/mms/mechanical
  [sdef]: https://github.com/seamplex/feenox/tree/main/tests/mms/thermal/sdef
  [ldef]: https://github.com/seamplex/feenox/tree/main/tests/mms/thermal/ldef
  [nafems]: https://github.com/seamplex/feenox/tree/main/tests/nafems
  [le10]: https://github.com/seamplex/feenox/tree/main/tests/nafems/le10

Capabilities

- Both free as in “free speech” and in “free beer”
- The problem to solve is defined through a syntactically-sugared
  self-descriptive English-like plain-text input file that should
  resemble the original human-friendly problem formulation as much as
  possible:
  - no need to recompile if the problem changes (FeenoX is a program,
    not a library)
  - nouns are definitions and verbs are instructions
  - simple problems need simple inputs
  - everything is an expression
  - 100%-defined user output (no PRINT nor WRITE_RESULTS instructions,
    no output)
- Cloud-first design (cloud friendliness is not enough)
- MPI parallelization
- Leverages high-quality well-established free and open source libraries
  to solve…
  - general mathematical problems using GNU GSL
  - sets of ODEs/DAEs using SUNDIALS
  - PDEs formulated with the finite element method
    - reads mesh in Gmsh format
    - uses PETSc/SLEPc to solve
      - linear systems (KSP)
      - non-linear systems (SNES)
      - time-dependent systems (TS)
      - generalized eigen-value problems (EPS)
    - writes results in Gmsh’s .msh format and/or Paraview’s VTU/VTK
      formats
- Focuses on flexibility, especially when defining non-uniform
  multi-solid material properties from ASME tables
- Follows the Unix programming philosophy
  - rule of separation
  - rule of silence
  - rule of economy
- Each PDE (i.e. from Laplace downward in the list of examples) is
  implemented in a subdirectory within src/pde of the source tree
  - any subdirectory can be removed if a particular PDE is not needed
  - any subdirectory can be used as a template to add a new PDE to the
    capabilities
- Space, time and/or solution-dependent material properties and boundary
  conditions
  - algebraic expressions, and/or
  - point-wise interpolated data
- Command-line argument expansion for
  - increased flexibility,
  - parametric sweeps, and/or
  - optimization loops
- Steady-state, [quasi-static] and/or transient problems
- Linear and non-linear problems
- Possibility to verify the code using the Method of Manufactured
  Solutions
- Separate repository to profile and study code performance using
  Google’s benchmark library

  [problem]: https://www.seamplex.com/feenox/doc/feenox-manual.html#problem
  [syntactically-sugared]: https://seamplex.com/feenox/doc/sds.html#sec:syntactic
  [self-descriptive English-like plain-text input file]: https://seamplex.com/feenox/doc/sds.html#sec:input
  [resemble the original human-friendly problem formulation]: https://seamplex.com/feenox/doc/sds.html#sec:matching-formulations
  [no need to recompile if the problem changes]: https://seamplex.com/feenox/doc/sds.html#sec:introduction
  [nouns are definitions and verbs are instructions]: https://seamplex.com/feenox/doc/sds.html#sec:nouns_verbs
  [simple problems need simple inputs]: https://seamplex.com/feenox/doc/sds.html#sec:simple
  [everything is an expression]: https://seamplex.com/feenox/doc/sds.html#sec:expression
  [100%-defined user output]: https://seamplex.com/feenox/doc/sds.html#sec:output
  [WRITE_RESULTS]: https://www.seamplex.com/feenox/doc/feenox-manual.html#write_results
  [Cloud-first design]: https://seamplex.com/feenox/doc/sds.html#cloud-first
  [MPI parallelization]: https://seamplex.com/feenox/doc/sds.html#sec:scalability
  [general mathematical problems]: https://seamplex.com/feenox/examples/basic.html
  [GNU GSL]: https://www.gnu.org/software/gsl/
  [sets of ODEs/DAEs]: https://seamplex.com/feenox/examples/daes.html
  [SUNDIALS]: https://computing.llnl.gov/projects/sundials
  [PDEs]: https://github.com/seamplex/feenox/tree/main/src/pdes
  [finite element method]: https://en.wikipedia.org/wiki/Finite_element_method
  [Gmsh]: http://gmsh.info/
  [PETSc]: https://petsc.org/release/
  [SLEPc]: https://slepc.upv.es/
  [KSP]: https://petsc.org/release/manual/ksp/
  [SNES]: https://petsc.org/release/manual/snes/
  [TS]: https://petsc.org/release/manual/ts/
  [EPS]: https://slepc.upv.es/documentation/current/docs/manualpages/EPS/index.html
  [.msh]: http://gmsh.info/doc/texinfo/gmsh.html#MSH-file-format
  [Paraview]: https://www.paraview.org/
  [VTU/VTK]: https://docs.vtk.org/en/latest/design_documents/VTKFileFormats.html
  [flexibility]: https://seamplex.com/feenox/doc/sds.html#sec:flexibility
  [non-uniform multi-solid material properties from ASME tables]: https://www.seamplex.com/feenox/doc/tutorials/320-thermal/#from-a-steady-state
  [Unix programming philosophy]: https://seamplex.com/feenox/doc/sds.html#sec:unix
  [rule of separation]: https://seamplex.com/feenox/doc/sds.html#sec:separation
  [rule of silence]: https://seamplex.com/feenox/doc/sds.html#sec:silence
  [rule of economy]: https://seamplex.com/feenox/doc/sds.html#sec:economy
  [is implemented in a subdirectory]: https://seamplex.com/feenox/doc/sds.html#sec:extensibility
  [Space]: https://github.com/seamplex/feenox/blob/main/tests/thermal-two-squares-material-explicit-space.fee
  [time]: https://github.com/seamplex/feenox/blob/main/tests/nafems-t3-1d.fee
  [material properties]: https://github.com/seamplex/feenox/blob/main/tests/wilson-2d.fee
  [boundary conditions]: https://github.com/seamplex/feenox/blob/main/tests/radiation-as-convection-celsius.fee
  [algebraic expressions]: https://seamplex.com/feenox/examples/mechanical.html#parallelepiped-whose-youngs-modulus-is-a-function-of-the-temperature
  [point-wise interpolated data]: https://seamplex.com/feenox/examples/mechanical.html#temperature-dependent-material-properties
  [Command-line argument expansion]: https://seamplex.com/feenox/doc/sds.html#sec:run-time-arguments
  [increased flexibility]: https://seamplex.com/feenox/examples/basic.html#computing-the-derivative-of-a-function-as-a-unix-filter
  [parametric sweeps]: https://seamplex.com/feenox/doc/sds.html#sec:parametric
  [optimization loops]: https://seamplex.com/feenox/doc/sds.html#optimization-loops
  [Steady-state]: https://www.seamplex.com/feenox/doc/tutorials/120-mazes/#solving-the-steady-state-laplace-equation
  [transient problems]: https://www.seamplex.com/feenox/doc/tutorials/320-thermal/#sec:transient
  [Linear]: https://www.seamplex.com/feenox/doc/tutorials/320-thermal/#linear-steady-state-problems
  [non-linear]: https://www.seamplex.com/feenox/doc/tutorials/320-thermal/#non-linear-state-state-problems
  [Method of Manufactured Solutions]: https://github.com/seamplex/feenox/tree/main/tests/mms
  [repository to profile and study code performance]: https://github.com/seamplex/feenox-benchmark
  [Google’s benchmark library]: https://github.com/google/benchmark

Usefulness

- CAEplex: a web-based thermo-mechanical solver running on the cloud
- Non-conformal mesh mapping
- ASME stress linearization for pressurized pipes and vessels
- Assessment of material properties from tabulated sources
- Environmentally-assisted fatigue analysis in dissimilar interfaces of
  nuclear pipes
- Neutron transport in the cloud
- Solving mazes without AI
- Parametric NAFEMS LE10 benchmark: comparison of resource consumption
  for different FEA programs
- Some Youtube videos

  [CAEplex]: https://www.caeplex.com
  [web-based thermo-mechanical solver running on the cloud]: https://www.youtube.com/watch?v=DOnoXo_MCZg
  [Non-conformal mesh mapping]: https://github.com/gtheler/feenox-non-conformal-mesh-interpolation
  [ASME stress linearization for pressurized pipes and vessels]: https://github.com/seamplex/pipe-linearize
  [Assessment of material properties from tabulated sources]: https://seamplex.com/feenox/examples/basic.html#on-the-evaluation-of-thermal-expansion-coefficients
  [Environmentally-assisted fatigue analysis in dissimilar interfaces of nuclear pipes]:
    https://github.com/seamplex/piping-asme-fatigue
  [Neutron transport in the cloud]: https://seamplex.com/thesis/html/front/abstract.html
  [Solving mazes without AI]: https://www.linkedin.com/feed/update/urn:li:activity:6973982270852325376/
  [Parametric NAFEMS LE10 benchmark: comparison of resource consumption for different FEA programs]:
    https://seamplex.com/feenox/tests/nafems/le10/
  [Some Youtube videos]: https://seamplex.com/feenox/doc/#sec:youtube

Documentation

Browse through the documentation index and/or the doc subdirectory of
the Github repository for

- FAQs, including what FeenoX means
- Manual
- Description
- Software Design Requirements
- Software Design Specification
- Unix man page (accessible through man feenox after installation)
- History
- Compilation guide
- Programming guide

  [documentation index]: doc
  [doc]: https://github.com/seamplex/feenox/tree/main/doc
  [Github repository]: https://github.com/seamplex/feenox/
  [FAQs]: ./doc/FAQ.md
  [what FeenoX means]: https://seamplex.com/feenox/doc/FAQ.html#what-does-feenox-mean
  [Manual]: https://seamplex.com/feenox/doc/feenox-manual.html
  [Description]: https://www.seamplex.com/feenox/doc/feenox-desc.html
  [Software Design Requirements]: https://seamplex.com/feenox/doc/srs.html
  [4]: https://seamplex.com/feenox/doc/sds.html
  [Unix man page]: https://seamplex.com/feenox/doc/feenox.1.html
  [History]: ./doc/history.md
  [Compilation guide]: ./doc/compilation.md
  [Programming guide]: ./doc/programming.md

Quickstart

Install from apt

If you use Debian (either Sid, or Trixie with backports) or Ubuntu 25.04
or higher, you can do

    sudo apt install feenox

See these links for details about the packages:

- https://packages.debian.org/unstable/science/feenox
- https://launchpad.net/ubuntu/+source/feenox

  [Debian]: https://www.debian.org
  [Sid]: https://wiki.debian.org/DebianUnstable
  [Trixie]: https://www.debian.org/releases/trixie
  [backports]: https://backports.debian.org
  [Ubuntu 25.04]: https://releases.ubuntu.com/plucky

Download

  ----------------------------- -----------------------------------------------------
  Debian package                https://packages.debian.org/unstable/science/feenox

  Ubuntu package                https://launchpad.net/ubuntu/+source/feenox

  GNU/Linux binaries            https://www.seamplex.com/feenox/dist/linux

  Source tarballs               https://www.seamplex.com/feenox/dist/src

  Github repository             https://github.com/seamplex/feenox/
  ----------------------------- -----------------------------------------------------

Generic GNU/Linux binaries are provided as statically-linked executables
for convenience. They do not support MUMPS nor MPI and have only basic
optimization flags. Please compile from source for high-end
applications. See detailed compilation instructions.

  - Be aware that FeenoX does not have a GUI. Read the documentation,
    especially the description and the FAQs. Ask for help on the GitHub
    discussions page if you do now understand what this means.

  - You can still use FeenoX through a web-based UI through SunCAE.

  [detailed compilation instructions]: doc/compilation.md
  [documentation]: https://seamplex.com/feenox/doc/
  [description]: https://www.seamplex.com/feenox/doc/feenox-desc.html
  [5]: https://seamplex.com/feenox/doc/FAQ.html
  [GitHub discussions page]: https://github.com/seamplex/feenox/discussions
  [SunCAE]: https://www.seamplex.com/suncae

Git repository

The Git repository has the latest sources repository. To compile,
proceed as follows. If something goes wrong and you get an error, do not
hesitate to ask in FeenoX’s discussion page.

  If you do not have Git or Autotools, download a source tarball and
  proceed with the usual configure & make procedure. See these
  instructions.

1.  Install mandatory dependencies

        sudo apt-get update
        sudo apt-get install git build-essential make automake autoconf libgsl-dev

    If you cannot install libgsl-dev but still have git and the build
    toolchain, you can have the configure script to download and compile
    it for you. See point 4 below.

2.  Install optional dependencies (of course these are optional but
    recommended)

        sudo apt-get install libsundials-dev petsc-dev slepc-dev

3.  Clone Github repository

        git clone https://github.com/seamplex/feenox

4.  Bootstrap, configure, compile & make

        cd feenox
        ./autogen.sh
        ./configure
        make -j4

    If you cannot (or do not want to) use libgsl-dev from a package
    repository, call configure with --enable-download-gsl:

        ./configure --enable-download-gsl

    If you do not have Internet access, get the tarball manually, copy
    it to the same directory as configure and run again. See the
    detailed compilation instructions for an explanation.

5.  Run test suite (optional)

        make check

6.  Install the binary system wide (optional)

        sudo make install

      If you do not have root permissions, configure with your home
      directory as prefix and then make install as a regular user:

          ./configure --prefix=$HOME
          make
          make install

To stay up to date, pull and then autogen, configure and make (and
optionally install):

    git pull
    ./autogen.sh
    ./configure
    make -j4
    sudo make install

See the download page and the compilation guide for detailed
information.

  [discussion page]: https://github.com/seamplex/feenox/discussions
  [source tarball]: https://seamplex.com/feenox/dist/src/
  [these instructions]: doc/source.md
  [6]: compilation.md
  [download page]: https://seamplex.com/feenox/download.html
  [compilation guide]: ./doc/compilation.md

Licensing

FeenoX is distributed under the terms of the GNU General Public License
version 3 or (at your option) any later version. The following text was
borrowed from the Gmsh documentation. Replacing “Gmsh” with “FeenoX”
(using Unix’s sed) gives:

  FeenoX is “free software”; this means that everyone is free to use it
  and to redistribute it on a free basis. FeenoX is not in the public
  domain; it is copyrighted and there are restrictions on its
  distribution, but these restrictions are designed to permit everything
  that a good cooperating citizen would want to do. What is not allowed
  is to try to prevent others from further sharing any version of FeenoX
  that they might get from you.

  Specifically, we want to make sure that you have the right to give
  away copies of FeenoX, that you receive source code or else can get it
  if you want it, that you can change FeenoX or use pieces of FeenoX in
  new free programs, and that you know you can do these things.

  To make sure that everyone has such rights, we have to forbid you to
  deprive anyone else of these rights. For example, if you distribute
  copies of FeenoX, you must give the recipients all the rights that you
  have. You must make sure that they, too, receive or can get the source
  code. And you must tell them their rights.

  Also, for our own protection, we must make certain that everyone finds
  out that there is no warranty for FeenoX. If FeenoX is modified by
  someone else and passed on, we want their recipients to know that what
  they have is not what we distributed, so that any problems introduced
  by others will not reflect on our reputation.

  The precise conditions of the license for FeenoX are found in the
  General Public License that accompanies the source code. Further
  information about this license is available from the GNU Project
  webpage http://www.gnu.org/copyleft/gpl-faq.html.

FeenoX is licensed under the terms of the GNU General Public License
version 3 or, at the user convenience, any later version. This means
that users get the four essential freedoms:[1]

0.  The freedom to run the program as they wish, for any purpose.
1.  The freedom to study how the program works, and change it so it does
    their computing as they wish.
2.  The freedom to redistribute copies so they can help others.
3.  The freedom to distribute copies of their modified versions to
    others.

So a free program has to be open source, but it also has to explicitly
provide the four freedoms above both through the written license and
through appropriate mechanisms to get, modify, compile, run and document
these modifications using well-established and/or reasonable
straightforward procedures. That is why licensing FeenoX as GPLv3+ also
implies that the source code and all the scripts and makefiles needed to
compile and run it are available for anyone that requires it (i.e. it is
compiled with ./configure && make). Anyone wanting to modify the program
either to fix bugs, improve it or add new features is free to do so. And
if they do not know how to program, the have the freedom to hire a
programmer to do it without needing to ask permission to the original
authors. Even more, the documentation is released under the terms of the
Creative Commons Attribution-ShareAlike 4.0 International License so
these new (or modified) features can be properly documented as well.

Nevertheless, since these original authors are the copyright holders,
they still can use it to either enforce or prevent further actions from
the users that receive FeenoX under the GPLv3+. In particular, the
license allows re-distribution of modified versions only if

a.  they are clearly marked as different from the original, and
b.  they are distributed under the same terms of the GPLv3+.

There are also some other subtle technicalities that need not be
discussed here such as

- what constitutes a modified version (which cannot be redistributed
  under a different license)
- what is an aggregate (in which each part be distributed under
  different licenses)
- usage over a network and the possibility of using AGPL instead of GPL
  to further enforce freedom

These issues are already taken into account in the FeenoX licensing
scheme.

It should be noted that not only is FeenoX free and open source, but
also all of the libraries it depends on (and their dependencies) also
are. It can also be compiled using free and open source build tool
chains running over free and open source operating systems.

[1]  There are some examples of pieces of computational software which
are described as “open source” in which even the first of the four
freedoms is denied. The most iconic case is that of Android, whose
sources are readily available online but there is no straightforward way
of updating one’s mobile phone firmware with a customized version, not
to mention vendor and hardware lock ins and the possibility of bricking
devices if something unexpected happens. In the nuclear industry, it is
the case of a Monte Carlo particle-transport program that requests users
to sign an agreement about the objective of its usage before allowing
its execution. The software itself might be open source because the
source code is provided after signing the agreement, but it is not free
(as in freedom) at all.

  [GNU General Public License]: http://www.gnu.org/copyleft/gpl.html
  [Gmsh documentation]: http://gmsh.info/doc/texinfo/gmsh.html#Copying-conditions
  [General Public License]: https://github.com/seamplex/feenox/blob/master/COPYING
  [7]: https://www.gnu.org/licenses/gpl-3.0
  [the documentation]: https://seamplex.com/feenox/doc/
  [Creative Commons Attribution-ShareAlike 4.0 International License]: https://creativecommons.org/licenses/by-sa/4.0/
  [AGPL]: https://en.wikipedia.org/wiki/GNU_Affero_General_Public_License

Contributing

Contributions from hackers and/or academics are welcome, especially new
types of PDEs and new formulations of existing PDEs. For elliptic
operators feel free to use the Laplace equation at src/pdes/laplace as a
template.

1.  Read the Programming Guide.
2.  Browse Github discussions and open a new thread explaining what you
    want to do and/or asking for help.
3.  Fork the Git repository under your Github account
4.  Create a pull request, including
    - code,
    - documentation, and
    - tests.
5.  Follow up the review procedure.

Note that

- It is mandatory to observe the Code of Conduct.
- The contributed code has to be compatible with the GPLv3+ license.
- Each author keeps the copyright of the contribution.
- You can ask!

  [hackers]: README4hackers.html
  [academics]: README4academics.html
  [src/pdes/laplace]: https://github.com/seamplex/feenox/tree/main/src/pdes/laplace
  [8]: https://seamplex.com/feenox/doc/programming.html
  [Github discussions]: https://github.com/seamplex/feenox/discussions
  [Git repository]: https://github.com/seamplex/feenox/
  [Code of Conduct]: https://seamplex.com/feenox/doc/CODE_OF_CONDUCT.html
  [GPLv3+ license]: https://www.seamplex.com/feenox/#sec:licensing

Further information

Home page: https://www.seamplex.com/feenox
Repository: https://github.com/seamplex/feenox
Bug reporting: https://github.com/seamplex/feenox/issues
Discussions: https://github.com/seamplex/feenox/discussions
Follow us: YouTube LinkedIn Github

------------------------------------------------------------------------

FeenoX is licensed under GNU GPL version 3 or (at your option) any later
version.
FeenoX is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

  [YouTube]: https://www.youtube.com/channel/UCC6SzVLxO8h6j5rLlfCQPhA
  [LinkedIn]: https://www.linkedin.com/company/seamplex/
  [Github]: https://github.com/seamplex
  [GNU GPL version 3]: http://www.gnu.org/copyleft/gpl.html