Compilation instructions

These detailed compilation instructions are aimed at amd64 Debian-based GNU/Linux distributions. The compilation procedure follows POSIX, so it should work in other operating systems and architectures as well. Distributions not using apt for packages (i.e. yum) should change the package installation commands (and possibly the package names). The instructions should also work for in MacOS, although the apt-get commands should be replaced by brew or similar. Same for Windows under Cygwin, the packages should be installed through the Cygwin installer. WSL was not tested, but should work as well.

1 Quickstart

Note that the quickest way to get started is to get an already-compiled statically-linked binary executable. Follow these instructions if that option is not suitable for your workflow.

On a GNU/Linux box (preferably Debian-based), follow these quick steps. See next section for detailed explanations.

To compile the Git repository, proceed as follows. This procedure does need git and autoconf but new versions can be pulled and recompiled easily.

  1. Install mandatory dependencies

    sudo apt-get install gcc make git 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
  4. Boostrap, configure, compile & make

    cd feenox
    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.

  5. Run test suite (optional)

    make check
  6. Install the binary system wide (optional)

    sudo make install

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

git pull
./; ./configure; make -j4
sudo make install

2 Detailed configuration and compilation

The main target and development environment is Debian GNU/Linux, although it should be possible to compile FeenoX in any free GNU/Linux variant (and even the in non-free MacOS and Windows). As per the SRS, all dependencies have to be available on mainstream GNU/Linux distributions. But they can also be compiled from source in case the package repositories are not available or customized compilation flags are needed (i.e. optimization or debugging settings).

All the dependencies are free and open source software. PETSc/SLEPc also depend on other mathematical libraries to perform particular operations such as linear algebra. These extra dependencies can be either free (such as LAPACK) or non-free (such as MKL), but there is always at least one combination of a working setup that involves only free and open source software which is compatible with FeenoX licensing terms (GPLv3+). See the documentation of each package for licensing details.

2.1 Mandatory dependencies

FeenoX has one mandatory dependency for run-time execution and the standard build toolchain for compilation. It is written in C99 so only a C compiler is needed, although make is also required. Free and open source compilers are favored. The usual C compiler is gcc but clang can also be used. Nevertheless, the non-free icc has also been tested.

Note that there is no need to have a Fortran nor a C++ compiler to build FeenoX. They might be needed to build other dependencies (such as PETSc), but not to compile FeenoX with all the dependencies installed from package repositories. In case the build toolchain is not already installed, do so with

sudo apt-get install gcc make

If the source is to be fetched from the Git repository then of course git is needed but also autoconf and automake since the configure script is not stored in the Git repository but the script that bootstraps the tree and creates it. So if instead of compiling a source tarball one wants to clone from GitHub, these packages are also mandatory:

sudo apt-get install git automake autoconf

Again, chances are that any existing GNU/Linux box has all these tools already installed.

2.1.1 The GNU Scientific Library

The only run-time dependency is GNU GSL (not to be confused with Microsoft GSL). It can be installed with

sudo apt-get install libgsl-dev

In case this package is not available or you do not have enough permissions to install system-wide packages, there are two options.

  1. Pass the option --enable-download-gsl to the configure script below.
  2. Manually download, compile and install GNU GSL

If the configure script cannot find both the headers and the actual library, it will refuse to proceed. Note that the FeenoX binaries already contain a static version of the GSL so it is not needed to have it installed in order to run the statically-linked binaries.

2.2 Optional dependencies

FeenoX has three optional run-time dependencies. It can be compiled without any of these but functionality will be reduced:

  • SUNDIALS provides support for solving systems of ordinary differential equations (ODEs) or differential-algebraic equations (DAEs). This dependency is needed when running inputs with the PHASE_SPACE keyword.

  • PETSc provides support for solving partial differential equations (PDEs). This dependency is needed when running inputs with the PROBLEM keyword.

  • SLEPc provides support for solving eigen-value problems in partial differential equations (PDEs). This dependency is needed for inputs with PROBLEM types with eigen-value formulations such as modal and neutron_transport.

In absence of all these, FeenoX can still be used to

  • solve general mathematical problems such as the ones to compute the Fibonacci sequence,
  • operate on functions, either algebraically or point-wise interpolated,
  • read, operate over and write meshes,
  • etc.

These optional dependencies have to be installed separately. There is no option to have configure to download them as with --enable-download-gsl.


SUNDIALS is a SUite of Nonlinear and DIfferential/ALgebraic equation Solvers. It is used by FeenoX to solve dynamical systems casted as DAEs with the keyword PHASE_SPACE, like the Lorenz system.

Install either by doing

sudo apt-get install libsundials-dev

or by following the instructions in the documentation.

2.2.2 PETSc

The Portable, Extensible Toolkit for Scientific Computation, pronounced PET-see (/ˈpɛt-siː/), is a suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations. It is used by FeenoX to solve PDEs with the keyword PROBLEM, like thermal conduction on a slab.

Install either by doing

sudo apt-get install petsc-dev

or by following the instructions in the documentation.

Note that

  • Configuring and compiling PETSc from scratch might be difficult the first time. It has a lot of dependencies and options. Read the official documentation for a detailed explanation.
  • There is a huge difference in efficiency between using PETSc compiled with debugging symbols and with optimization flags. Make sure to configure --with-debugging=0 for FeenoX production runs and leave the debugging symbols (which is the default) for development only.
  • FeenoX needs PETSc to be configured with real double-precision scalars. It will compile but will complain at run-time when using complex and/or single or quad-precision scalars.
  • FeenoX honors the PETSC_DIR and PETSC_ARCH environment variables when executing configure. If these two do not exist or are empty, it will try to use the default system-wide locations (i.e. the petsc-dev package).

2.2.3 SLEPc

The Scalable Library for Eigenvalue Problem Computations, is a software library for the solution of large scale sparse eigenvalue problems on parallel computers. It is used by FeenoX to solve PDEs with the keyword PROBLEM that need eigen-value computations, such as modal analysis of a cantilevered beam.

Install either by doing

sudo apt-get install slepc-dev

or by following the instructions in the documentation.

Note that

  • SLEPc is an extension of PETSc so the latter has to be already installed and configured.
  • FeenoX honors the SLEPC_DIR environment variable when executing configure. If it does not exist or is empty it will try to use the default system-wide locations (i.e. the slepc-dev package).
  • If PETSc was configured with --download-slepc then the SLEPC_DIR variable has to be set to the directory inside PETSC_DIR where SLEPc was cloned and compiled.

2.3 FeenoX source code

There are two ways of getting FeenoX’ source code:

  1. Cloning the GitHub repository at
  2. Downloading a source tarball from

2.3.1 Git repository

The main Git repository is hosted on GitHub at It is public so it can be cloned either through HTTPS or SSH without needing any particular credentials. It can also be forked freely. See the Programming Guide for details about pull requests and/or write access to the main repository.

Ideally, the main branch should have a usable snapshot. All other branches might contain code that might not compile or might not run or might not be tested. If you find a commit in the main branch that does not pass the tests, please report it in the issue tracker ASAP.

After cloning the repository

git clone

the script has to be called to bootstrap the working tree, since the configure script is not stored in the repository but created from (which is in the repository) by autogen.

Similarly, after updating the working tree with

git pull

it is recommended to re-run the script. It will do a make clean and re-compute the version string.

2.3.2 Source tarballs

When downloading a source tarball, there is no need to run since the configure script is already included in the tarball. This method cannot update the working tree. For each new FeenoX release, the whole tarball has to be downloaded again.

2.4 Configuration

To create a proper Makefile for the particular architecture, dependencies and compilation options, the script configure has to be executed. This procedure follows the GNU Coding Standards.


Without any particular options, configure will check if the mandatory GNU Scientific Library is available (both its headers and run-time library). If it is not, then the option --enable-download-gsl can be used. This option will try to use wget (which should be installed) to download a source tarball, uncompress is, configure and compile it. If these steps are successful, this GSL will be statically linked into the resulting FeenoX executable. If there is no internet connection, the configure script will say that the download failed. In that case, get the indicated tarball file manually , copy it into the current directory and re-run ./configure.

The script will also check for the availability of optional dependencies. At the end of the execution, a summary of what was found (or not) is printed in the standard output:

$ ./configure
## ----------------------- ##
## Summary of dependencies ##
## ----------------------- ##
  GNU Scientific Library  from system
  SUNDIALS IDA            yes
  PETSc                   yes /usr/lib/petsc 
  SLEPc                   no

If for some reason one of the optional dependencies is available but FeenoX should not use it, then pass --without-sundials, --without-petsc and/or --without-slepc as arguments. For example

$ ./configure --without-sundials --without-petsc
## ----------------------- ##
## Summary of dependencies ##
## ----------------------- ##
  GNU Scientific Library  from system
  SUNDIALS                no
  PETSc                   no
  SLEPc                   no

If configure complains about contradicting values from the cached ones, run again before configure or uncompress the source tarball in a fresh location.

To see all the available options run

./configure --help

2.5 Source code compilation

After the successful execution of configure, a Makefile is created. To compile FeenoX, just execute


Compilation should take a dozen of seconds. It can be even sped up by using the -j option

make -j8

The binary executable will be located in the src directory but a copy will be made in the base directory as well. Test it by running without any arguments

$ ./feenox
FeenoX v0.1.24-g6cfe063 
a free no-fee no-X uniX-like finite-element(ish) computational engineering tool

usage: ./feenox [options] inputfile [replacement arguments]

  -h, --help         display usage and commmand-line help and exit
  -v, --version      display brief version information and exit
  -V, --versions     display detailed version information
  -s, --sumarize     list all symbols in the input file and exit

Instructions will be read from standard input if “-” is passed as
inputfile, i.e.

    $ echo "PRINT 2+2" | feenox -

Report bugs at or to
Feenox home page:

The -v (or --version) option shows the version and a copyright notice:

$ ./feenox -v
FeenoX v0.1.24-g6cfe063
a free no-fee no-X uniX-like finite-element(ish) computational engineering tool

Copyright (C) 2009--2021 jeremy theler
GNU General Public License v3+, 
FeenoX is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

The -V (or --versions) option shows the dates of the last commits, the compiler options and the versions of the linked libraries:

$ ./feenox -V
FeenoX v0.1.24-g6cfe063
a free no-fee no-X uniX-like finite-element(ish) computational engineering tool

Last commit date   : Sun Aug 29 11:34:04 2021 -0300
Build date         : Sun Aug 29 11:44:50 2021 -0300
Build architecture : linux-gnu x86_64
Compiler           : gcc (Ubuntu 10.3.0-1ubuntu1) 10.3.0
Compiler flags     : -O3
Builder            : gtheler@chalmers
GSL version        : 2.6
SUNDIALS version   : 4.1.0
PETSc version      : Petsc Release Version 3.14.5, Mar 03, 2021 
PETSc arch         : 
PETSc options      : --build=x86_64-linux-gnu --prefix=/usr --includedir=${prefix}/include --mandir=${prefix}/share/man --infodir=${prefix}/share/info --sysconfdir=/etc --localstatedir=/var --with-option-checking=0 --with-silent-rules=0 --libdir=${prefix}/lib/x86_64-linux-gnu --runstatedir=/run --with-maintainer-mode=0 --with-dependency-tracking=0 --with-debugging=0 --shared-library-extension=_real --with-shared-libraries --with-pic=1 --with-cc=mpicc --with-cxx=mpicxx --with-fc=mpif90 --with-cxx-dialect=C++11 --with-opencl=1 --with-blas-lib=-lblas --with-lapack-lib=-llapack --with-scalapack=1 --with-scalapack-lib=-lscalapack-openmpi --with-ptscotch=1 --with-ptscotch-include=/usr/include/scotch --with-ptscotch-lib="-lptesmumps -lptscotch -lptscotcherr" --with-fftw=1 --with-fftw-include="[]" --with-fftw-lib="-lfftw3 -lfftw3_mpi" --with-superlu_dist=1 --with-superlu_dist-include=/usr/include/superlu-dist --with-superlu_dist-lib=-lsuperlu_dist --with-hdf5-include=/usr/include/hdf5/openmpi --with-hdf5-lib="-L/usr/lib/x86_64-linux-gnu/hdf5/openmpi -L/usr/lib/x86_64-linux-gnu/openmpi/lib -lhdf5 -lmpi" --CXX_LINKER_FLAGS=-Wl,--no-as-needed --with-hypre=1 --with-hypre-include=/usr/include/hypre --with-hypre-lib=-lHYPRE_core --with-mumps=1 --with-mumps-include="[]" --with-mumps-lib="-ldmumps -lzmumps -lsmumps -lcmumps -lmumps_common -lpord" --with-suitesparse=1 --with-suitesparse-include=/usr/include/suitesparse --with-suitesparse-lib="-lumfpack -lamd -lcholmod -lklu" --with-superlu=1 --with-superlu-include=/usr/include/superlu --with-superlu-lib=-lsuperlu --prefix=/usr/lib/petscdir/petsc3.14/x86_64-linux-gnu-real --PETSC_ARCH=x86_64-linux-gnu-real CFLAGS="-g -O2 -ffile-prefix-map=/build/petsc-pVufYp/petsc-3.14.5+dfsg1=. -flto=auto -ffat-lto-objects -fstack-protector-strong -Wformat -Werror=format-security -fPIC" CXXFLAGS="-g -O2 -ffile-prefix-map=/build/petsc-pVufYp/petsc-3.14.5+dfsg1=. -flto=auto -ffat-lto-objects -fstack-protector-strong -Wformat -Werror=format-security -fPIC" FCFLAGS="-g -O2 -ffile-prefix-map=/build/petsc-pVufYp/petsc-3.14.5+dfsg1=. -flto=auto -ffat-lto-objects -fstack-protector-strong -fPIC -ffree-line-length-0" FFLAGS="-g -O2 -ffile-prefix-map=/build/petsc-pVufYp/petsc-3.14.5+dfsg1=. -flto=auto -ffat-lto-objects -fstack-protector-strong -fPIC -ffree-line-length-0" CPPFLAGS="-Wdate-time -D_FORTIFY_SOURCE=2" LDFLAGS="-Wl,-Bsymbolic-functions -flto=auto -Wl,-z,relro -fPIC" MAKEFLAGS=w
SLEPc version      : SLEPc Release Version 3.14.2, Feb 01, 2021

2.6 Test suite

To be explained.

2.7 Installation

To be explained.

3 Advanced settings

3.1 Compiling with debug symbols

By default the C flags are -O3, without debugging. To add the -g flag, just use CFLAGS when configuring:

./configure CFLAGS="-g -O0"

3.2 Using a different compiler

Without PETSc, FeenoX uses the CC environment variable to set the compiler. So configure like

./configure CC=clang

When PETSc is detected FeenoX uses the mpicc executable, which is a wrapper to an actual C compiler with extra flags needed to find the headers and the MPI library. To change the wrapped compiler, you should set MPICH_CC or OMPI_CC, depending if you are using MPICH or OpenMPI. For example, to force MPICH to use clang do

./configure MPICH_CC=clang CC=clang

To know which is the default MPI implementation, just run configure without arguments and pay attention to the “Compiler” line in the “Summary of dependencies” section. For example, for OpenMPI a typical summary would be

## ----------------------- ##
## Summary of dependencies ##
## ----------------------- ##
  GNU Scientific Library  from system
  SUNDIALS                yes
  PETSc                   yes /usr/lib/petsc 
  SLEPc                   yes /usr/lib/slepc
  Compiler                gcc -I/usr/lib/x86_64-linux-gnu/openmpi/include/openmpi -I/usr/lib/x86_64-linux-gnu/openmpi/include -pthread -L/usr/lib/x86_64-linux-gnu/openmpi/lib -lmpi


## ----------------------- ##
## Summary of dependencies ##
## ----------------------- ##
  GNU Scientific Library  from system
  SUNDIALS                yes
  PETSc                   yes /home/gtheler/libs/petsc-3.15.0 arch-linux2-c-debug
  SLEPc                   yes /home/gtheler/libs/slepc-3.15.1
  Compiler                gcc -Wl,-z,relro -I/usr/include/x86_64-linux-gnu/mpich -L/usr/lib/x86_64-linux-gnu -lmpich

Other non-free implementations like Intel MPI might work but were not tested. However, it should be noted that the MPI implementation used to compile FeenoX has to match the one used to compile PETSc. Therefore, if you compiled PETSc on your own, it is up to you to ensure MPI compatibility. If you are using PETSc as provided by your distribution’s repositories, you will have to find out which one was used (it is usually OpenMPI) and use the same one when compiling FeenoX.

The FeenoX executable will show the configured compiler and flags when invoked with the --versions option:

$ feenox --versions
FeenoX v0.1.47-g868dbb7-dirty 
a free no-fee no-X uniX-like finite-element(ish) computational engineering tool

Last commit date   : Mon Sep 6 16:39:53 2021 -0300
Build date         : Tue Sep 07 14:29:42 2021 -0300
Build architecture : linux-gnu x86_64
Compiler           : gcc (Debian 10.2.1-6) 10.2.1 20210110
Compiler flags     : -O3
Builder            : gtheler@tom
GSL version        : 2.6
SUNDIALS version   : 5.7.0
PETSc version      : Petsc Release Version 3.15.0, Mar 30, 2021 
PETSc arch         : arch-linux2-c-debug
PETSc options      : --download-eigen --download-hdf5 --download-hypre --download-metis --download-mumps --download-parmetis --download-pragmatic --download-scalapack --with-x=0
SLEPc version      : SLEPc Release Version 3.15.1, May 28, 2021

Note that the reported values are the ones used in configure and not in make. Thus, the recommended way to set flags is in configure and not in make.

3.3 Compiling PETSc

To be explained.