This chapter is designed for impatient people who wants to test Feel++ as soon as possible.
Before installing Feel++, you need to get this required packages :
Feel++ is distributed as a tarball once in a while. The tarballs are available at
Download the latest tarball. Then follow the steps and replace x, y, z
with the corresponding numbers
tar xzf feel-x.y.z.tar.gz cd feel-x.y.z
We define then the current directory as the source one, ie:
export FeelppSrcDir=`pwd`
Please, notice that 4 Gbytes of RAM is a minimum to make Feel++ compiling (with GCC
), with clang, the memory footprint is much lower.
In order to compile Feel++ and a test application, we create a new directory:
mkdir build cd build export buildDir=`pwd`
and then, we are able to compile our first application:
cd $buildDir cmake $FeelppSrcDir make -j4
This procedure will build the entire librarie (with DebWithRelInfo option) and a dummy program to presents the Feel++'s abilities.
There is a procedure to install as a system librarie Feel++.
make install
See chapter 2 for more details.
As an introduction to the aim and the way to do with Feel++, we provide a sort of Hello World
program to evaluate the library.
We want to solve the simplest problem:
where .
That problem written in variational form is:
looks for
with:
The aim of Feel++ is to provide the simplest way to write the $a$ and $f$ forms.
From a discrete point of view, we introduce such that:
where is the set of element
forming the mesh of
.
We now look for such that:
This section is here to declare that we want to use the namespace Feel++, to passe the command line options to the created environnement and add some informations (basics Feel++ options, application name).
We have to define the mesh, the approximation space and our test and trial functions.
We create now our bilinear and linear forms, we add the homogeneous Dirichlet conditions and solve the discretized (linear) system.
Feel++ provides the possibility to save the results:
To test that part of code, please go to:
cd $FeelppSrcDir/quickstart
and execute the code, by:
./feelpp_qs_laplacian
This will produce several files:
qs_laplacian-1_0.case qs_laplacian-1.sos qs_laplacian.timeset qs_laplacian.u-1_0.001 qs_laplacian-1_0.geo001 qs_laplacian.pid-1_0.001 square.geo square.msh
You can vizualise the results using any Ensight file reader, such as Paraview, opening =qs_laplacian-1.sos=.
paraview qs_laplacian-1.sos
You may have a look to the differents option provided by
./feelpp_qs_laplacian --help