====== Installation from source code ======
In case a package for your system is not available or the standard package installation does not work, Focus can be installed using the source code. The compilation of Focus has some additional dependencies compared with the precompiled binary packages. Focus depends on Qt5 and FFTW to compile and additionally requires cmake and GNU compilers like ''g+ +'' and ''gfortran''.

===== Getting the source code =====
The latest source for Focus is available at our [[https://github.com/C-CINA/focus/archive/master.zip|GITHUB]] repository. Source code for [[https://github.com/C-CINA/focus/releases|previous releases]] is also available. Once downloaded the software can be extracted using ''unzip''.

Alternatively the GIT repository can also be cloned (For this, installation of ''git'' is required):

''git clone https://github.com/LBEM-CH/focus.git''

 ===== Installing Dependencies =====
 The dependencies for Focus are open source and free. They can be installed using standard package managers on various platforms. We recommend the following package managers for following operations systems:
  * MacOS: ''brew'' (https://brew.sh)
  * Ubuntu: ''apt-get''
  * Fedora/CentOS/RedHat: ''yum''

==== cmake ==== 
As we use cmake as build system you should have installed it on your machine. We advise to install this and most of the other dependencies by means of your native package manager. 
On OSX, for example, you could use "brew install cmake".
Alternatively, you can get cmake under the following link: http://www.cmake.org.

**NOTE:** Qt versions >= 5.7 (see below) will require a CMake version >= 3.1.0.
==== gfortran (incl. bindings) ====
Some programs of the kernel are written in fortran. Thus compiling Focus requires a fortran compiler. Note that we only support the GNU fortran compiler ''gfortran''. Dependent on your package source you might have to install some platform dependent binding libraries between fortran and c++. But on Fedora you have to install these additional packages: ''gcc-gfortran'' and ''libgfortran''.
On OSX, you can install this via "brew install gcc".

Please make sure to use gfortran **version 5.x** or later.


==== g++ (incl. bindings) ====
The GUI is written in c++ with c++11 standards and thus requires a corresponding compiler. Again on some RedHat-like Linux distributions you need to install some bindings. On Fedora Focus relies on the ''gcc-c++'' package.

For **MacOS**, one would probably need to install packages like gcc using homebrew or macports. 
This could be done with "brew install gcc ; brew link gcc".
If done so, the following should be added to path:

''/usr/local/bin:/opt/bin:/opt/local/bin:/usr/bin/:/usr/sbin''

Make sure that the gcc/g++ from the clang is not used to build otherwise it will fail.  
On OSX, you might have to do "cd /usr/local/bin ; \ln -s g++-9 g++ ; \ln -s gcc-9 gcc" .
Or, depending on the g++ and gcc versions that you have installed, you might need to do "cd /usr/local/bin ; \ln -s g++-8 g++ ; \ln -s gcc-8 gcc".
==== libfftw3 ====
Focus requires fftw version 3.0.0 or later. The package is called ''libfftw3-dev'' on Ubuntu, but on Fedora you have to install ''fftw-devel'' and ''fftw-libs''. You can install this famous library via the package manager or directly from http://www.fftw.org. In such a case use the following commands to compile FFTW:

<nowiki>
./configure --enable-shared --enable-single --enable-threads --enable-sse --enable-sse2 --with-pic;
</nowiki>

<nowiki>
make;
</nowiki>

<nowiki>
sudo make install;
</nowiki>

<nowiki>
make clean;
</nowiki>

<nowiki>
./configure --enable-shared --enable-threads --enable-sse2 --with-pic;
</nowiki>

<nowiki>
make;
</nowiki>

<nowiki>
sudo make install
</nowiki>

==== Qt5 ====
Compilations of Qt5 is included in all the package managers we listed above. Qt5 can also be downloaded and installed from: http://www.qt.io/download-open-source/

You also need the "qtscript5-dev - Qt 5 script development files", which are not installed by default with Qt5. 
Installing the qtscript5-dev is also needed. 

On Linux, the command 

''sudo apt-get install qtscript5-dev
''

solves that problem.

Make sure that after the installation you add Qt5 bin directory to the environment variable $PATH, and that:

''qmake -query
''

gives you correct path to installed Qt libraries.

**NOTE:** Building with Qt versions >= 5.7 will require a CMake version >= 3.1.0.

**NOTE for Mac OSX Users:** Qt Version 5.9.4 worked fine, while Qt Version 5.10.1 caused the error:
"build/apps/src/data/moc_ParameterConfiguration.cpp:175:63: error: 'init_priority' attribute is not supported on this platform."


===== Compiling Focus =====
Once everything is set up, CMAKE will automatically find the required paths and compile. This all has been scripted and Focus can easily be compiled by running the ''build_all'' script, which take between
zero and two arguments. The list below shows you all the possibilities:
  * without arguments (''./build_all''): Focus will be built in build directory inside source code and installed into ~/focus.
  * with one argument (''./build_all <dir>''): You can specify your install and build location by passing an absolute path to the build script.
  * with two arguments (''./build_all <build_dir> <install_dir>''): The build script with two arguments performs an out-of-place installation of Focus. The first passed absolute path corresponds to the build directory while the second defines the install directory.

Focus is compiled in two stages. First we check the presence of all required dependencies and in the second stage we compile the entire source tree.

Upon building, Focus creates a directory "build", in which the configuration and built files are placed.  If compilation fails due to missing or wrong dependencies, and you add those dependencies later, then don't forget to remove the "build" directory before trying to "./build_all" again. Otherwise, the old configuration files in the "build" directory will still be present and steer the compilation into the wrong direction.

=== See also: ===
[[1_0:external-tools|Setting up external software tools]]

[[1_0:locating-installation|Default installation directories]]