We explain the procedure for a Linux C-shell, considering EPOS version 4.0.0 (to have a concrete case). After downloading the code, a couple of environment variables have to be defined, before compiling the code using CMake.
First, check on "Version" which versions are available and download the appropriate one.
Define environment variables concerning the EPOS version number (EPOVSN), the place where the tar file has been placed (MYDIR), and based on that the name of the EPOS directory (EPO):
setenv EPOVSN 4.0.0
setenv MYDIR $PWD/
setenv EPO ${MYDIR}epos${EPOVSN}/
Then one defines the place where intermediate files and executables should be placed (LIBDIR), and the directories for input (OPT), histogram output (HTO) and other kinds of output like run information and checks (CHK), like
setenv LIBDIR ${EPO}bin
setenv OPT ./
setenv HTO ./
setenv CHK ./
There are two compilation modes, the DEMO mode which allows simple applications and does not depend on external libraries, and the BASIC mode which allows standard EPOS applications, requiring the installation of ROOT and FASTJET. The mode needs to be defined via the variable COP. We will discuss the two options below.
cd $MYDIR
tar xvfz epos${EPOVSN}.tgz
setenv COP DEMO
cd $EPO
rm -Rf $LIBDIR && cmake3 -B$LIBDIR && make -C$LIBDIR -j8
cd examples/
$EPO/scripts/epos expl1
This will run EPOS taking input from expl1.optns. Output will be in z-expl1.histo and z-expl1.check, as explained via comments in the optns file. In the same way, one may use expl2, expl3, or expl4.
The latter one represents proton-proton scattering using the PFE option (parameterized fluid expansion), which allows fast simulations including collective effects, via fluid expansion and hadronic cascade. Most results are very similar to the (much slower) full simulation, so it may be useful for tests.
Here one first needs to install ROOT and FASTJET and define the two environment variables ROOTSYS and FASTSYS pointing to the corresponding directories, and put $ROOTSYS/bin and $FASTSYS/bin into the path, with something like
set path= ( $ROOTSYS/bin $FASTSYS/bin $path )
and then
setenv COP BASIC
setenv LD_LIBRARY_PATH $ROOTSYS/lib:$ROOTSYS/lib/root:/usr/local/lib
cd $EPO
rm -Rf $LIBDIR && cmake3 -B$LIBDIR && make -C$LIBDIR -j8
cd examples/
$EPO/scripts/epos expl5
In the same way, one may use expl1, expl2, expl3, expl4, or expl6.
The $EPO/scripts/epos script uses a fixed seed for the random number initialization, so running the code several times will produce identical results. To change this, one may replace "seedj=111111111" and "seedi=222222222" in the script by
seedj=`date '+%N'`
seedi=`date '+%N'`
which allows making parallel runs to increase statistics.