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Install ROOT

Follow these steps

Download

• Preferred Installation Method : the ROOT framework installation from source
  • Go to ROOT web site
  • Download the latest production version (see also the release notes)
    • Can also use the Git repository
  • Copy it from the download folder to the where you will install it.
    • In Catalina on OSX of the Mac , we are using ~/sw/root as the ROOT installation folder
    • The source file archive should now be in the folder ~/sw/root
  • Use "tar -xvf <filename> " to unpack the source file tree into this folder.
    • It will now look like this if you do a directory listing. ~/sw/root/root-6.26.00 with of course the version number of the latest version
  • Going down to the section "Two build methods", use the "cmake" build process. Find the link to this in the "Installing ROOT From Source" instructions
  • You will need to follow the link to first install "cmake" and add the path to the "cmake" binary into your PATH variable.
    • edit /etc/bashrc with "vi" and add the lines
      • PATH=$PATH:<path to cmake binary>
      • export PATH
      • in Catalina, with the zsh shell, replace .bashrc with .zshrc
      • This new environment only comes into effect if you re-open an ew shell.
  • Now click on the link to for the "instructions" build root with cmake.
    • Go into your ~/sw/root directory
      • mkdir <root-6.04.00-builddir>
      • mkdir <root-6.04.00-installdir>
      • cd <root-6.04.00-builddir>
      • cmake <srcdir (full path to root-6.04.00)> -DCMAKE_INSTALL_PREFIX=<installdir (full path to root-6.04.00-installdir>
      • make [or, make -jn for n core machines]
      • make install
  • You should make sure the path to the "thisroot.sh" is correct in your /etc/bashrc" file.
    • Google the setting up of the environment in linux.
    • In Catalina of Mac OSX its zsh, not bash, and you use instead the environment file ~/.zshrc
• If you already had a ROOT installation, then comment out the ROOT environment in your bashrc and work from a new shell (terminal)
  • If the new root which is installed from source is working, then remove all old versions which did not work perfectly.
  • You can add a lot of other definitions ... for example, for myself, i have
    • -Dmathmore=ON -Dminuit2=ON -Dbuiltin_vdt=ON, but there may need to be others, like special path to your python installation et.
    • Recently there is an issue with XROOTD on Mac ....
    • Install Xrootd with brew install xrootd
    • use these additional flags -Dbuiltin_xrootd=OFF -DXROOTD_ROOT_DIR=/usr/local/Cellar/xrootd
• ALTERNATIVE to build ROOT from source and libEvent
  • Follow these steps:
    • Command Line Tools for Xcode
      • xcode-select --install
    • Build root using make
      • sudo -s
      • mkdir /sw
      • cd /sw
      • tar zxvf ~/Downloads/root_v6.04.02.source.tar.gz
      • cd root-6.04.02
      • ./configure
      • make
    • Make sure your /etc/bashrc sources the correct script to establish the ROOT environment
      • . <path to the root bin directory>/thisroot.sh
    • You need to do this too to use TTree::MakeClass
      • cd test
      • make libEvent.so
      • cp libEvent.so EventDict_rdict.pcm ../macros
    • Now test the installation
      • root
      • .L libEvent.so
• First the ROOT framework itself - install of binaries
  • Go to ROOT web site
  • Select the Download menu option
  • Select the link .... Pro, version 6.04/00 recommended (see also the release notes)
  • Go down to the link for OSX, 10.10 x86-64 with clang 6.1, version 6.04.00 tar.gz or dmg (133 MB).
  • Click on the "dmg" file and it will download.
  • Find the ROOT dmg file and install ROOT ... following obvious steps.
• Now the ROOT Userguide
  • This in under "Documentation"
  • Choose the one sided pdf option ... development trunk version 6 ... you will consult this often

Set your environment

• Get the instructions from the link in the line "After downloading and unpacking please read the included README/README file on how to set the necessary environment variables." which you see at the bottom of the page where all the versions for download are.
• You will need to make your /etc/bashrc file automatically run a script to set the Environment by inserting this string in the file. ". <pathname>/root<version>/bin/thisroot.sh"
• <pathname> is where the root installation went. Probably /Applications/.

Check ROOT works

• issue the command "root" in a shell.
• you must open the shell afresh to get the updated environment from the previous step

Make sure you have "libEvent.so" installed

• in a root session, run .L libEvent.so ... check it runs with no errors
• if necessary, install libEvent.so in the root installdir
  • go to the root sourcedir, go to the test subdir, ... say make Event , it will build libEvent.so
  • copy this to the macros subdir of the root installer
• Also copy in the EventDict_rdict.pcm

Learn ROOT

• Do Chapters 2-5 as a Tutorial
  • Fire up ROOT ....
  • Have the UserGuide open
  • Have your editor open
  • Some examples are one liners ... enter them directly into the ROOT window
  • Some examples you must save as a code fragment.
    • Use your editor to do this.
    • You can give the extension .cpp again
    • Once again ... a folder per example !
    • Run the code by typing .x <filename> in the ROOT session
    • The examples are also in the tutorial section
• You should for example, understand and play with the "FittingDemo.C" from the tutorial/fit folder, as in Chapter 5 of the User Guide
• If you want to be more expert .. then also learn
  • chapters 6, 7, 12