Notes on using the ROOT libraries in standalone C++ programs

In the coming problem sheets you will need to write C++ programs that
use classes from the ROOT library, and you will also produce plots
with the program root.  To do this, you need to execute a setup script
for the program, which defines the environment variable ROOTSYS.

For most accounts, this should already be done for you automatically.
To check, type

  echo $ROOTSYS

It should type back something like

  /usr/local/root/v5.30.01/slc5.gcc4.1-x86_64/root

Then everything is OK.  If ROOTSYS is not defined, you can add
the line 

  source /usr/local/root/v5.30.01/slc5.gcc4.1-x86_64/setup.sh

to the file .bash_profile which you have in your home directory (see
this by typing ls -la).  Or if you don't have a .bash_profile file, on
linappserv0 you can do

  cd
  cp ~cowan/WWW/stat/comp/.bash_profile ./

Then once you have the file, type

  source .bash_profile

You only have to do this once, as it will now automatically be done
every time you log in.  This defines some things needed to work with
the ROOT libraries.

For people not at RHUL, the location of the setup.sh file should be
similar.  Note that if you're using the csh or tcsh shell (instead of
bash), you should use the file setup.csh (not setup.sh).

Once you have done the above, download the files from

http://www.pp.rhul.ac.uk/~cowan/stat/root/mc/

into a convenient subdirectory and build the program simpleMC by
typing gmake.  Similar to what we did with .bash_profile, an easy way
to copy the files is first to cd to your local work directory on
linappserv0, then type

cp ~cowan/WWW/stat/root/mc/* ./

More info as well as instructions on how to produce plots with the
program root can be found in the file readme.txt in the web area
above.  More general information about root can be found at
root.cern.ch.


Glen Cowan
10 November, 2011