Learning How to Use ROOT

ROOT is a general purpose graphing program that takes root files in and outputs root files or plots (eps, gif, png, etc). It is based in C++, although there is also a python version. The SingleTopRootAnalysis package used at MSU is based in C++, so if you are not already familiar with this programming language, it would be best to learn how to use ROOT with this language first. That package takes in D3PD ROOT files, applies selection cuts, and then outputs a root file of histograms before and after cuts (in its most simple application). For more information on the analysis package, see HowToUseTheAnalysisFramework. There are many resources online that will help you learn to use ROOT, which have been collected here:

• https://hep.pa.msu.edu/twiki/bin/view/Computing/MsuROOT

Another good resource is the ROOT manual itself, which you can find here:

• http://root.cern.ch/drupal/content/users-guide

Additional information may be found through the documentation link on this page:

• http://root.cern.ch/drupal/

This is the official ROOT page. The FAQ and How To's are particularly useful when you get stuck. Also, if you want to know about specific class methods or an error message you run into, google it. ROOT is widely used and often the problem has been encountered by someone else. Classes like TH1 (histograms of type TH1F, TH1D, etc) are documented online, so googling TH1 will give you a page with information at the top, and list of methods in the middle with links to descriptions (often short) at the end of the page.

-- JennyHolzbauer - 28 Sep 2009