class HepTemplateFitter: public TTask

    This Tool provides the functionality to define templates whose
    weighted sum is then fitted to a reference. The fractions of
    the individual samples as well es the fitted templates themselves
    are returned to the user.

    In order to use the tool you have to write a task file in the
    fashion described below. If you have experience with the
    HepDataMCPlotter you should not have any problems.

    The example is taken from a flavor ratio analysis in the
    semileptonic ttbar channel



    {
    // Define a new task
    TTask *ttbar = new TTask("ttbar", "TTbar Analysis");

    // Initialize HepTemplatefitter with name and title. The Name
    // sets the name of the .root file that will be written.
    HepTemplateFitter *pl_ttbar = new HepTemplateFitter("Template Fitter", "Template plots");

    // AddMCSample adds samples to the list from which the templates will be
    // generated.
    // Parameter 1 is the pathname of the sample
    // Parameter 2 is the title of the MCSample
    // Parameter 3 is the cross section of the sample since it is possible
    // to generate templates from multiple files.
    pl_ttbar->AddMCSample("templatetest.root", "MC t#bar{t} Np0 qq", 1.0);

    // AddDatasample adds samples to the list from which the reference histogram
    // will be generated. Since one may want to do template fits in MC also
    // it is implemented similiar to AddMCSample
    pl_ttbar->AddDataSample("FRTest.root", "MC t#bar{t} Np0 qq", 1.0);

    // This generates the templates out of the MCSample files.
    // Parameter 1 is the name of the histogram from which the template is derived
    // Parameter 2 is the title of the parameter (for legends)
    // Parameter 3 is the color of the template
    pl_ttbar->GenerateTemplate("h_Masstemplate_uds", "light", kOrange);
    pl_ttbar->GenerateTemplate("h_Masstemplate_c", "charm", kRed);
    pl_ttbar->GenerateTemplate("h_Masstemplate_b", "bottom", kBlue);
    pl_ttbar->GenerateTemplate("h_Masstemplate_x", "unknown", kGreen);

    // Sets the reference. The parameter is the name of the histogram
    // from which the reference is generated.
    pl_ttbar->GenerateReference("h_jets_mass_all");

    // Add the Fitter to the task
    ttbar->Add(pl_ttbar);

    // Open browser
    gROOT->GetListOfTasks()->Add(ttbar);
    gROOT->GetListOfBrowsables()->Add(ttbar);
    new TBrowser;
    }



    Now execute the task and you will get the results of the fit.


 Author: Felix Thomas <mailto: Felix.Thomas@mailbox-tu-dresden.de>
 Update: $$
 Copyright: 2010 (C) Felix Thomas