rf206_treevistools.C: 'ADDITION AND CONVOLUTION' RooFit tutorial macro #206

//////////////////////////////////////////////////////////////////////////
//
// 'ADDITION AND CONVOLUTION' RooFit tutorial macro #206
// 
// Tools for visualization of RooAbsArg expression trees
//
//
//
// 07/2008 - Wouter Verkerke 
// 
/////////////////////////////////////////////////////////////////////////

#ifndef __CINT__
#include "RooGlobalFunc.h"
#endif
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooChebychev.h"
#include "RooAddPdf.h"
#include "RooExponential.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "RooPlot.h"
using namespace RooFit ;


void rf206_treevistools()
{
  // S e t u p   c o m p o s i t e    p d f
  // --------------------------------------

  // Declare observable x
  RooRealVar x("x","x",0,10) ;

  // Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and their paramaters
  RooRealVar mean("mean","mean of gaussians",5) ;
  RooRealVar sigma1("sigma1","width of gaussians",0.5) ;
  RooRealVar sigma2("sigma2","width of gaussians",1) ;
  RooGaussian sig1("sig1","Signal component 1",x,mean,sigma1) ;  
  RooGaussian sig2("sig2","Signal component 2",x,mean,sigma2) ;  

  // Sum the signal components into a composite signal p.d.f.
  RooRealVar sig1frac("sig1frac","fraction of component 1 in signal",0.8,0.,1.) ;
  RooAddPdf sig("sig","Signal",RooArgList(sig1,sig2),sig1frac) ;
  
  // Build Chebychev polynomial p.d.f.  
  RooRealVar a0("a0","a0",0.5,0.,1.) ;
  RooRealVar a1("a1","a1",-0.2,0.,1.) ;
  RooChebychev bkg1("bkg1","Background 1",x,RooArgSet(a0,a1)) ;

  // Build expontential pdf
  RooRealVar alpha("alpha","alpha",-1) ;
  RooExponential bkg2("bkg2","Background 2",x,alpha) ;

  // Sum the background components into a composite background p.d.f.
  RooRealVar bkg1frac("bkg1frac","fraction of component 1 in background",0.2,0.,1.) ;
  RooAddPdf bkg("bkg","Signal",RooArgList(bkg1,bkg2),bkg1frac) ;
  
  // Sum the composite signal and background 
  RooRealVar bkgfrac("bkgfrac","fraction of background",0.5,0.,1.) ;
  RooAddPdf  model("model","g1+g2+a",RooArgList(bkg,sig),bkgfrac) ;


  // P r i n t   c o m p o s i t e   t r e e   i n   A S C I I 
  // -----------------------------------------------------------

  // Print tree to stdout
  model.Print("t") ;

  // Print tree to file
  model.printCompactTree("","rf206_asciitree.txt") ;


  // D r a w   c o m p o s i t e   t r e e   g r a p h i c a l l y 
  // -------------------------------------------------------------

  // Print GraphViz DOT file with representation of tree
  model.graphVizTree("rf206_model.dot") ;

  // Make graphic output file with one of the GraphViz tools
  // (freely available from www.graphviz.org)
  //
  // 'Top-to-bottom graph'
  // unix> dot -Tgif -o rf207_model_dot.gif rf207_model.dot
  //
  // 'Spring-model graph'
  // unix> fdp -Tgif -o rf207_model_fdp.gif rf207_model.dot

}