RooPullVar.cxx

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/*****************************************************************************
 * Project: RooFit                                                           *
 * Package: RooFitCore                                                       *
 * @(#)root/roofitcore:$Id$
 * Authors:                                                                  *
 *   WV, Wouter Verkerke, UC Santa Barbara, verkerke@slac.stanford.edu       *
 *   DK, David Kirkby,    UC Irvine,         dkirkby@uci.edu                 *
 *                                                                           *
 * Copyright (c) 2000-2005, Regents of the University of California          *
 *                          and Stanford University. All rights reserved.    *
 *                                                                           *
 * Redistribution and use in source and binary forms,                        *
 * with or without modification, are permitted according to the terms        *
 * listed in LICENSE (http://roofit.sourceforge.net/license.txt)             *
 *****************************************************************************/

/**
\file RooPullVar.cxx
\class RooPullVar
\ingroup Roofitcore

Class RooPullVar represents the pull of measurement w.r.t to true value
using the measurement value and its error. Both the true value and
the measured value (with error) are taken from two user supplied
RooRealVars. If an asymmetric error is defined on a given measurement the proper 
side of that asymmetric error will be used
**/

#include "RooFit.h"

#include "Riostream.h"
#include "Riostream.h"
#include <math.h>

#include "RooPullVar.h"
#include "RooAbsReal.h"
#include "RooRealVar.h"

using namespace std;

ClassImp(RooPullVar)
;


////////////////////////////////////////////////////////////////////////////////
/// Default constructor

RooPullVar::RooPullVar()
{
}



////////////////////////////////////////////////////////////////////////////////
/// Construct RooAbsReal representing the pull of a RooRealVar 'meas' providing the
/// measured value and its error and a RooAbsReal 'truth' providing the true value

RooPullVar::RooPullVar(const char* name, const char* title, RooRealVar& meas, RooAbsReal& truth) :
  RooAbsReal(name, title),
  _meas("meas","Measurement",this,meas),
  _true("true","Truth",this,truth)
{
}





////////////////////////////////////////////////////////////////////////////////
/// Copy constructor

RooPullVar::RooPullVar(const RooPullVar& other, const char* name) :
  RooAbsReal(other, name), 
  _meas("meas",this,other._meas),
  _true("true",this,other._true)
{
}



////////////////////////////////////////////////////////////////////////////////
/// Destructor

RooPullVar::~RooPullVar() 
{
}



////////////////////////////////////////////////////////////////////////////////
/// Calculate pull. Use asymmetric error if defined in measurement,
/// otherwise use symmetric error. If measurement has no error
/// return zero.

Double_t RooPullVar::evaluate() const 
{
  const RooRealVar& meas = static_cast<const RooRealVar&>(_meas.arg()) ;  
  if (meas.hasAsymError()) {
    Double_t delta = _meas-_true ;
    if (delta<0) {
      return delta/meas.getAsymErrorHi() ;
    } else {
      return -delta/meas.getAsymErrorLo() ;
    }
  } else if (meas.hasError()) {
    return (_meas-_true)/meas.getError() ;    
  } else {
    return 0 ;
  }
}