    /*****************************************************************************
     * Project: RooFit                                                           *
     * Package: RooFitCore                                                       *
     *    File: $Id: RooPullVar.cc,v 1.4 2005/06/20 15:44:56 wverkerke Exp $
     * 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)             *
     *****************************************************************************/

    // -- CLASS DESCRIPTION [REAL] --
    //
    // RooPullVar calculates the pull of measurement w.r.t to true value
    // using the measurement value and its error. 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"

    ClassImp(RooPullVar)
    ;

     RooPullVar::RooPullVar()
    {
    }

     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)
    {
    }

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

     RooPullVar::~RooPullVar()
    {
    }

     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 ;
      }
    }