/*****************************************************************************
 * Project: RooFit                                                           *
 * Package: RooFitCore                                                       *
 * @(#)root/roofitcore:$Id: RooAbsRealLValue.cxx 28259 2009-04-16 16:21:16Z wouter $
 * 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)             *
 *****************************************************************************/

//////////////////////////////////////////////////////////////////////////////
// 
// BEGIN_HTML
// RooAbsRealLValue is the common abstract base class for objects that represent a
// real value that may appear on the left hand side of an equation ('lvalue')
// Each implementation must provide a setVal() member to allow direct modification 
// of the value. RooAbsRealLValue may be derived, but its functional relation
// to other RooAbsArg must be invertible
//
// This class has methods that export the defined range of the lvalue,
// but doesn't hold its values because these limits may be derived
// from limits of client object.  The range serve as integration
// range when interpreted as a observable and a boundaries when
// interpreted as a parameter.
// END_HTML
//
//

#include "RooFit.h"

#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "Riostream.h"
#include "TObjString.h"
#include "TTree.h"
#include "TH1.h"
#include "TH2.h"
#include "TH3.h"
#include "RooAbsRealLValue.h"
#include "RooStreamParser.h"
#include "RooRandom.h"
#include "RooPlot.h"
#include "RooArgList.h"
#include "RooAbsBinning.h"
#include "RooBinning.h"
#include "RooUniformBinning.h"
#include "RooCmdConfig.h"
#include "RooTreeData.h"
#include "RooRealVar.h"
#include "RooMsgService.h"



ClassImp(RooAbsRealLValue)

//_____________________________________________________________________________
RooAbsRealLValue::RooAbsRealLValue(const char *name, const char *title, const char *unit) :
  RooAbsReal(name, title, 0, 0, unit)
{
  // Constructor
}  



//_____________________________________________________________________________
RooAbsRealLValue::RooAbsRealLValue(const RooAbsRealLValue& other, const char* name) :
  RooAbsReal(other,name), RooAbsLValue(other)
{
  // Copy constructor
}


//_____________________________________________________________________________
RooAbsRealLValue::~RooAbsRealLValue() 
{
  // Destructor
}



//_____________________________________________________________________________
Bool_t RooAbsRealLValue::inRange(Double_t value, const char* rangeName, Double_t* clippedValPtr) const
{
  // Return kTRUE if the input value is within our fit range. Otherwise, return
  // kFALSE and write a clipped value into clippedValPtr if it is non-zero.

  // Double_t range = getMax() - getMin() ; // ok for +/-INIFINITY
  Double_t clippedValue(value);
  Bool_t isInRange(kTRUE) ;

  // test this value against our upper fit limit
  if(hasMax() && value > (getMax(rangeName)+1e-6)) {
    if (clippedValPtr) {
//       coutW(InputArguments) << "RooAbsRealLValue::inFitRange(" << GetName() << "): value " << value
// 			    << " rounded down to max limit " << getMax(rangeName) << endl ;
    }
    clippedValue = getMax(rangeName);
    isInRange = kFALSE ;
  }
  // test this value against our lower fit limit
  if(hasMin() && value < getMin(rangeName)-1e-6) {
    if (clippedValPtr) {
//       coutW(InputArguments) << "RooAbsRealLValue::inFitRange(" << GetName() << "): value " << value
// 			    << " rounded up to min limit " << getMin(rangeName) << endl;
    }
    clippedValue = getMin(rangeName);
    isInRange = kFALSE ;
  } 

  if (clippedValPtr) *clippedValPtr=clippedValue ;
  return isInRange ;
}



//_____________________________________________________________________________
Bool_t RooAbsRealLValue::isValidReal(Double_t value, Bool_t verbose) const 
{
  // Check if given value is valid

  if (!inRange(value,0)) {
    if (verbose)
      coutI(InputArguments) << "RooRealVar::isValid(" << GetName() << "): value " << value
			    << " out of range (" << getMin() << " - " << getMax() << ")" << endl ;
    return kFALSE ;
  }
  return kTRUE ;
}                                                                                                                         



//_____________________________________________________________________________
Bool_t RooAbsRealLValue::readFromStream(istream& /*is*/, Bool_t /*compact*/, Bool_t /*verbose*/) 
{
  // Read object contents from given stream

  return kTRUE ;
}



//_____________________________________________________________________________
void RooAbsRealLValue::writeToStream(ostream& /*os*/, Bool_t /*compact*/) const
{
  // Write object contents to given stream
}



//_____________________________________________________________________________
RooAbsArg& RooAbsRealLValue::operator=(Double_t newValue) 
{
  // Assignment operator from a Double_t

  Double_t clipValue ;
  // Clip 
  inRange(newValue,0,&clipValue) ;
  setVal(clipValue) ;

  return *this ;
}


//_____________________________________________________________________________
RooAbsArg& RooAbsRealLValue::operator=(const RooAbsReal& arg) 
{
  // Assignment operator from other RooAbsReal
  return operator=(arg.getVal()) ;
}



//_____________________________________________________________________________
RooPlot* RooAbsRealLValue::frame(const RooCmdArg& arg1, const RooCmdArg& arg2, const RooCmdArg& arg3, const RooCmdArg& arg4,
				 const RooCmdArg& arg5, const RooCmdArg& arg6, const RooCmdArg& arg7, const RooCmdArg& arg8) const 

  // Create a new RooPlot on the heap with a drawing frame initialized for this
  // object, but no plot contents. Use x.frame() as the first argument to a
  // y.plotOn(...) method, for example. The caller is responsible for deleting
  // the returned object.
  //
  // This function takes the following named arguments
  //
  // Range(double lo, double hi)          -- Make plot frame for the specified range
  // Range(const char* name)              -- Make plot frame for range with the specified name
  // Bins(Int_t nbins)                    -- Set default binning for datasets to specified number of bins
  // AutoRange(const RooAbsData& data,    -- Specifies range so that all points in given data set fit 
  //                    double margin)       inside the range with given margin.
  // AutoSymRange(const RooAbsData& data, -- Specifies range so that all points in given data set fit 
  //                    double margin)       inside the range and center of range coincides with mean
  //                                         of distribution in given dataset. 
  // Name(const char* name)               -- Give specified name to RooPlot object 
  // Title(const char* title)             -- Give specified title to RooPlot object
  //  
{
  RooLinkedList cmdList ;
  cmdList.Add(const_cast<RooCmdArg*>(&arg1)) ; cmdList.Add(const_cast<RooCmdArg*>(&arg2)) ;
  cmdList.Add(const_cast<RooCmdArg*>(&arg3)) ; cmdList.Add(const_cast<RooCmdArg*>(&arg4)) ;
  cmdList.Add(const_cast<RooCmdArg*>(&arg5)) ; cmdList.Add(const_cast<RooCmdArg*>(&arg6)) ;
  cmdList.Add(const_cast<RooCmdArg*>(&arg7)) ; cmdList.Add(const_cast<RooCmdArg*>(&arg8)) ;

  return frame(cmdList) ;
}



//_____________________________________________________________________________
RooPlot* RooAbsRealLValue::frame(const RooLinkedList& cmdList) const 
{
  // Back-end function for named argument frame() method

  // Define configuration for this method
  RooCmdConfig pc(Form("RooAbsRealLValue::frame(%s)",GetName())) ;
  pc.defineDouble("min","Range",0,getMin()) ;
  pc.defineDouble("max","Range",1,getMax()) ;
  pc.defineInt("nbins","Bins",0,getBins()) ;
  pc.defineString("rangeName","RangeWithName",0,"") ;
  pc.defineString("name","Name",0,"") ;
  pc.defineString("title","Title",0,"") ;
  pc.defineMutex("Range","RangeWithName","AutoRange") ;
  pc.defineObject("rangeData","AutoRange",0,0) ;
  pc.defineDouble("rangeMargin","AutoRange",0,0.1) ;
  pc.defineInt("rangeSym","AutoRange",0,0) ;

  // Process & check varargs 
  pc.process(cmdList) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }

  // Extract values from named arguments
  Double_t xmin,xmax ;
  if (pc.hasProcessed("Range")) {
    xmin = pc.getDouble("min") ;
    xmax = pc.getDouble("max") ;
    if (xmin==xmax) {
      xmin = getMin() ;
      xmax = getMax() ;
    }
  } else if (pc.hasProcessed("RangeWithName")) {
    const char* rangeName=pc.getString("rangeName",0,kTRUE) ;
    xmin = getMin(rangeName) ;
    xmax = getMax(rangeName) ;
  } else if (pc.hasProcessed("AutoRange")) {
    RooTreeData* rangeData = static_cast<RooTreeData*>(pc.getObject("rangeData")) ;
    rangeData->getRange((RooRealVar&)*this,xmin,xmax) ;
    if (pc.getInt("rangeSym")==0) {
      // Regular mode: range is from xmin to xmax with given extra margin
      Double_t margin = pc.getDouble("rangeMargin")*(xmax-xmin) ;    
      xmin -= margin ;
      xmax += margin ; 
      if (xmin<getMin()) xmin = getMin() ;
      if (xmin>getMax()) xmax = getMax() ;
    } else {
      // Symmetric mode: range is centered at mean of distribution with enough width to include
      // both lowest and highest point with margin
      Double_t mean = rangeData->moment((RooRealVar&)*this,1) ;
      Double_t delta = ((xmax-mean)>(mean-xmin)?(xmax-mean):(mean-xmin))*(1+pc.getDouble("rangeMargin")) ;
      xmin = mean-delta ;
      xmax = mean+delta ;
      if (xmin<getMin()) xmin = getMin() ;
      if (xmin>getMax()) xmax = getMax() ;
    }
  } else {
    xmin = getMin() ;
    xmax = getMax() ;
  }

  Int_t nbins = pc.getInt("nbins") ;
  const char* name = pc.getString("name",0,kTRUE) ;
  const char* title = pc.getString("title",0,kTRUE) ;

  RooPlot* theFrame = new RooPlot(*this,xmin,xmax,nbins) ;

  if (name) {
    theFrame->SetName(name) ;
  }
  if (title) {
    theFrame->SetTitle(title) ;
  }

  return theFrame ;
}



//_____________________________________________________________________________
RooPlot *RooAbsRealLValue::frame(Double_t xlo, Double_t xhi, Int_t nbins) const 
{
  // Create a new RooPlot on the heap with a drawing frame initialized for this
  // object, but no plot contents. Use x.frame() as the first argument to a
  // y.plotOn(...) method, for example. The caller is responsible for deleting
  // the returned object.

  return new RooPlot(*this,xlo,xhi,nbins);
}



//_____________________________________________________________________________
RooPlot *RooAbsRealLValue::frame(Double_t xlo, Double_t xhi) const 
{
  // Create a new RooPlot on the heap with a drawing frame initialized for this
  // object, but no plot contents. Use x.frame() as the first argument to a
  // y.plotOn(...) method, for example. The caller is responsible for deleting
  // the returned object.

  return new RooPlot(*this,xlo,xhi,getBins());
}



//_____________________________________________________________________________
RooPlot *RooAbsRealLValue::frame(Int_t nbins) const 
{
  // Create a new RooPlot on the heap with a drawing frame initialized for this
  // object, but no plot contents. Use x.frame() as the first argument to a
  // y.plotOn(...) method, for example. The caller is responsible for deleting
  // the returned object.
  //
  // The current fit range may not be open ended or empty.

  // Plot range of variable may not be infinite or empty
  if (getMin()==getMax()) {
    coutE(InputArguments) << "RooAbsRealLValue::frame(" << GetName() << ") ERROR: empty fit range, must specify plot range" << endl ;
    return 0 ;
  }
  if (RooNumber::isInfinite(getMin())||RooNumber::isInfinite(getMax())) {
    coutE(InputArguments) << "RooAbsRealLValue::frame(" << GetName() << ") ERROR: open ended fit range, must specify plot range" << endl ;
    return 0 ;
  }

  return new RooPlot(*this,getMin(),getMax(),nbins);
}



//_____________________________________________________________________________
RooPlot *RooAbsRealLValue::frame() const 
{
  // Create a new RooPlot on the heap with a drawing frame initialized for this
  // object, but no plot contents. Use x.frame() as the first argument to a
  // y.plotOn(...) method, for example. The caller is responsible for deleting
  // the returned object.
  //
  // The current fit range may not be open ended or empty.

  // Plot range of variable may not be infinite or empty
  if (getMin()==getMax()) {
    coutE(InputArguments) << "RooAbsRealLValue::frame(" << GetName() << ") ERROR: empty fit range, must specify plot range" << endl ;
    return 0 ;
  }
  if (RooNumber::isInfinite(getMin())||RooNumber::isInfinite(getMax())) {
    coutE(InputArguments) << "RooAbsRealLValue::frame(" << GetName() << ") ERROR: open ended fit range, must specify plot range" << endl ;
    return 0 ;
  }

  return new RooPlot(*this,getMin(),getMax(),getBins());
}



//_____________________________________________________________________________
void RooAbsRealLValue::copyCache(const RooAbsArg* source, Bool_t /*valueOnly*/) 
{
  // Copy cache of another RooAbsArg to our cache

  RooAbsReal::copyCache(source) ;
  setVal(_value) ; // force back-propagation
}


//_____________________________________________________________________________
void RooAbsRealLValue::printMultiline(ostream& os, Int_t contents, Bool_t verbose, TString indent) const
{  
  // Structure printing

  RooAbsReal::printMultiline(os,contents,verbose,indent);
  os << indent << "--- RooAbsRealLValue ---" << endl;
  TString unit(_unit);
  if(!unit.IsNull()) unit.Prepend(' ');
  os << indent << "  Fit range is [ ";
  if(hasMin()) {
    os << getMin() << unit << " , ";
  }
  else {
    os << "-INF , ";
  }
  if(hasMax()) {
    os << getMax() << unit << " ]" << endl;
  }
  else {
    os << "+INF ]" << endl;
  }
}



//_____________________________________________________________________________
void RooAbsRealLValue::randomize(const char* rangeName) 
{
  // Set a new value sampled from a uniform distribution over the fit range.
  // Prints a warning and does nothing if the fit range is not finite.
  
  if(hasMin(rangeName) && hasMax(rangeName)) {
    Double_t range= getMax(rangeName)-getMin(rangeName);
    setVal(getMin(rangeName) + RooRandom::uniform()*range);
  }
  else {
    coutE(Generation) << fName << "::" << ClassName() << ":randomize: fails with unbounded fit range" << endl;
  }
}



//_____________________________________________________________________________
void RooAbsRealLValue::setBin(Int_t ibin, const char* rangeName) 
{
  // Set value to center of bin 'ibin' of binning 'rangeName' (or of 
  // default binning if no range is specified)

  // Check range of plot bin index
  if (ibin<0 || ibin>=numBins(rangeName)) {
    coutE(InputArguments) << "RooAbsRealLValue::setBin(" << GetName() << ") ERROR: bin index " << ibin
			  << " is out of range (0," << getBins(rangeName)-1 << ")" << endl ;
    return ;
  }
 
  // Set value to center of requested bin
  setVal(getBinning(rangeName).binCenter(ibin)) ;
}





//_____________________________________________________________________________
void RooAbsRealLValue::setBin(Int_t ibin, const RooAbsBinning& binning) 
{
  // Set value to center of bin 'ibin' of binning 'binning' 

  // Set value to center of requested bin
  setVal(binning.binCenter(ibin)) ;
}





//_____________________________________________________________________________
void RooAbsRealLValue::randomize(const RooAbsBinning& binning) 
{
  // Set a new value sampled from a uniform distribution over the fit range.
  // Prints a warning and does nothing if the fit range is not finite.
  
  Double_t range= binning.highBound() - binning.lowBound() ;
  setVal(binning.lowBound() + RooRandom::uniform()*range);
}





//_____________________________________________________________________________
void RooAbsRealLValue::setBinFast(Int_t ibin, const RooAbsBinning& binning) 
{
  // Set value to center of bin 'ibin' of binning 'rangeName' (or of 
  // default binning if no range is specified)

  // Set value to center of requested bin
  setValFast(binning.binCenter(ibin)) ;
}



//_____________________________________________________________________________
Bool_t RooAbsRealLValue::fitRangeOKForPlotting() const 
{
  // Check if fit range is usable as plot range, i.e. it is neither
  // open ended, nor empty
  return (hasMin() && hasMax() && (getMin()!=getMax())) ;
}



//_____________________________________________________________________________
Bool_t RooAbsRealLValue::inRange(const char* name) const 
{
  // Check if current value is inside range with given name

  return (getVal() >= getMin(name) && getVal() <= getMax(name)) ;
}



//_____________________________________________________________________________
TH1* RooAbsRealLValue::createHistogram(const char *name, const RooCmdArg& arg1, const RooCmdArg& arg2, 
					const RooCmdArg& arg3, const RooCmdArg& arg4, const RooCmdArg& arg5, 
					const RooCmdArg& arg6, const RooCmdArg& arg7, const RooCmdArg& arg8) const 

  // Create an empty ROOT histogram TH1,TH2 or TH3 suitabe to store information represent by the RooAbsRealLValue
  //
  // This function accepts the following arguments
  //
  // name -- Name of the ROOT histogram
  //
  // Binning(const char* name)                    -- Apply binning with given name to x axis of histogram
  // Binning(RooAbsBinning& binning)              -- Apply specified binning to x axis of histogram
  // Binning(int_t nbins)                         -- Apply specified binning to x axis of histogram
  // Binning(int_t nbins, double lo, double hi)   -- Apply specified binning to x axis of histogram
  // ConditionalObservables(const RooArgSet& set) -- Do not normalized PDF over following observables when projecting PDF into histogram
  //
  // YVar(const RooAbsRealLValue& var,...)    -- Observable to be mapped on y axis of ROOT histogram
  // ZVar(const RooAbsRealLValue& var,...)    -- Observable to be mapped on z axis of ROOT histogram
  //
  // The YVar() and ZVar() arguments can be supplied with optional Binning() arguments to control the binning of the Y and Z axes, e.g.
  // createHistogram("histo",x,Binning(-1,1,20), YVar(y,Binning(-1,1,30)), ZVar(z,Binning("zbinning")))
  //
  // The caller takes ownership of the returned histogram
{
  RooLinkedList l ;
  l.Add((TObject*)&arg1) ;  l.Add((TObject*)&arg2) ;  
  l.Add((TObject*)&arg3) ;  l.Add((TObject*)&arg4) ;
  l.Add((TObject*)&arg5) ;  l.Add((TObject*)&arg6) ;  
  l.Add((TObject*)&arg7) ;  l.Add((TObject*)&arg8) ;

  return createHistogram(name,l) ;
}



//_____________________________________________________________________________
TH1* RooAbsRealLValue::createHistogram(const char *name, const RooLinkedList& cmdList) const 
{  
  // Create empty 1,2 or 3D histogram
  // Arguments recognized
  //
  // YVar() -- RooRealVar defining Y dimension with optional range/binning
  // ZVar() -- RooRealVar defining Z dimension with optional range/binning
  // AxisLabel() -- Vertical axis label
  // Binning() -- Range/Binning specification of X axis

  // Define configuration for this method
  RooCmdConfig pc(Form("RooAbsRealLValue::createHistogram(%s)",GetName())) ;

  pc.defineObject("xbinning","Binning",0,0) ;
  pc.defineString("xbinningName","BinningName",0,"") ;
  pc.defineInt("nxbins","BinningSpec",0) ;
  pc.defineDouble("xlo","BinningSpec",0,0) ;
  pc.defineDouble("xhi","BinningSpec",1,0) ;

  pc.defineObject("yvar","YVar",0,0) ;
  pc.defineObject("ybinning","YVar::Binning",0,0) ;
  pc.defineString("ybinningName","YVar::BinningName",0,"") ;
  pc.defineInt("nybins","YVar::BinningSpec",0) ;
  pc.defineDouble("ylo","YVar::BinningSpec",0,0) ;
  pc.defineDouble("yhi","YVar::BinningSpec",1,0) ;

  pc.defineObject("zvar","ZVar",0,0) ;
  pc.defineObject("zbinning","ZVar::Binning",0,0) ;
  pc.defineString("zbinningName","ZVar::BinningName",0,"") ;
  pc.defineInt("nzbins","ZVar::BinningSpec",0) ;
  pc.defineDouble("zlo","ZVar::BinningSpec",0,0) ;
  pc.defineDouble("zhi","ZVar::BinningSpec",1,0) ;

  pc.defineString("axisLabel","AxisLabel",0,"Events") ;

  pc.defineDependency("ZVar","YVar") ;

  // Process & check varargs 
  pc.process(cmdList) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }

  // Initialize arrays for call to implementation version of createHistogram
  const char* axisLabel = pc.getString("axisLabel") ;
  const RooAbsBinning* binning[3] ;
  Bool_t ownBinning[3]  = { kFALSE, kFALSE, kFALSE } ;
  RooArgList vars ;

  // Prepare X dimension
  vars.add(*this) ;
  if (pc.hasProcessed("Binning")) {
    binning[0] = static_cast<RooAbsBinning*>(pc.getObject("xbinning")) ;
  } else if (pc.hasProcessed("BinningName")) {
    binning[0] = &getBinning(pc.getString("xbinningName",0,kTRUE)) ;
  } else if (pc.hasProcessed("BinningSpec")) {
    Double_t xlo = pc.getDouble("xlo") ;
    Double_t xhi = pc.getDouble("xhi") ;
    binning[0] = new RooUniformBinning((xlo==xhi)?getMin():xlo,(xlo==xhi)?getMax():xhi,pc.getInt("nxbins")) ;
    ownBinning[0] = kTRUE ;
  }  else {
    binning[0] = &getBinning() ;
  }

  if (pc.hasProcessed("YVar")) {
    RooAbsRealLValue& yvar = *static_cast<RooAbsRealLValue*>(pc.getObject("yvar")) ;
    vars.add(yvar) ;
    if (pc.hasProcessed("YVar::Binning")) {
      binning[1] = static_cast<RooAbsBinning*>(pc.getObject("ybinning")) ;
    } else if (pc.hasProcessed("YVar::BinningName")) {
      binning[1] = &yvar.getBinning(pc.getString("ybinningName",0,kTRUE)) ;
    } else if (pc.hasProcessed("YVar::BinningSpec")) {
      Double_t ylo = pc.getDouble("ylo") ;
      Double_t yhi = pc.getDouble("yhi") ;
      binning[1] = new RooUniformBinning((ylo==yhi)?yvar.getMin():ylo,(ylo==yhi)?yvar.getMax():yhi,pc.getInt("nybins")) ;
      ownBinning[1] = kTRUE ;
    } else {
      binning[1] = &yvar.getBinning() ;
    }
  }

  if (pc.hasProcessed("ZVar")) {
    RooAbsRealLValue& zvar = *static_cast<RooAbsRealLValue*>(pc.getObject("zvar")) ;
    vars.add(zvar) ;
    if (pc.hasProcessed("ZVar::Binning")) {
      binning[2] = static_cast<RooAbsBinning*>(pc.getObject("zbinning")) ;
    } else if (pc.hasProcessed("ZVar::BinningName")) {
      binning[2] = &zvar.getBinning(pc.getString("zbinningName",0,kTRUE)) ;
    } else if (pc.hasProcessed("ZVar::BinningSpec")) {
      Double_t zlo = pc.getDouble("zlo") ;
      Double_t zhi = pc.getDouble("zhi") ;
      binning[2] = new RooUniformBinning((zlo==zhi)?zvar.getMin():zlo,(zlo==zhi)?zvar.getMax():zhi,pc.getInt("nzbins")) ;
      ownBinning[2] = kTRUE ;
    } else {
      binning[2] = &zvar.getBinning() ;
    }
  }


  TH1* ret = createHistogram(name, vars, axisLabel, binning) ;

  if (ownBinning[0]) delete binning[0] ;
  if (ownBinning[1]) delete binning[1] ;
  if (ownBinning[2]) delete binning[2] ;
  
  return ret ;
}



//_____________________________________________________________________________
TH1F *RooAbsRealLValue::createHistogram(const char *name, const char *yAxisLabel) const 
{
  // Create an empty 1D-histogram with appropriate scale and labels for this variable.
  // This method uses the default plot range which can be changed using the
  // setPlotMin(),setPlotMax() methods, and the default binning which can be
  // changed with setPlotBins(). The caller takes ownership of the returned
  // object and is responsible for deleting it.

  // Check if the fit range is usable as plot range
  if (!fitRangeOKForPlotting()) {
    coutE(InputArguments) << "RooAbsRealLValue::createHistogram(" << GetName() 
			  << ") ERROR: fit range empty or open ended, must explicitly specify range" << endl ;
    return 0 ;
  }

  RooArgList list(*this) ;
  Double_t xlo = getMin() ;
  Double_t xhi = getMax() ;
  Int_t nbins = getBins() ;
  return (TH1F*)createHistogram(name, list, yAxisLabel, &xlo, &xhi, &nbins);
}



//_____________________________________________________________________________
TH1F *RooAbsRealLValue::createHistogram(const char *name, const char *yAxisLabel, Double_t xlo, Double_t xhi, Int_t nBins) const 
{
  // Create an empty 1D-histogram with appropriate scale and labels for this variable.
  // This method uses the default plot range which can be changed using the
  // setPlotMin(),setPlotMax() methods, and the default binning which can be
  // changed with setPlotBins(). The caller takes ownership of the returned
  // object and is responsible for deleting it.

  RooArgList list(*this) ;
  return (TH1F*)createHistogram(name, list, yAxisLabel, &xlo, &xhi, &nBins);
}



//_____________________________________________________________________________
TH1F *RooAbsRealLValue::createHistogram(const char *name, const char *yAxisLabel, const RooAbsBinning& bins) const 
{
  // Create an empty 1D-histogram with appropriate scale and labels for this variable.

  RooArgList list(*this) ;
  const RooAbsBinning* pbins = &bins ;
  return (TH1F*)createHistogram(name, list, yAxisLabel, &pbins);
}



//_____________________________________________________________________________
TH2F *RooAbsRealLValue::createHistogram(const char *name, const RooAbsRealLValue &yvar, const char *zAxisLabel, 
					Double_t* xlo, Double_t* xhi, Int_t* nBins) const 
{
  // Create an empty 2D-histogram with appropriate scale and labels for this variable (x)
  // and the specified y variable. This method uses the default plot ranges for x and y which
  // can be changed using the setPlotMin(),setPlotMax() methods, and the default binning which
  // can be changed with setPlotBins(). The caller takes ownership of the returned object
  // and is responsible for deleting it.

  if ((!xlo && xhi) || (xlo && !xhi)) {
    coutE(InputArguments) << "RooAbsRealLValue::createHistogram(" << GetName() 
			  << ") ERROR must specify either no range, or both limits" << endl ;
    return 0 ;
  }

  Double_t xlo_fit[2] ;
  Double_t xhi_fit[2] ;
  Int_t nbins_fit[2] ;

  Double_t *xlo2 = xlo;
  Double_t *xhi2 = xhi;
  Int_t *nBins2 = nBins;

  if (!xlo2) {

    if (!fitRangeOKForPlotting()) {
      coutE(InputArguments) << "RooAbsRealLValue::createHistogram(" << GetName() 
	   << ") ERROR: fit range empty or open ended, must explicitly specify range" << endl ;      
      return 0 ;
    }
    if (!yvar.fitRangeOKForPlotting()) {
      coutE(InputArguments) << "RooAbsRealLValue::createHistogram(" << GetName() 
	   << ") ERROR: fit range of " << yvar.GetName() << " empty or open ended, must explicitly specify range" << endl ;      
      return 0 ;
    }

    xlo_fit[0] = getMin() ;
    xhi_fit[0] = getMax() ;    

    xlo_fit[1] = yvar.getMin() ;
    xhi_fit[1] = yvar.getMax() ;

    xlo2 = xlo_fit ;
    xhi2 = xhi_fit ;
  }
  
  if (!nBins2) {
    nbins_fit[0] = getBins() ;
    nbins_fit[1] = yvar.getBins() ;
    nBins2 = nbins_fit ;
  }


  RooArgList list(*this,yvar) ;
  return (TH2F*)createHistogram(name, list, zAxisLabel, xlo2, xhi2, nBins2);
}



//_____________________________________________________________________________
TH2F *RooAbsRealLValue::createHistogram(const char *name, const RooAbsRealLValue &yvar, 
					const char *zAxisLabel, const RooAbsBinning** bins) const 
{
  // Create an empty 2D-histogram with appropriate scale and labels for this variable (x)
  // and the specified y variable. 

  RooArgList list(*this,yvar) ;
  return (TH2F*)createHistogram(name, list, zAxisLabel, bins);
}



//_____________________________________________________________________________
TH3F *RooAbsRealLValue::createHistogram(const char *name, const RooAbsRealLValue &yvar, const RooAbsRealLValue &zvar,
					const char *tAxisLabel, Double_t* xlo, Double_t* xhi, Int_t* nBins) const 
{
  // Create an empty 3D-histogram with appropriate scale and labels for this variable (x)
  // and the specified y,z variables. This method uses the default plot ranges for x,y,z which
  // can be changed using the setPlotMin(),setPlotMax() methods, and the default binning which
  // can be changed with setPlotBins(). The caller takes ownership of the returned object
  // and is responsible for deleting it.

  if ((!xlo && xhi) || (xlo && !xhi)) {
    coutE(InputArguments) << "RooAbsRealLValue::createHistogram(" << GetName() 
			  << ") ERROR must specify either no range, or both limits" << endl ;
    return 0 ;
  }

  Double_t xlo_fit[3] ;
  Double_t xhi_fit[3] ;
  Int_t nbins_fit[3] ;

  Double_t *xlo2 = xlo;
  Double_t *xhi2 = xhi;
  Int_t* nBins2 = nBins;
  if (!xlo2) {

    if (!fitRangeOKForPlotting()) {
      coutE(InputArguments) << "RooAbsRealLValue::createHistogram(" << GetName() 
			    << ") ERROR: fit range empty or open ended, must explicitly specify range" << endl ;      
      return 0 ;
    }
    if (!yvar.fitRangeOKForPlotting()) {
      coutE(InputArguments) << "RooAbsRealLValue::createHistogram(" << GetName() 
			    << ") ERROR: fit range of " << yvar.GetName() << " empty or open ended, must explicitly specify range" << endl ;      
      return 0 ;
    }
    if (!zvar.fitRangeOKForPlotting()) {
      coutE(InputArguments) << "RooAbsRealLValue::createHistogram(" << GetName() 
			    << ") ERROR: fit range of " << zvar.GetName() << " empty or open ended, must explicitly specify range" << endl ;      
      return 0 ;
    }

    xlo_fit[0] = getMin() ;
    xhi_fit[0] = getMax() ;    

    xlo_fit[1] = yvar.getMin() ;
    xhi_fit[1] = yvar.getMax() ;

    xlo_fit[2] = zvar.getMin() ;
    xhi_fit[2] = zvar.getMax() ;

    xlo2 = xlo_fit ;
    xhi2 = xhi_fit ;
  }
  
  if (!nBins2) {
    nbins_fit[0] = getBins() ;
    nbins_fit[1] = yvar.getBins() ;
    nbins_fit[2] = zvar.getBins() ;
    nBins2 = nbins_fit ;
  }

  RooArgList list(*this,yvar,zvar) ;
  return (TH3F*)createHistogram(name, list, tAxisLabel, xlo2, xhi2, nBins2);
}


TH3F *RooAbsRealLValue::createHistogram(const char *name, const RooAbsRealLValue &yvar, const RooAbsRealLValue &zvar, 
					const char* tAxisLabel, const RooAbsBinning** bins) const 
{
  // Create an empty 3D-histogram with appropriate scale and labels for this variable (x)
  // and the specified y,z variables. 

  RooArgList list(*this,yvar,zvar) ;
  return (TH3F*)createHistogram(name, list, tAxisLabel, bins);
}




//_____________________________________________________________________________
TH1 *RooAbsRealLValue::createHistogram(const char *name, RooArgList &vars, const char *tAxisLabel, 
				       Double_t* xlo, Double_t* xhi, Int_t* nBins)
{
  // Create 1-, 2- or 3-d ROOT histogram with labels taken
  // from the variables in 'vars' and the with range and binning
  // specified in xlo,xhi and nBins. The dimensions of the arrays xlo,xhi,
  // nBins should match the number of objects in vars.

  const RooAbsBinning* bin[3] ;
  Int_t ndim = vars.getSize() ;
  bin[0] = new RooUniformBinning(xlo[0],xhi[0],nBins[0]) ;
  bin[1] = (ndim>1) ? new RooUniformBinning(xlo[1],xhi[1],nBins[1]) : 0 ;
  bin[2] = (ndim>2) ? new RooUniformBinning(xlo[2],xhi[2],nBins[2]) : 0 ;

  TH1* ret = createHistogram(name,vars,tAxisLabel,bin) ;

  if (bin[0]) delete bin[0] ;
  if (bin[1]) delete bin[1] ;
  if (bin[2]) delete bin[2] ;
  return ret ;  
}



//_____________________________________________________________________________
TH1 *RooAbsRealLValue::createHistogram(const char *name, RooArgList &vars, const char *tAxisLabel, const RooAbsBinning** bins) 
{
  // Create a 1,2, or 3D-histogram with appropriate scale and labels.
  // Binning and ranges are taken from the variables themselves and can be changed by
  // calling their setPlotMin/Max() and setPlotBins() methods. A histogram can be filled
  // using RooAbsReal::fillHistogram() or RooTreeData::fillHistogram().
  // The caller takes ownership of the returned object and is responsible for deleting it.

  // Check that we have 1-3 vars
  Int_t dim= vars.getSize();
  if(dim < 1 || dim > 3) {
    oocoutE((TObject*)0,InputArguments) << "RooAbsReal::createHistogram: dimension not supported: " << dim << endl;
    return 0;
  }

  // Check that all variables are AbsReals and prepare a name of the form <name>_<var1>_...
  TString histName(name);
  histName.Append("_");
  const RooAbsRealLValue *xyz[3];

  Int_t index;
  for(index= 0; index < dim; index++) {
    const RooAbsArg *arg= vars.at(index);
    xyz[index]= dynamic_cast<const RooAbsRealLValue*>(arg);
    if(!xyz[index]) {
      oocoutE((TObject*)0,InputArguments) << "RooAbsRealLValue::createHistogram: variable is not real lvalue: " << arg->GetName() << endl;
      return 0;
    }
    histName.Append("_");
    histName.Append(arg->GetName());
  }
  TString histTitle(histName);
  histTitle.Prepend("Histogram of ");

  // Create the histogram
  TH1 *histogram = 0;
  switch(dim) {
  case 1:
    histogram= new TH1F(histName.Data(), histTitle.Data(),
			bins[0]->numBins(),bins[0]->array());
    break;
  case 2:
    histogram= new TH2F(histName.Data(), histTitle.Data(),
			bins[0]->numBins(),bins[0]->array(),
			bins[1]->numBins(),bins[1]->array());
    break;
  case 3:
    histogram= new TH3F(histName.Data(), histTitle.Data(),
			bins[0]->numBins(),bins[0]->array(),
			bins[1]->numBins(),bins[1]->array(),
			bins[2]->numBins(),bins[2]->array());
    break;
  default:
    assert(0);
    break;
  }
  if(!histogram) {
    oocoutE((TObject*)0,InputArguments) << "RooAbsReal::createHistogram: unable to create a new histogram" << endl;
    return 0;
  }

  // Set the histogram coordinate axis labels from the titles of each variable, adding units if necessary.
  for(index= 0; index < dim; index++) {
    TString axisTitle(xyz[index]->getTitle(kTRUE));
    switch(index) {
    case 0:
      histogram->SetXTitle(axisTitle.Data());
      break;
    case 1:
      histogram->SetYTitle(axisTitle.Data());
      break;
    case 2:
      histogram->SetZTitle(axisTitle.Data());
      break;
    default:
      assert(0);
      break;
    }
  }

  // Set the t-axis title if given one
  if((0 != tAxisLabel) && (0 != strlen(tAxisLabel))) {
    TString axisTitle(tAxisLabel);
    axisTitle.Append(" / ( ");
    for(Int_t index2= 0; index2 < dim; index2++) {
      Double_t delta= bins[index2]->averageBinWidth() ; // xyz[index2]->getBins();
      if(index2 > 0) axisTitle.Append(" x ");
      axisTitle.Append(Form("%g",delta));
      if(strlen(xyz[index2]->getUnit())) {
	axisTitle.Append(" ");
	axisTitle.Append(xyz[index2]->getUnit());
      }
    }
    axisTitle.Append(" )");
    switch(dim) {
    case 1:
      histogram->SetYTitle(axisTitle.Data());
      break;
    case 2:
      histogram->SetZTitle(axisTitle.Data());
      break;
    case 3:
      // not supported in TH1
      break;
    default:
      assert(0);
      break;
    }
  }

  return histogram;
}


Bool_t RooAbsRealLValue::isJacobianOK(const RooArgSet&) const 
{ 
  // Interface function to indicate that this lvalue
  // has a unit or constant jacobian terms with respect to
  // the observable passed as argument. This default implementation
  // always returns true (i.e. jacobian is constant)
  return kTRUE ; 
}