RooLinearVar.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)             *
 *****************************************************************************/
 
//////////////////////////////////////////////////////////////////////////////
/// \class RooLinearVar
/// RooLinearVar is the most general form of a derived real-valued object that can
/// be used by RooRealIntegral to integrate over. The requirements for this are
/// * Can be modified directly (i.e. invertible formula)
/// * Jacobian term in integral is constant (but not necessarily 1)
///
/// This class implements the most general form that satisfies these requirements
/// \f[
///    RLV = \mathrm{slope} \cdot x + \mathrm{offset}
/// \f]
/// \f$ x \f$ is required to be a RooRealVar to meet the invertibility criterium,
/// `slope` and `offset` are RooAbsReals, but cannot overlap with \f$ x \f$,
/// *i.e.*, \f$ x \f$ may not be a server of `slope` and `offset`.
///
/// In the context of a dataset, `slope` may not contain any real-valued dependents
/// (to satisfyt the constant Jacobian requirement). This check cannot be enforced at
/// construction time, but can be performed at run time through the isJacobianOK(depList)
/// member function.
///
///
 
#include <cmath>
 
#include "TClass.h"
#include "RooLinearVar.h"
#include "RooStreamParser.h"
#include "RooArgSet.h"
#include "RooRealVar.h"
#include "RooNumber.h"
#include "RooBinning.h"
#include "RooMsgService.h"
 
 
ClassImp(RooLinearVar);
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor with RooAbsRealLValue variable and RooAbsReal slope and offset
 
RooLinearVar::RooLinearVar(const char *name, const char *title, RooAbsRealLValue& variable,
            const RooAbsReal& slope, const RooAbsReal& offs, const char *unit) :
  RooAbsRealLValue(name, title, unit),
  _binning(variable.getBinning(),slope.getVal(),offs.getVal()),
  _var("var","variable",this,variable,true,true),
  _slope("slope","slope",this,(RooAbsReal&)slope),
  _offset("offset","offset",this,(RooAbsReal&)offs)
{
  // Slope and offset may not depend on variable
  if (slope.dependsOnValue(variable) || offs.dependsOnValue(variable)) {
    std::stringstream ss;
    ss << "RooLinearVar::RooLinearVar(" << GetName()
       << "): ERROR, slope(" << slope.GetName() << ") and offset("
       << offs.GetName() << ") may not depend on variable("
       << variable.GetName() << ")";
    const std::string errMsg = ss.str();
    coutE(InputArguments) << errMsg << std::endl;
    throw std::invalid_argument(errMsg);
  }
 
  // Initial plot range and number of bins from dependent variable
//   setPlotRange(variable.getPlotMin()*_slope + _offset,
//                variable.getPlotMax()*_slope + _offset) ;
//   setPlotBins(variable.getPlotBins()) ;
 
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor
 
RooLinearVar::RooLinearVar(const RooLinearVar& other, const char* name) :
  RooAbsRealLValue(other,name),
  _binning(other._binning),
  _var("var",this,other._var),
  _slope("slope",this,other._slope),
  _offset("offset",this,other._offset)
{
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor
 
RooLinearVar::~RooLinearVar()
{
  _altBinning.Delete() ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Calculate current value of this object
 
double RooLinearVar::evaluate() const
{
  return _offset + _var * _slope ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Assign given value to linear transformation: sets input variable to (value-offset)/slope
/// If slope is zerom an error message is printed and no assignment is made
 
void RooLinearVar::setVal(double value)
{
  //cout << "RooLinearVar::setVal(" << GetName() << "): new value = " << value << endl ;
 
  // Prevent DIV0 problems
  if (_slope == 0.) {
    coutE(Eval) << "RooLinearVar::setVal(" << GetName() << "): ERROR: slope is zero, cannot invert relation" << std::endl ;
    return ;
  }
 
  // Invert formula 'value = offset + slope*var'
  _var->setVal((value - _offset) / _slope) ;
 
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Returns true if Jacobian term associated with current
/// expression tree is indeed constant.
 
bool RooLinearVar::isJacobianOK(const RooArgSet& depList) const
{
  if (!_var->isJacobianOK(depList)) {
    return false ;
  }
 
  // Check if jacobian has no real-valued dependents
  for(RooAbsArg* arg : depList) {
    if (arg->IsA()->InheritsFrom(RooAbsReal::Class())) {
      if (_slope->dependsOnValue(*arg)) {
//    cout << "RooLinearVar::isJacobianOK(" << GetName() << ") return false because slope depends on value of " << arg->GetName() << endl ;
   return false ;
      }
    }
  }
  //   cout << "RooLinearVar::isJacobianOK(" << GetName() << ") return true" << endl ;
  return true ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return value of Jacobian associated with the transformation
 
double RooLinearVar::jacobian() const
{
  return _slope*_var->jacobian() ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Read object contents from stream
 
bool RooLinearVar::readFromStream(std::istream& /*is*/, bool /*compact*/, bool /*verbose*/)
{
  return true ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Write object contents to stream
 
void RooLinearVar::writeToStream(std::ostream& os, bool compact) const
{
  if (compact) {
    os << getVal() ;
  } else {
    os << _slope->GetName() << " * " << _var->GetName() << " + " << _offset->GetName() ;
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Retrieve binning of this linear transformation. A RooLinearVar does not have its own
/// binnings but uses linearly transformed binnings of the input variable. If a given
/// binning exists on the input variable, it will also exist on this linear transformation,
/// and a binning adaptor object is created on the fly.
 
 RooAbsBinning& RooLinearVar::getBinning(const char* name, bool verbose, bool createOnTheFly)
{
  // Normalization binning
  if (name==nullptr) {
    _binning.updateInput(_var->getBinning(),_slope,_offset) ;
    return _binning ;
  }
 
  // Alternative named range binnings, look for existing translator binning first
  auto* altBinning = static_cast<RooLinTransBinning*>(_altBinning.FindObject(name));
  if (altBinning) {
    altBinning->updateInput(_var->getBinning(name,verbose),_slope,_offset) ;
    return *altBinning ;
  }
 
  // If binning is not found return default binning, if creation is not requested
  if (!_var->hasRange(name) && !createOnTheFly) {
    return _binning ;
  }
 
  // Create translator binning on the fly
  RooAbsBinning& sourceBinning = _var->getBinning(name,verbose) ;
  auto* transBinning = new RooLinTransBinning(sourceBinning,_slope,_offset) ;
  _altBinning.Add(transBinning) ;
 
  return *transBinning ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Const version of getBinning()
 
const RooAbsBinning& RooLinearVar::getBinning(const char* name, bool verbose, bool createOnTheFly) const
{
  return const_cast<RooLinearVar*>(this)->getBinning(name,verbose,createOnTheFly) ;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get a list of all binning names. An empty name implies the default binning.
/// A 0 pointer should be passed to getBinning in this case.
 
std::list<std::string> RooLinearVar::getBinningNames() const
{
  std::list<std::string> binningNames(1, "");
 
  for (TObject const* binning : _altBinning) {
    binningNames.push_back(binning->GetName());
  }
 
  return binningNames;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns true if binning with given name exists.If a given binning
/// exists on the input variable, it will also exists on this linear
/// transformation.
 
bool RooLinearVar::hasBinning(const char* name) const
{
  return _var->hasBinning(name) ;
}