RooAbsPdf.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 RooAbsPdf
    \ingroup Roofitcore
 
## RooAbsPdf, the base class of all PDFs
 
RooAbsPdf is the abstract interface for all probability density
functions. The class provides hybrid analytical/numerical
normalization for its implementations, error tracing and a MC
generator interface.
 
### A Minimal PDF Implementation
 
A minimal implementation of a PDF class derived from RooAbsPdf
should override the `evaluate()` function. This function should
return the PDF's value (which does not need to be normalised).
 
 
#### Normalization/Integration
 
Although the normalization of a PDF is an integral part of a
probability density function, normalization is treated separately
in RooAbsPdf. The reason is that a RooAbsPdf object is more than a
PDF: it can be a building block for a more complex, composite PDF
if any of its variables are functions instead of variables. In
such cases the normalization of the composite may not be simply the
integral over the dependents of the top level PDF as these are
functions with potentially non-trivial Jacobian terms themselves.
\note Therefore, no explicit attempt should be made to normalize the
function output in evaluate(). In particular, normalisation constants
can be omitted to speed up the function evaluations, and included later
in the integration of the PDF (see below), which is called rarely in
comparison to the `evaluate()` function.
 
In addition, RooAbsPdf objects do not have a static concept of what
variables are parameters and what variables are dependents (which
need to be integrated over for a correct PDF normalization).
Instead, the choice of normalization is always specified each time a
normalized value is requested from the PDF via the getVal()
method.
 
RooAbsPdf manages the entire normalization logic of each PDF with
help of a RooRealIntegral object, which coordinates the integration
of a given choice of normalization. By default, RooRealIntegral will
perform a fully numeric integration of all dependents. However,
PDFs can advertise one or more (partial) analytical integrals of
their function, and these will be used by RooRealIntegral, if it
determines that this is safe (i.e. no hidden Jacobian terms,
multiplication with other PDFs that have one or more dependents in
commen etc).
 
#### Implementing analytical integrals
To implement analytical integrals, two functions must be implemented. First,
 
```
Int_t getAnalyticalIntegral(const RooArgSet& integSet, RooArgSet& anaIntSet)
```
should return the analytical integrals that are supported. `integSet`
is the set of dependents for which integration is requested. The
function should copy the subset of dependents it can analytically
integrate to `anaIntSet`, and return a unique identification code for
this integration configuration.  If no integration can be
performed, zero should be returned. Second,
 
```
Double_t analyticalIntegral(Int_t code)
```
 
implements the actual analytical integral(s) advertised by
`getAnalyticalIntegral()`.  This function will only be called with
codes returned by `getAnalyticalIntegral()`, except code zero.
 
The integration range for each dependent to be integrated can
be obtained from the dependent's proxy functions `min()` and
`max()`. Never call these proxy functions for any proxy not known to
be a dependent via the integration code.  Doing so may be
ill-defined, e.g. in case the proxy holds a function, and will
trigger an assert. Integrated category dependents should always be
summed over all of their states.
 
 
 
### Direct generation of observables
 
Distributions for any PDF can be generated with the accept/reject method,
but for certain PDFs, more efficient methods may be implemented. To
implement direct generation of one or more observables, two
functions need to be implemented, similar to those for analytical
integrals:
 
```
Int_t getGenerator(const RooArgSet& generateVars, RooArgSet& directVars)
```
and
```
void generateEvent(Int_t code)
```
 
The first function advertises observables, for which distributions can be generated,
similar to the way analytical integrals are advertised. The second
function implements the actual generator for the advertised observables.
 
The generated dependent values should be stored in the proxy
objects. For this, the assignment operator can be used (i.e. `xProxy
= 3.0` ). Never call assign to any proxy not known to be a dependent
via the generation code.  Doing so may be ill-defined, e.g. in case
the proxy holds a function, and will trigger an assert.
 
 
### Batched function evaluations (Advanced usage)
 
To speed up computations with large numbers of data events in unbinned fits,
it is beneficial to override `evaluateBatch()`. Like this, large batches of
computations can be done, without having to call `evaluate()` for each single data event.
`evaluateBatch()` should execute the same computation as `evaluate()`, but it
may choose an implementation that is capable of SIMD computations.
If evaluateBatch is not implemented, the classic and slower `evaluate()` will be
called for each data event.
*/
 
#include "RooAbsPdf.h"
 
#include "RooFit.h"
#include "RooMsgService.h"
#include "RooDataSet.h"
#include "RooArgSet.h"
#include "RooArgProxy.h"
#include "RooRealProxy.h"
#include "RooRealVar.h"
#include "RooGenContext.h"
#include "RooBinnedGenContext.h"
#include "RooPlot.h"
#include "RooCurve.h"
#include "RooNLLVar.h"
#include "RooMinuit.h"
#include "RooCategory.h"
#include "RooNameReg.h"
#include "RooCmdConfig.h"
#include "RooGlobalFunc.h"
#include "RooAddition.h"
#include "RooRandom.h"
#include "RooNumIntConfig.h"
#include "RooProjectedPdf.h"
#include "RooInt.h"
#include "RooCustomizer.h"
#include "RooConstraintSum.h"
#include "RooParamBinning.h"
#include "RooNumCdf.h"
#include "RooFitResult.h"
#include "RooNumGenConfig.h"
#include "RooCachedReal.h"
#include "RooXYChi2Var.h"
#include "RooChi2Var.h"
#include "RooMinimizer.h"
#include "RooRealIntegral.h"
#include "RooWorkspace.h"
#include "RooNaNPacker.h"
 
#include "RooHelpers.h"
#include "RooVDTHeaders.h"
 
#include "TClass.h"
#include "TMath.h"
#include "TPaveText.h"
#include "TList.h"
#include "TMatrixD.h"
#include "TMatrixDSym.h"
#include "Math/CholeskyDecomp.h"
#include "RooDerivative.h"
 
#include <iostream>
#include <string>
 
using namespace std;
 
ClassImp(RooAbsPdf);
 
ClassImp(RooAbsPdf::GenSpec);
 
 
Int_t RooAbsPdf::_verboseEval = 0;
TString RooAbsPdf::_normRangeOverride;
 
////////////////////////////////////////////////////////////////////////////////
/// Default constructor
 
RooAbsPdf::RooAbsPdf() : _norm(0), _normSet(0), _specGeneratorConfig(0)
{
  _errorCount = 0 ;
  _negCount = 0 ;
  _rawValue = 0 ;
  _selectComp = kFALSE ;
  _traceCount = 0 ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor with name and title only
 
RooAbsPdf::RooAbsPdf(const char *name, const char *title) :
  RooAbsReal(name,title), _norm(0), _normSet(0), _normMgr(this,10), _selectComp(kTRUE), _specGeneratorConfig(0)
{
  resetErrorCounters() ;
  setTraceCounter(0) ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor with name, title, and plot range
 
RooAbsPdf::RooAbsPdf(const char *name, const char *title,
           Double_t plotMin, Double_t plotMax) :
  RooAbsReal(name,title,plotMin,plotMax), _norm(0), _normSet(0), _normMgr(this,10), _selectComp(kTRUE), _specGeneratorConfig(0)
{
  resetErrorCounters() ;
  setTraceCounter(0) ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor
 
RooAbsPdf::RooAbsPdf(const RooAbsPdf& other, const char* name) :
  RooAbsReal(other,name), _norm(0), _normSet(0),
  _normMgr(other._normMgr,this), _selectComp(other._selectComp), _normRange(other._normRange)
{
  resetErrorCounters() ;
  setTraceCounter(other._traceCount) ;
 
  if (other._specGeneratorConfig) {
    _specGeneratorConfig = new RooNumGenConfig(*other._specGeneratorConfig) ;
  } else {
    _specGeneratorConfig = 0 ;
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor
 
RooAbsPdf::~RooAbsPdf()
{
  if (_specGeneratorConfig) delete _specGeneratorConfig ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return current value, normalized by integrating over
/// the observables in `nset`. If `nset` is 0, the unnormalized value
/// is returned. All elements of `nset` must be lvalues.
///
/// Unnormalized values are not cached.
/// Doing so would be complicated as `_norm->getVal()` could
/// spoil the cache and interfere with returning the cached
/// return value. Since unnormalized calls are typically
/// done in integration calls, there is no performance hit.
 
Double_t RooAbsPdf::getValV(const RooArgSet* nset) const
{
 
  // Special handling of case without normalization set (used in numeric integration of pdfs)
  if (!nset) {
    RooArgSet* tmp = _normSet ;
    _normSet = 0 ;
    Double_t val = evaluate() ;
    _normSet = tmp ;
 
    return TMath::IsNaN(val) ? 0. : val;
  }
 
 
  // Process change in last data set used
  Bool_t nsetChanged(kFALSE) ;
  if (nset!=_normSet || _norm==0) {
    nsetChanged = syncNormalization(nset) ;
  }
 
  // Return value of object. Calculated if dirty, otherwise cached value is returned.
  if (isValueDirty() || nsetChanged || _norm->isValueDirty()) {
 
    // Evaluate numerator
    const double rawVal = evaluate();
 
    // Evaluate denominator
    const double normVal = _norm->getVal();
 
    if (normVal < 0. || (normVal == 0. && rawVal != 0)) {
      //Unreasonable normalisations. A zero integral can be tolerated if the function vanishes, though.
      const std::string msg = "p.d.f normalization integral is zero or negative: " + std::to_string(normVal);
      logEvalError(msg.c_str());
      clearValueAndShapeDirty();
      return _value = RooNaNPacker::packFloatIntoNaN(-normVal + (rawVal < 0. ? -rawVal : 0.));
    }
 
    if (rawVal < 0.) {
      logEvalError(Form("p.d.f value is less than zero (%f), trying to recover", rawVal));
      clearValueAndShapeDirty();
      return _value = RooNaNPacker::packFloatIntoNaN(-rawVal);
    }
 
    if (TMath::IsNaN(rawVal)) {
      logEvalError("p.d.f value is Not-a-Number");
      clearValueAndShapeDirty();
      return _value = rawVal;
    }
 
    _value = (rawVal == 0. && normVal == 0.) ? 0. : rawVal / normVal;
 
    clearValueAndShapeDirty();
  }
 
  return _value ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Compute batch of values for given range, and normalise by integrating over
/// the observables in `nset`. If `nset` is `nullptr`, unnormalized values
/// are returned. All elements of `nset` must be lvalues.
///
/// \param[in] begin Begin of the batch.
/// \param[in] maxSize Size of the requested range. May come out smaller.
/// \param[in] normSet   If not nullptr, normalise results by integrating over
/// the variables in this set. The normalisation is only computed once, and applied
/// to the full batch.
///
RooSpan<const double> RooAbsPdf::getValBatch(std::size_t begin, std::size_t maxSize,
    const RooArgSet* normSet) const
{
  // Some PDFs do preprocessing here, e.g. of the norm
  getValV(normSet);
 
  if (_allBatchesDirty || _operMode == ADirty) {
    _batchData.markDirty();
    _allBatchesDirty = false;
  }
 
  // Special handling of case without normalization set (used in numeric integration of pdfs)
  if (!normSet) {
    RooArgSet* tmp = _normSet ;
    _normSet = nullptr;
    auto outputs = evaluateBatch(begin, maxSize);
    maxSize = outputs.size();
    _normSet = tmp;
 
    _batchData.setStatus(begin, maxSize, BatchHelpers::BatchData::kReady);
 
    return outputs;
  }
 
 
  // TODO wait if batch is computing?
  if (_batchData.status(begin, normSet, BatchHelpers::BatchData::kgetVal) <= BatchHelpers::BatchData::kDirty
      || _norm->isValueDirty()) {
 
    auto outputs = evaluateBatch(begin, maxSize);
    maxSize = outputs.size();
 
    // Evaluate denominator
    const double normVal = _norm->getVal();
 
    if (normVal < 0.
        || (normVal == 0. && std::any_of(outputs.begin(), outputs.end(), [](double val){return val != 0;}))) {
      logEvalError(Form("p.d.f normalization integral is zero or negative."
          "\n\tInt(%s) = %f", GetName(), normVal));
    }
 
    if (normVal != 1. && normVal > 0.) {
      const double invNorm = 1./normVal;
      for (double& val : outputs) { //CHECK_VECTORISE
        val *= invNorm;
      }
    }
 
    _batchData.setStatus(begin, maxSize, BatchHelpers::BatchData::kReady);
  }
 
  const auto ret = _batchData.getBatch(begin, maxSize);
 
  return ret;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Compute batch of values for given input data, and normalise by integrating over
/// the observables in `nset`. Store result in `evalData`, and return a span pointing to
/// it.
///
/// If `nset` is `nullptr`, unnormalised values
/// are returned. All elements of `nset` must be lvalues.
///
/// \param[in/out]  evalData Object holding data that should be used in computations.
/// Each array of data is identified by the pointer to the RooFit object that this data belongs to.
/// The object that this function is called on will store its results here as well.
/// \param[in] normSet   If not nullptr, normalise results by integrating over
/// the variables in this set. The normalisation is only computed once, and applied
/// to the full batch.
/// \return RooSpan with probabilities. The memory of this span is owned by `evalData`.
RooSpan<const double> RooAbsPdf::getValues(BatchHelpers::RunContext& evalData, const RooArgSet* normSet) const {
  auto item = evalData.spans.find(this);
  if (item != evalData.spans.end()) {
    return item->second;
  }
 
  auto outputs = evaluateSpan(evalData, normSet);
  assert(evalData.spans.count(this) > 0);
 
  if (normSet != nullptr) {
    if (normSet != _normSet || _norm == nullptr) {
      syncNormalization(normSet);
    }
    // Evaluate denominator
    const double normVal = _norm->getVal();
 
    if (normVal < 0.
        || (normVal == 0. && std::any_of(outputs.begin(), outputs.end(), [](double val){return val != 0;}))) {
      logEvalError(Form("p.d.f normalization integral is zero or negative."
          "\n\tInt(%s) = %f", GetName(), normVal));
    }
 
    if (normVal != 1. && normVal > 0.) {
      const double invNorm = 1./normVal;
      for (double& val : outputs) { //CHECK_VECTORISE
        val *= invNorm;
      }
    }
  }
 
  return outputs;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Analytical integral with normalization (see RooAbsReal::analyticalIntegralWN() for further information)
///
/// This function applies the normalization specified by 'normSet' to the integral returned
/// by RooAbsReal::analyticalIntegral(). The passthrough scenario (code=0) is also changed
/// to return a normalized answer
 
Double_t RooAbsPdf::analyticalIntegralWN(Int_t code, const RooArgSet* normSet, const char* rangeName) const
{
  cxcoutD(Eval) << "RooAbsPdf::analyticalIntegralWN(" << GetName() << ") code = " << code << " normset = " << (normSet?*normSet:RooArgSet()) << endl ;
 
 
  if (code==0) return getVal(normSet) ;
  if (normSet) {
    return analyticalIntegral(code,rangeName) / getNorm(normSet) ;
  } else {
    return analyticalIntegral(code,rangeName) ;
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Check that passed value is positive and not 'not-a-number'.  If
/// not, print an error, until the error counter reaches its set
/// maximum.
 
Bool_t RooAbsPdf::traceEvalPdf(Double_t value) const
{
  // check for a math error or negative value
  Bool_t error(kFALSE) ;
  if (TMath::IsNaN(value)) {
    logEvalError(Form("p.d.f value is Not-a-Number (%f), forcing value to zero",value)) ;
    error=kTRUE ;
  }
  if (value<0) {
    logEvalError(Form("p.d.f value is less than zero (%f), forcing value to zero",value)) ;
    error=kTRUE ;
  }
 
  // do nothing if we are no longer tracing evaluations and there was no error
  if(!error) return error ;
 
  // otherwise, print out this evaluations input values and result
  if(++_errorCount <= 10) {
    cxcoutD(Tracing) << "*** Evaluation Error " << _errorCount << " ";
    if(_errorCount == 10) cxcoutD(Tracing) << "(no more will be printed) ";
  }
  else {
    return error  ;
  }
 
  Print() ;
  return error ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Get normalisation term needed to normalise the raw values returned by
/// getVal(). Note that `getVal(normalisationVariables)` will automatically
/// apply the normalisation term returned here.
/// \param nset Set of variables to normalise over.
Double_t RooAbsPdf::getNorm(const RooArgSet* nset) const
{
  if (!nset) return 1 ;
 
  syncNormalization(nset,kTRUE) ;
  if (_verboseEval>1) cxcoutD(Tracing) << IsA()->GetName() << "::getNorm(" << GetName() << "): norm(" << _norm << ") = " << _norm->getVal() << endl ;
 
  Double_t ret = _norm->getVal() ;
  if (ret==0.) {
    if(++_errorCount <= 10) {
      coutW(Eval) << "RooAbsPdf::getNorm(" << GetName() << ":: WARNING normalization is zero, nset = " ;  nset->Print("1") ;
      if(_errorCount == 10) coutW(Eval) << "RooAbsPdf::getNorm(" << GetName() << ") INFO: no more messages will be printed " << endl ;
    }
  }
 
  return ret ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return pointer to RooAbsReal object that implements calculation of integral over observables iset in range
/// rangeName, optionally taking the integrand normalized over observables nset
 
const RooAbsReal* RooAbsPdf::getNormObj(const RooArgSet* nset, const RooArgSet* iset, const TNamed* rangeName) const
{
 
  // Check normalization is already stored
  CacheElem* cache = (CacheElem*) _normMgr.getObj(nset,iset,0,rangeName) ;
  if (cache) {
    return cache->_norm ;
  }
 
  // If not create it now
  RooArgSet* depList = getObservables(iset) ;
  RooAbsReal* norm = createIntegral(*depList,*nset, *getIntegratorConfig(), RooNameReg::str(rangeName)) ;
  delete depList ;
 
  // Store it in the cache
  cache = new CacheElem(*norm) ;
  _normMgr.setObj(nset,iset,cache,rangeName) ;
 
  // And return the newly created integral
  return norm ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Verify that the normalization integral cached with this PDF
/// is valid for given set of normalization observables.
///
/// If not, the cached normalization integral (if any) is deleted
/// and a new integral is constructed for use with 'nset'.
/// Elements in 'nset' can be discrete and real, but must be lvalues.
///
/// For functions that declare to be self-normalized by overloading the
/// selfNormalized() function, a unit normalization is always constructed.
 
Bool_t RooAbsPdf::syncNormalization(const RooArgSet* nset, Bool_t adjustProxies) const
{
 
//   cout << IsA()->GetName() << "::syncNormalization(" << GetName() << ") nset = " << nset << " = " << (nset?*nset:RooArgSet()) << endl ;
 
  _normSet = (RooArgSet*) nset ;
 
  // Check if data sets are identical
  CacheElem* cache = (CacheElem*) _normMgr.getObj(nset) ;
  if (cache) {
 
    Bool_t nsetChanged = (_norm!=cache->_norm) ;
    _norm = cache->_norm ;
 
 
//      cout << "returning existing object " << _norm->GetName() << endl ;
 
    if (nsetChanged && adjustProxies) {
      // Update dataset pointers of proxies
      ((RooAbsPdf*) this)->setProxyNormSet(nset) ;
    }
 
    return nsetChanged ;
  }
 
  // Update dataset pointers of proxies
  if (adjustProxies) {
    ((RooAbsPdf*) this)->setProxyNormSet(nset) ;
  }
 
  std::unique_ptr<RooArgSet> depList(getObservables(nset));
 
  if (_verboseEval>0) {
    if (!selfNormalized()) {
      cxcoutD(Tracing) << IsA()->GetName() << "::syncNormalization(" << GetName()
      << ") recreating normalization integral " << endl ;
      if (depList) depList->printStream(ccoutD(Tracing),kName|kValue|kArgs,kSingleLine) ; else ccoutD(Tracing) << "<none>" << endl ;
    } else {
      cxcoutD(Tracing) << IsA()->GetName() << "::syncNormalization(" << GetName() << ") selfNormalized, creating unit norm" << endl;
    }
  }
 
  // Destroy old normalization & create new
  if (selfNormalized() || !dependsOn(*depList)) {
    TString ntitle(GetTitle()) ; ntitle.Append(" Unit Normalization") ;
    TString nname(GetName()) ; nname.Append("_UnitNorm") ;
    _norm = new RooRealVar(nname.Data(),ntitle.Data(),1) ;
  } else {
    const char* nr = (_normRangeOverride.Length()>0 ? _normRangeOverride.Data() : (_normRange.Length()>0 ? _normRange.Data() : 0)) ;
 
//     cout << "RooAbsPdf::syncNormalization(" << GetName() << ") rangeName for normalization is " << (nr?nr:"<null>") << endl ;
    RooAbsReal* normInt = createIntegral(*depList,*getIntegratorConfig(),nr) ;
    normInt->getVal() ;
//     cout << "resulting normInt = " << normInt->GetName() << endl ;
 
    const char* cacheParamsStr = getStringAttribute("CACHEPARAMINT") ;
    if (cacheParamsStr && strlen(cacheParamsStr)) {
 
      RooArgSet* intParams = normInt->getVariables() ;
 
      RooNameSet cacheParamNames ;
      cacheParamNames.setNameList(cacheParamsStr) ;
      RooArgSet* cacheParams = cacheParamNames.select(*intParams) ;
 
      if (cacheParams->getSize()>0) {
   cxcoutD(Caching) << "RooAbsReal::createIntObj(" << GetName() << ") INFO: constructing " << cacheParams->getSize()
          << "-dim value cache for integral over " << *depList << " as a function of " << *cacheParams << " in range " << (nr?nr:"<default>") <<  endl ;
   string name = Form("%s_CACHE_[%s]",normInt->GetName(),cacheParams->contentsString().c_str()) ;
   RooCachedReal* cachedIntegral = new RooCachedReal(name.c_str(),name.c_str(),*normInt,*cacheParams) ;
   cachedIntegral->setInterpolationOrder(2) ;
   cachedIntegral->addOwnedComponents(*normInt) ;
   cachedIntegral->setCacheSource(kTRUE) ;
   if (normInt->operMode()==ADirty) {
     cachedIntegral->setOperMode(ADirty) ;
   }
   normInt= cachedIntegral ;
      }
 
      delete cacheParams ;
      delete intParams ;
    }
    _norm = normInt ;
  }
 
  // Register new normalization with manager (takes ownership)
  cache = new CacheElem(*_norm) ;
  _normMgr.setObj(nset,cache) ;
 
//   cout << "making new object " << _norm->GetName() << endl ;
 
  return kTRUE ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Reset error counter to given value, limiting the number
/// of future error messages for this pdf to 'resetValue'
 
void RooAbsPdf::resetErrorCounters(Int_t resetValue)
{
  _errorCount = resetValue ;
  _negCount   = resetValue ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Reset trace counter to given value, limiting the
/// number of future trace messages for this pdf to 'value'
 
void RooAbsPdf::setTraceCounter(Int_t value, Bool_t allNodes)
{
  if (!allNodes) {
    _traceCount = value ;
    return ;
  } else {
    RooArgList branchList ;
    branchNodeServerList(&branchList) ;
    TIterator* iter = branchList.createIterator() ;
    RooAbsArg* arg ;
    while((arg=(RooAbsArg*)iter->Next())) {
      RooAbsPdf* pdf = dynamic_cast<RooAbsPdf*>(arg) ;
      if (pdf) pdf->setTraceCounter(value,kFALSE) ;
    }
    delete iter ;
  }
 
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return the log of the current value with given normalization
/// An error message is printed if the argument of the log is negative.
 
Double_t RooAbsPdf::getLogVal(const RooArgSet* nset) const
{
  Double_t prob = getVal(nset) ;
 
  if (fabs(prob)>1e6) {
    coutW(Eval) << "RooAbsPdf::getLogVal(" << GetName() << ") WARNING: large likelihood value: " << prob << endl ;
  }
 
  if(prob < 0) {
    logEvalError("getLogVal() top-level p.d.f evaluates to a negative number") ;
    return RooNaNPacker::packFloatIntoNaN(-prob);
  }
 
  if(prob == 0) {
    logEvalError("getLogVal() top-level p.d.f evaluates to zero") ;
 
    return -std::numeric_limits<double>::infinity();
  }
 
  if (TMath::IsNaN(prob)) {
    logEvalError("getLogVal() top-level p.d.f evaluates to NaN") ;
 
    return prob;
  }
 
  return log(prob);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Check for infinity or NaN.
/// \param[in] inputs Array to check
/// \return True if either infinity or NaN were found.
namespace {
template<class T>
bool checkInfNaNNeg(const T& inputs) {
  // check for a math error or negative value
  bool inf = false;
  bool nan = false;
  bool neg = false;
 
  for (double val : inputs) { //CHECK_VECTORISE
    inf |= !std::isfinite(val);
    nan |= TMath::IsNaN(val); // Works also during fast math
    neg |= val < 0;
  }
 
  return inf || nan || neg;
}
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Scan through outputs and fix+log all nans and negative values.
/// \param[in,out] outputs Array to be scanned & fixed.
/// \param[in] begin Begin of event range. Only needed to print the correct event number
/// where the error occurred.
void RooAbsPdf::logBatchComputationErrors(RooSpan<const double>& outputs, std::size_t begin) const {
  for (unsigned int i=0; i<outputs.size(); ++i) {
    const double value = outputs[i];
    if (TMath::IsNaN(outputs[i])) {
      logEvalError(Form("p.d.f value of (%s) is Not-a-Number (%f) for entry %zu",
          GetName(), value, begin+i));
    } else if (!std::isfinite(outputs[i])){
      logEvalError(Form("p.d.f value of (%s) is (%f) for entry %zu",
          GetName(), value, begin+i));
    } else if (outputs[i] < 0.) {
      logEvalError(Form("p.d.f value of (%s) is less than zero (%f) for entry %zu",
          GetName(), value, begin+i));
    }
  }
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Compute the log-likelihoods for all events in the requested batch.
/// The arguments are passed over to getValBatch().
/// \param[in] begin Start of the batch.
/// \param[in] maxSize  Maximum size of the batch. Depending on data layout and memory, the batch
/// may come back smaller.
/// \return    Returns a batch of doubles that contains the log probabilities.
RooSpan<const double> RooAbsPdf::getLogValBatch(std::size_t begin, std::size_t maxSize,
    const RooArgSet* normSet) const
{
  auto pdfValues = getValBatch(begin, maxSize, normSet);
 
  if (checkInfNaNNeg(pdfValues)) {
    logBatchComputationErrors(pdfValues, begin);
  }
 
  auto output = _batchData.makeWritableBatchUnInit(begin, pdfValues.size(),
      normSet, BatchHelpers::BatchData::kgetLogVal);
 
  for (std::size_t i = 0; i < pdfValues.size(); ++i) { //CHECK_VECTORISE
    const double prob = pdfValues[i];
 
    double theLog = _rf_fast_log(prob);
 
    if (prob < 0) {
      theLog = std::numeric_limits<double>::quiet_NaN();
    } else if (prob == 0 || TMath::IsNaN(prob)) {
      theLog = -std::numeric_limits<double>::infinity();
    }
 
    output[i] = theLog;
  }
 
  return output;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Compute the log-likelihoods for all events in the requested batch.
/// The arguments are passed over to getValBatch().
/// \param[in] evalData Struct with data that should be used for evaluation.
/// \param[in] normSet Optional normalisation set to be used during computations.
/// \return    Returns a batch of doubles that contains the log probabilities.
RooSpan<const double> RooAbsPdf::getLogProbabilities(BatchHelpers::RunContext& evalData, const RooArgSet* normSet) const
{
  auto pdfValues = getValues(evalData, normSet);
 
  if (checkInfNaNNeg(pdfValues)) {
    logBatchComputationErrors(pdfValues, 0);
  }
 
  evalData.logProbabilities.resize(pdfValues.size());
  RooSpan<double> output( evalData.logProbabilities );
 
  for (std::size_t i = 0; i < pdfValues.size(); ++i) { //CHECK_VECTORISE
    const double prob = pdfValues[i];
 
    double theLog = _rf_fast_log(prob);
 
    if (prob < 0) {
      theLog = std::numeric_limits<double>::quiet_NaN();
    } else if (prob == 0 || TMath::IsNaN(prob)) {
      theLog = -std::numeric_limits<double>::infinity();
    }
 
    output[i] = theLog;
  }
 
  return output;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the extended likelihood term (\f$ N_\mathrm{expect} - N_\mathrm{observed} \cdot \log(N_\mathrm{expect} \f$)
/// of this PDF for the given number of observed events.
///
/// For successful operation, the PDF implementation must indicate that
/// it is extendable by overloading `canBeExtended()`, and must
/// implement the `expectedEvents()` function.
 
Double_t RooAbsPdf::extendedTerm(Double_t observed, const RooArgSet* nset) const
{
  // check if this PDF supports extended maximum likelihood fits
  if(!canBeExtended()) {
    coutE(InputArguments) << fName << ": this PDF does not support extended maximum likelihood"
         << endl;
    return 0;
  }
 
  Double_t expected= expectedEvents(nset);
  if(expected < 0) {
    coutE(InputArguments) << fName << ": calculated negative expected events: " << expected
         << endl;
    return 0;
  }
 
 
  // Explicitly handle case Nobs=Nexp=0
  if (fabs(expected)<1e-10 && fabs(observed)<1e-10) {
    return 0 ;
  }
 
  // Check for errors in Nexpected
  if (expected<0 || TMath::IsNaN(expected)) {
    logEvalError("extendedTerm #expected events is <0 or NaN") ;
    return 0 ;
  }
 
  // calculate and return the negative log-likelihood of the Poisson
  // factor for this dataset, dropping the constant log(observed!)
  //   Double_t extra=0;
  //   if(observed<1000000) {
  //     Double_t Delta1 = (expected-observed);
  //     Double_t Delta2 = observed*(log(expected)-log(observed+1));
  //     Double_t Const3 = 0.5*log(observed+1);
  //     extra= Delta1 - Delta2 + Const3;
 
  //     cout << " extra obs = " << observed << " exp = " << expected << endl ;
  //     cout << " extra orig = " << expected - observed*log(expected) << endl ;
  //     cout << " extra orig fix = " << expected - observed*log(expected) + log(TMath::Gamma(observed+1)) << endl ;
  //     cout << " extra new  = " << extra << endl ;
 
  //   } else {
  //     Double_t sigma_square=expected;
  //     Double_t diff=observed-expected;
  //     extra=-log(sigma_square)/2 + (diff*diff)/(2*sigma_square);
  //   }
 
  Double_t extra= expected - observed*log(expected);
 
//   cout << "RooAbsPdf::extendedTerm(" << GetName() << ") observed = " << observed << " expected = " << expected << endl ;
 
  Bool_t trace(kFALSE) ;
  if(trace) {
    cxcoutD(Tracing) << fName << "::extendedTerm: expected " << expected << " events, got "
           << observed << " events. extendedTerm = " << extra << endl;
  }
 
//   cout << "RooAbsPdf::extendedTerm(" << GetName() << ") nExp = " << expected << " nObs = " << observed << endl ;
  return extra;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Construct representation of -log(L) of PDF with given dataset. If dataset is unbinned, an unbinned likelihood is constructed. If the dataset
/// is binned, a binned likelihood is constructed.
///
/// The following named arguments are supported
///
/// <table>
/// <tr><th> Type of CmdArg    <th>    Effect on nll
/// <tr><td> `ConditionalObservables(const RooArgSet& set)` <td> Do not normalize PDF over listed observables
/// <tr><td> `Extended(Bool_t flag)`           <td> Add extended likelihood term, off by default
/// <tr><td> `Range(const char* name)`         <td> Fit only data inside range with given name
/// <tr><td> `Range(Double_t lo, Double_t hi)` <td> Fit only data inside given range. A range named "fit" is created on the fly on all observables.
///                                               Multiple comma separated range names can be specified.
/// <tr><td> `SumCoefRange(const char* name)`  <td> Set the range in which to interpret the coefficients of RooAddPdf components
/// <tr><td> `NumCPU(int num, int strat)`      <td> Parallelize NLL calculation on num CPUs
///   <table>
///   <tr><th> Strategy   <th> Effect
///   <tr><td> 0 = RooFit::BulkPartition (Default) <td> Divide events in N equal chunks
///   <tr><td> 1 = RooFit::Interleave <td> Process event i%N in process N. Recommended for binned data with
///                     a substantial number of zero-bins, which will be distributed across processes more equitably in this strategy
///   <tr><td> 2 = RooFit::SimComponents <td> Process each component likelihood of a RooSimultaneous fully in a single process
///                     and distribute components over processes. This approach can be benificial if normalization calculation time
///                     dominates the total computation time of a component (since the normalization calculation must be performed
///                     in each process in strategies 0 and 1. However beware that if the RooSimultaneous components do not share many
///                     parameters this strategy is inefficient: as most minuit-induced likelihood calculations involve changing
///                     a single parameter, only 1 of the N processes will be active most of the time if RooSimultaneous components
///                     do not share many parameters
///   <tr><td> 3 = RooFit::Hybrid <td> Follow strategy 0 for all RooSimultaneous components, except those with less than
///                     30 dataset entries, for which strategy 2 is followed.
///   </table>
/// <tr><td> `BatchMode(bool on)`              <td> Batch evaluation mode. See fitTo().
/// <tr><td> `Optimize(Bool_t flag)`           <td> Activate constant term optimization (on by default)
/// <tr><td> `SplitRange(Bool_t flag)`         <td> Use separate fit ranges in a simultaneous fit. Actual range name for each subsample is assumed to
///                                               be `rangeName_indexState`, where `indexState` is the state of the master index category of the simultaneous fit.
/// Using `Range("range"), SplitRange()` as switches, different ranges could be set like this:
/// ```
/// myVariable.setRange("range_pi0", 135, 210);
/// myVariable.setRange("range_gamma", 50, 210);
/// ```
/// <tr><td> `Constrain(const RooArgSet&pars)`          <td> For p.d.f.s that contain internal parameter constraint terms (that is usually product PDFs, where one
///     term of the product depends on parameters but not on the observable(s),), only apply constraints to the given subset of parameters.
/// <tr><td> `ExternalConstraints(const RooArgSet& )`   <td> Include given external constraints to likelihood by multiplying them with the original likelihood.
/// <tr><td> `GlobalObservables(const RooArgSet&)`      <td> Define the set of normalization observables to be used for the constraint terms.
///                                                        If none are specified the constrained parameters are used.
/// <tr><td> `GlobalObservablesTag(const char* tagName)` <td> Define the set of normalization observables to be used for the constraint terms by
///                                                         a string attribute associated with pdf observables that match the given tagName.
/// <tr><td> `Verbose(Bool_t flag)`           <td> Controls RooFit informational messages in likelihood construction
/// <tr><td> `CloneData(Bool flag)`           <td> Use clone of dataset in NLL (default is true)
/// <tr><td> `Offset(Bool_t)`                 <td> Offset likelihood by initial value (so that starting value of FCN in minuit is zero).
///                                              This can improve numeric stability in simultaneous fits with components with large likelihood values
/// </table>
///
///
 
RooAbsReal* RooAbsPdf::createNLL(RooAbsData& data, const RooCmdArg& arg1, const RooCmdArg& arg2, const RooCmdArg& arg3, const RooCmdArg& arg4,
                                             const RooCmdArg& arg5, const RooCmdArg& arg6, const RooCmdArg& arg7, const RooCmdArg& arg8)
{
  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 createNLL(data,l) ;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Construct representation of -log(L) of PDFwith given dataset. If dataset is unbinned, an unbinned likelihood is constructed. If the dataset
/// is binned, a binned likelihood is constructed.
///
/// See RooAbsPdf::createNLL(RooAbsData& data, RooCmdArg arg1, RooCmdArg arg2, RooCmdArg arg3, RooCmdArg arg4,
///                                    RooCmdArg arg5, RooCmdArg arg6, RooCmdArg arg7, RooCmdArg arg8)
/// for documentation of options
 
RooAbsReal* RooAbsPdf::createNLL(RooAbsData& data, const RooLinkedList& cmdList)
{
 
  // Select the pdf-specific commands
  RooCmdConfig pc(Form("RooAbsPdf::createNLL(%s)",GetName())) ;
 
  pc.defineString("rangeName","RangeWithName",0,"",kTRUE) ;
  pc.defineString("addCoefRange","SumCoefRange",0,"") ;
  pc.defineString("globstag","GlobalObservablesTag",0,"") ;
  pc.defineDouble("rangeLo","Range",0,-999.) ;
  pc.defineDouble("rangeHi","Range",1,-999.) ;
  pc.defineInt("splitRange","SplitRange",0,0) ;
  pc.defineInt("ext","Extended",0,2) ;
  pc.defineInt("numcpu","NumCPU",0,1) ;
  pc.defineInt("interleave","NumCPU",1,0) ;
  pc.defineInt("verbose","Verbose",0,0) ;
  pc.defineInt("optConst","Optimize",0,0) ;
  pc.defineInt("cloneData","CloneData", 0, 2);
  pc.defineSet("projDepSet","ProjectedObservables",0,0) ;
  pc.defineSet("cPars","Constrain",0,0) ;
  pc.defineSet("glObs","GlobalObservables",0,0) ;
//  pc.defineInt("constrAll","Constrained",0,0) ;
  pc.defineInt("doOffset","OffsetLikelihood",0,0) ;
  pc.defineSet("extCons","ExternalConstraints",0,0) ;
  pc.defineInt("BatchMode", "BatchMode", 0, 0);
  pc.defineMutex("Range","RangeWithName") ;
//  pc.defineMutex("Constrain","Constrained") ;
  pc.defineMutex("GlobalObservables","GlobalObservablesTag") ;
 
  // Process and check varargs
  pc.process(cmdList) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }
 
  // Decode command line arguments
  const char* rangeName = pc.getString("rangeName",0,kTRUE) ;
  const char* addCoefRangeName = pc.getString("addCoefRange",0,kTRUE) ;
  const char* globsTag = pc.getString("globstag",0,kTRUE) ;
  Int_t ext      = pc.getInt("ext") ;
  Int_t numcpu   = pc.getInt("numcpu") ;
  Int_t numcpu_strategy = pc.getInt("interleave");
  // strategy 3 works only for RooSimultaneus.
  if (numcpu_strategy==3 && !this->InheritsFrom("RooSimultaneous") ) {
     coutW(Minimization) << "Cannot use a NumCpu Strategy = 3 when the pdf is not a RooSimultaneus, "
                            "falling back to default strategy = 0"  << endl;
     numcpu_strategy = 0;
  }
  RooFit::MPSplit interl = (RooFit::MPSplit) numcpu_strategy;
 
  Int_t splitr   = pc.getInt("splitRange") ;
  Bool_t verbose = pc.getInt("verbose") ;
  Int_t optConst = pc.getInt("optConst") ;
  Int_t cloneData = pc.getInt("cloneData") ;
  Int_t doOffset = pc.getInt("doOffset") ;
 
  // If no explicit cloneData command is specified, cloneData is set to true if optimization is activated
  if (cloneData==2) {
    cloneData = optConst ;
  }
 
 
  RooArgSet* cPars = pc.getSet("cPars") ;
  RooArgSet* glObs = pc.getSet("glObs") ;
  if (pc.hasProcessed("GlobalObservablesTag")) {
    if (glObs) delete glObs ;
    RooArgSet* allVars = getVariables() ;
    glObs = (RooArgSet*) allVars->selectByAttrib(globsTag,kTRUE) ;
    coutI(Minimization) << "User-defined specification of global observables definition with tag named '" <<  globsTag << "'" << endl ;
    delete allVars ;
  } else if (!pc.hasProcessed("GlobalObservables")) {
 
    // Neither GlobalObservables nor GlobalObservablesTag has been processed - try if a default tag is defined in the head node
    // Check if head not specifies default global observable tag
    const char* defGlobObsTag = getStringAttribute("DefaultGlobalObservablesTag") ;
    if (defGlobObsTag) {
      coutI(Minimization) << "p.d.f. provides built-in specification of global observables definition with tag named '" <<  defGlobObsTag << "'" << endl ;
      if (glObs) delete glObs ;
      RooArgSet* allVars = getVariables() ;
      glObs = (RooArgSet*) allVars->selectByAttrib(defGlobObsTag,kTRUE) ;
    }
  }
 
 
  Bool_t doStripDisconnected=kFALSE ;
 
  // If no explicit list of parameters to be constrained is specified apply default algorithm
  // All terms of RooProdPdfs that do not contain observables and share a parameters with one or more
  // terms that do contain observables are added as constraints.
  if (!cPars) {
    cPars = getParameters(data,kFALSE) ;
    doStripDisconnected=kTRUE ;
  }
  const RooArgSet* extCons = pc.getSet("extCons") ;
 
  // Process automatic extended option
  if (ext==2) {
    ext = ((extendMode()==CanBeExtended || extendMode()==MustBeExtended)) ? 1 : 0 ;
    if (ext) {
      coutI(Minimization) << "p.d.f. provides expected number of events, including extended term in likelihood." << endl ;
    }
  }
 
  // Clear possible range attributes from previous fits.
  setStringAttribute("fitrange", nullptr);
 
  if (pc.hasProcessed("Range")) {
    Double_t rangeLo = pc.getDouble("rangeLo") ;
    Double_t rangeHi = pc.getDouble("rangeHi") ;
 
    // Create range with name 'fit' with above limits on all observables
    RooArgSet* obs = getObservables(&data) ;
    for (auto arg : *obs) {
      RooRealVar* rrv =  dynamic_cast<RooRealVar*>(arg) ;
      if (rrv) rrv->setRange("fit",rangeLo,rangeHi) ;
    }
 
    // Set range name to be fitted to "fit"
    rangeName = "fit" ;
  }
 
  RooArgSet projDeps ;
  RooArgSet* tmp = pc.getSet("projDepSet") ;
  if (tmp) {
    projDeps.add(*tmp) ;
  }
 
  // Construct NLL
  RooAbsReal::setEvalErrorLoggingMode(RooAbsReal::CollectErrors) ;
  RooAbsReal* nll ;
  string baseName = Form("nll_%s_%s",GetName(),data.GetName()) ;
  if (!rangeName || strchr(rangeName,',')==0) {
    // Simple case: default range, or single restricted range
    //cout<<"FK: Data test 1: "<<data.sumEntries()<<endl;
 
    auto theNLL = new RooNLLVar(baseName.c_str(),"-log(likelihood)",
        *this,data,projDeps,ext,rangeName,addCoefRangeName,numcpu,interl,
        verbose,splitr,cloneData);
    theNLL->batchMode(pc.getInt("BatchMode"));
    nll = theNLL;
  } else {
    // Composite case: multiple ranges
    RooArgList nllList ;
    auto tokens = RooHelpers::tokenise(rangeName, ",");
    for (const auto& token : tokens) {
      auto nllComp = new RooNLLVar(Form("%s_%s",baseName.c_str(),token.c_str()),"-log(likelihood)",
          *this,data,projDeps,ext,token.c_str(),addCoefRangeName,numcpu,interl,
          verbose,splitr,cloneData);
      nllComp->batchMode(pc.getInt("BatchMode"));
      nllList.add(*nllComp) ;
    }
    nll = new RooAddition(baseName.c_str(),"-log(likelihood)",nllList,kTRUE) ;
  }
  RooAbsReal::setEvalErrorLoggingMode(RooAbsReal::PrintErrors) ;
 
  // Collect internal and external constraint specifications
  RooArgSet allConstraints ;
 
  if (_myws && _myws->set(Form("CACHE_CONSTR_OF_PDF_%s_FOR_OBS_%s", GetName(), RooNameSet(*data.get()).content()))) {
 
     // retrieve from cache
     const RooArgSet *constr =
        _myws->set(Form("CACHE_CONSTR_OF_PDF_%s_FOR_OBS_%s", GetName(), RooNameSet(*data.get()).content()));
     coutI(Minimization) << "createNLL picked up cached constraints from workspace with " << constr->getSize()
                         << " entries" << endl;
     allConstraints.add(*constr);
 
  } else {
 
     if (cPars && cPars->getSize() > 0) {
        RooArgSet *constraints = getAllConstraints(*data.get(), *cPars, doStripDisconnected);
        allConstraints.add(*constraints);
        delete constraints;
     }
     if (extCons) {
        allConstraints.add(*extCons);
     }
 
     // write to cache
     if (_myws) {
        // cout << "createNLL: creating cache for allconstraints=" << allConstraints << endl ;
        coutI(Minimization) << "createNLL: caching constraint set under name "
                            << Form("CONSTR_OF_PDF_%s_FOR_OBS_%s", GetName(), RooNameSet(*data.get()).content())
                            << " with " << allConstraints.getSize() << " entries" << endl;
        _myws->defineSetInternal(
           Form("CACHE_CONSTR_OF_PDF_%s_FOR_OBS_%s", GetName(), RooNameSet(*data.get()).content()), allConstraints);
     }
  }
 
  // Include constraints, if any, in likelihood
  RooAbsReal* nllCons(0) ;
  if (allConstraints.getSize()>0 && cPars) {
 
    coutI(Minimization) << " Including the following constraint terms in minimization: " << allConstraints << endl ;
    if (glObs) {
      coutI(Minimization) << "The following global observables have been defined: " << *glObs << endl ;
    }
    nllCons = new RooConstraintSum(Form("%s_constr",baseName.c_str()),"nllCons",allConstraints,glObs ? *glObs : *cPars) ;
    nllCons->setOperMode(ADirty) ;
    RooAbsReal* orignll = nll ;
 
    nll = new RooAddition(Form("%s_with_constr",baseName.c_str()),"nllWithCons",RooArgSet(*nll,*nllCons)) ;
    nll->addOwnedComponents(RooArgSet(*orignll,*nllCons)) ;
  }
 
 
  if (optConst) {
    nll->constOptimizeTestStatistic(RooAbsArg::Activate,optConst>1) ;
  }
 
  if (doStripDisconnected) {
    delete cPars ;
  }
 
  if (doOffset) {
    nll->enableOffsetting(kTRUE) ;
  }
 
  return nll ;
}
 
 
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Fit PDF to given dataset. If dataset is unbinned, an unbinned maximum likelihood is performed. If the dataset
/// is binned, a binned maximum likelihood is performed. By default the fit is executed through the MINUIT
/// commands MIGRAD, HESSE in succession.
/// \param[in] data  Data to fit the PDF to
/// \param[in] arg1  One or more arguments to control the behaviour of the fit
/// \return RooFitResult with fit status and parameters if option Save() is used, `nullptr` otherwise. The user takes ownership of the fit result.
///
/// The following named arguments are supported
///
/// <table>
/// <tr><th> Type of CmdArg                  <th> Options to control construction of -log(L)
/// <tr><td> `ConditionalObservables(const RooArgSet& set)`  <td>  Do not normalize PDF over listed observables
/// <tr><td> `Extended(Bool_t flag)`           <td>  Add extended likelihood term, off by default
/// <tr><td> `Range(const char* name)`         <td>  Fit only data inside range with given name. Multiple comma-separated range names can be specified.
/// <tr><td> `Range(Double_t lo, Double_t hi)` <td>  Fit only data inside given range. A range named "fit" is created on the fly on all observables.
/// <tr><td> `SumCoefRange(const char* name)`  <td>  Set the range in which to interpret the coefficients of RooAddPdf components
/// <tr><td> `NumCPU(int num, int strat)`      <td> Parallelize NLL calculation on `num` CPUs
///   <table>
///   <tr><th> Strategy   <th> Effect
///   <tr><td> 0 = RooFit::BulkPartition (Default) <td> Divide events in N equal chunks
///   <tr><td> 1 = RooFit::Interleave <td> Process event i%N in process N. Recommended for binned data with
///                     a substantial number of zero-bins, which will be distributed across processes more equitably in this strategy
///   <tr><td> 2 = RooFit::SimComponents <td> Process each component likelihood of a RooSimultaneous fully in a single process
///                     and distribute components over processes. This approach can be benificial if normalization calculation time
///                     dominates the total computation time of a component (since the normalization calculation must be performed
///                     in each process in strategies 0 and 1. However beware that if the RooSimultaneous components do not share many
///                     parameters this strategy is inefficient: as most minuit-induced likelihood calculations involve changing
///                     a single parameter, only 1 of the N processes will be active most of the time if RooSimultaneous components
///                     do not share many parameters
///   <tr><td> 3 = RooFit::Hybrid <td> Follow strategy 0 for all RooSimultaneous components, except those with less than
///                     30 dataset entries, for which strategy 2 is followed.
///   </table>
/// <tr><td> `SplitRange(Bool_t flag)`          <td>  Use separate fit ranges in a simultaneous fit. Actual range name for each subsample is assumed
///                                                 to by `rangeName_indexState` where indexState is the state of the master index category of the simultaneous fit.
/// Using `Range("range"), SplitRange()` as switches, different ranges could be set like this:
/// ```
/// myVariable.setRange("range_pi0", 135, 210);
/// myVariable.setRange("range_gamma", 50, 210);
/// ```
/// <tr><td> `Constrain(const RooArgSet&pars)`          <td> For p.d.f.s that contain internal parameter constraint terms (that is usually product PDFs, where one
///     term of the product depends on parameters but not on the observable(s),), only apply constraints to the given subset of parameters.
/// <tr><td> `ExternalConstraints(const RooArgSet& )`   <td> Include given external constraints to likelihood by multiplying them with the original likelihood.
/// <tr><td> `GlobalObservables(const RooArgSet&)`      <td> Define the set of normalization observables to be used for the constraint terms.
///                                                        If none are specified the constrained parameters are used.
/// <tr><td> `Offset(Bool_t)`                           <td>  Offset likelihood by initial value (so that starting value of FCN in minuit is zero).
///                                                         This can improve numeric stability in simultaneously fits with components with large likelihood values
/// <tr><td> `BatchMode(bool on)`                       <td> **Experimental** batch evaluation mode. This computes a batch of likelihood values at a time,
///                                                          uses faster math functions and possibly auto vectorisation (this depends on the compiler flags).
///                                                          Depending on hardware capabilities, the compiler flags and whether a batch evaluation function was
///                                                          implemented for the PDFs of the model, likelihood computations are 2x to 10x faster.
///                                                          The relative difference of the single log-likelihoods w.r.t. the legacy mode is usually better than 1.E-12,
///                                                          and fit parameters usually agree to better than 1.E-6.
///
/// <tr><th><th> Options to control flow of fit procedure
/// <tr><td> `Minimizer(type,algo)`   <td>  Choose minimization package and algorithm to use. Default is MINUIT/MIGRAD through the RooMinimizer interface,
///                                       but others can be specified (through RooMinimizer interface). Select OldMinuit to use MINUIT through the old RooMinuit interface
///   <table>
///   <tr><th> Type         <th> Algorithm
///   <tr><td> OldMinuit    <td>  migrad, simplex, minimize (=migrad+simplex), migradimproved (=migrad+improve)
///   <tr><td> Minuit       <td>  migrad, simplex, minimize (=migrad+simplex), migradimproved (=migrad+improve)
///   <tr><td> Minuit2      <td>  migrad, simplex, minimize, scan
///   <tr><td> GSLMultiMin  <td>  conjugatefr, conjugatepr, bfgs, bfgs2, steepestdescent
///   <tr><td> GSLSimAn     <td>  -
///   </table>
///
/// <tr><td> `InitialHesse(Bool_t flag)`       <td>  Flag controls if HESSE before MIGRAD as well, off by default
/// <tr><td> `Optimize(Bool_t flag)`           <td>  Activate constant term optimization of test statistic during minimization (on by default)
/// <tr><td> `Hesse(Bool_t flag)`              <td>  Flag controls if HESSE is run after MIGRAD, on by default
/// <tr><td> `Minos(Bool_t flag)`              <td>  Flag controls if MINOS is run after HESSE, off by default
/// <tr><td> `Minos(const RooArgSet& set)`     <td>  Only run MINOS on given subset of arguments
/// <tr><td> `Save(Bool_t flag)`               <td>  Flag controls if RooFitResult object is produced and returned, off by default
/// <tr><td> `Strategy(Int_t flag)`            <td>  Set Minuit strategy (0 to 2, default is 1)
/// <tr><td> `EvalErrorWall(bool flag=true)`    <td>  When parameters are in disallowed regions (e.g. PDF is negative), return very high value to fitter
///                                                  to force it out of that region. This can, however, mean that the fitter gets lost in this region. If
///                                                  this happens, try switching it off.
/// <tr><td> `RecoverFromUndefinedRegions(double strength)` <td> When PDF is invalid (e.g. parameter in undefined region), try to direct minimiser away from that region.
///                                                              `strength` controls the magnitude of the penalty term. Leaving out this argument defaults to 10. Switch off with `strength = 0.`.
/// <tr><td> `FitOptions(const char* optStr)`  <td>  \deprecated Steer fit with classic options string (for backward compatibility).
///                                                \attention Use of this option excludes use of any of the new style steering options.
///
/// <tr><td> `SumW2Error(Bool_t flag)`         <td>  Apply correction to errors and covariance matrix.
///       This uses two covariance matrices, one with the weights, the other with squared weights,
///       to obtain the correct errors for weighted likelihood fits. If this option is activated, the
///       corrected covariance matrix is calculated as \f$ V_\mathrm{corr} = V C^{-1} V \f$, where \f$ V \f$ is the original
///       covariance matrix and \f$ C \f$ is the inverse of the covariance matrix calculated using the
///       squared weights. This allows to switch between two interpretations of errors:
///       <table>
///       <tr><th> SumW2Error <th> Interpretation
///       <tr><td> true       <td> The errors reflect the uncertainty of the Monte Carlo simulation.
///                                Use this if you want to know how much accuracy you can get from the available Monte Carlo statistics.
///
///                                **Example**: Simulation with 1000 events, the average weight is 0.1.
///                                The errors are as big as if one fitted to 1000 events.
///       <tr><td> false      <td> The errors reflect the errors of a dataset, which is as big as the sum of weights.
///                                Use this if you want to know what statistical errors you would get if you had a dataset with as many
///                                events as the (weighted) Monte Carlo simulation represents.
///
///                                **Example** (Data as above):
///                                The errors are as big as if one fitted to 100 events.
///       </table>
/// <tr><td> `AsymptoticError()`               <td> Use the asymptotically correct approach to estimate errors in the presence of weights.
///                                                 This is slower but more accurate than `SumW2Error`. See also https://arxiv.org/abs/1911.01303).
/// <tr><td> `PrefitDataFraction(double fraction)`
///                                            <td>  Runs a prefit on a small dataset of size fraction*(actual data size). This can speed up fits
///                                                  by finding good starting values for the parameters for the actual fit.
///                                                  \warning Prefitting may give bad results when used in binned analysis.
///
/// <tr><th><th> Options to control informational output
/// <tr><td> `Verbose(Bool_t flag)`            <td>  Flag controls if verbose output is printed (NLL, parameter changes during fit).
/// <tr><td> `Timer(Bool_t flag)`              <td>  Time CPU and wall clock consumption of fit steps, off by default.
/// <tr><td> `PrintLevel(Int_t level)`         <td>  Set Minuit print level (-1 to 3, default is 1). At -1 all RooFit informational messages are suppressed as well.
///                                                  See RooMinimizer::PrintLevel for the meaning of the levels.
/// <tr><td> `Warnings(Bool_t flag)`           <td>  Enable or disable MINUIT warnings (enabled by default)
/// <tr><td> `PrintEvalErrors(Int_t numErr)`   <td>  Control number of p.d.f evaluation errors printed per likelihood evaluation.
///                                                A negative value suppresses output completely, a zero value will only print the error count per p.d.f component,
///                                                a positive value will print details of each error up to `numErr` messages per p.d.f component.
/// </table>
///
 
RooFitResult* RooAbsPdf::fitTo(RooAbsData& data, const RooCmdArg& arg1, const RooCmdArg& arg2, const RooCmdArg& arg3, const RooCmdArg& arg4,
                                                 const RooCmdArg& arg5, const RooCmdArg& arg6, const RooCmdArg& arg7, const RooCmdArg& arg8)
{
  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 fitTo(data,l) ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Fit PDF to given dataset. If dataset is unbinned, an unbinned maximum likelihood is performed. If the dataset
/// is binned, a binned maximum likelihood is performed. By default the fit is executed through the MINUIT
/// commands MIGRAD, HESSE and MINOS in succession.
///
/// See RooAbsPdf::fitTo(RooAbsData&,RooCmdArg&,RooCmdArg&,RooCmdArg&,RooCmdArg&,RooCmdArg&,RooCmdArg&,RooCmdArg&,RooCmdArg&)
///
/// for documentation of options
 
RooFitResult* RooAbsPdf::fitTo(RooAbsData& data, const RooLinkedList& cmdList)
{
  // Select the pdf-specific commands
  RooCmdConfig pc(Form("RooAbsPdf::fitTo(%s)",GetName())) ;
 
  RooLinkedList fitCmdList(cmdList) ;
  RooLinkedList nllCmdList = pc.filterCmdList(fitCmdList,"ProjectedObservables,Extended,Range,"
      "RangeWithName,SumCoefRange,NumCPU,SplitRange,Constrained,Constrain,ExternalConstraints,"
      "CloneData,GlobalObservables,GlobalObservablesTag,OffsetLikelihood,BatchMode");
 
  pc.defineDouble("prefit", "Prefit",0,0);
  pc.defineDouble("RecoverFromUndefinedRegions", "RecoverFromUndefinedRegions",0,10.);
  pc.defineString("fitOpt","FitOptions",0,"") ;
  pc.defineInt("optConst","Optimize",0,2) ;
  pc.defineInt("verbose","Verbose",0,0) ;
  pc.defineInt("doSave","Save",0,0) ;
  pc.defineInt("doTimer","Timer",0,0) ;
  pc.defineInt("plevel","PrintLevel",0,1) ;
  pc.defineInt("strat","Strategy",0,1) ;
  pc.defineInt("initHesse","InitialHesse",0,0) ;
  pc.defineInt("hesse","Hesse",0,1) ;
  pc.defineInt("minos","Minos",0,0) ;
  pc.defineInt("ext","Extended",0,2) ;
  pc.defineInt("numcpu","NumCPU",0,1) ;
  pc.defineInt("numee","PrintEvalErrors",0,10) ;
  pc.defineInt("doEEWall","EvalErrorWall",0,1) ;
  pc.defineInt("doWarn","Warnings",0,1) ;
  pc.defineInt("doSumW2","SumW2Error",0,-1) ;
  pc.defineInt("doAsymptoticError","AsymptoticError",0,-1) ;
  pc.defineInt("doOffset","OffsetLikelihood",0,0) ;
  pc.defineString("mintype","Minimizer",0,"Minuit") ;
  pc.defineString("minalg","Minimizer",1,"minuit") ;
  pc.defineObject("minosSet","Minos",0,0) ;
  pc.defineSet("cPars","Constrain",0,0) ;
  pc.defineSet("extCons","ExternalConstraints",0,0) ;
  pc.defineMutex("FitOptions","Verbose") ;
  pc.defineMutex("FitOptions","Save") ;
  pc.defineMutex("FitOptions","Timer") ;
  pc.defineMutex("FitOptions","Strategy") ;
  pc.defineMutex("FitOptions","InitialHesse") ;
  pc.defineMutex("FitOptions","Hesse") ;
  pc.defineMutex("FitOptions","Minos") ;
  pc.defineMutex("Range","RangeWithName") ;
  pc.defineMutex("InitialHesse","Minimizer") ;
 
  // Process and check varargs
  pc.process(fitCmdList) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }
 
  // Decode command line arguments
  Double_t prefit = pc.getDouble("prefit");
  const double recoverFromNaN = pc.getDouble("RecoverFromUndefinedRegions");
  const char* fitOpt = pc.getString("fitOpt",0,kTRUE) ;
  Int_t optConst = pc.getInt("optConst") ;
  Int_t verbose  = pc.getInt("verbose") ;
  Int_t doSave   = pc.getInt("doSave") ;
  Int_t doTimer  = pc.getInt("doTimer") ;
  Int_t plevel    = pc.getInt("plevel") ;
  Int_t strat    = pc.getInt("strat") ;
  Int_t initHesse= pc.getInt("initHesse") ;
  Int_t hesse    = pc.getInt("hesse") ;
  Int_t minos    = pc.getInt("minos") ;
  Int_t numee    = pc.getInt("numee") ;
  Int_t doEEWall = pc.getInt("doEEWall") ;
  Int_t doWarn   = pc.getInt("doWarn") ;
  Int_t doSumW2  = pc.getInt("doSumW2") ;
  Int_t doAsymptotic = pc.getInt("doAsymptoticError");
  const RooArgSet* minosSet = static_cast<RooArgSet*>(pc.getObject("minosSet")) ;
#ifdef __ROOFIT_NOROOMINIMIZER
  const char* minType =0 ;
#else
  const char* minType = pc.getString("mintype","Minuit") ;
  const char* minAlg = pc.getString("minalg","minuit") ;
#endif
 
  if (optConst > 1) {
    // optConst >= 2 is pre-computating values, which are never used when
    // the batchMode is on. This just wastes time.
 
    RooCmdConfig conf(Form("RooAbsPdf::fitTo(%s)", GetName()));
    conf.defineInt("BatchMode","BatchMode",0,0);
    conf.allowUndefined(true);
    conf.process(nllCmdList);
    if (conf.getInt("BatchMode") != 0) {
      optConst = 1;
    }
  }
 
 
  // Determine if the dataset has weights
  Bool_t weightedData = data.isNonPoissonWeighted() ;
 
  // Warn user that a method to determine parameter uncertainties should be provided if weighted data is offered
  if (weightedData && doSumW2==-1 && doAsymptotic==-1) {
    coutW(InputArguments) << "RooAbsPdf::fitTo(" << GetName() << ") WARNING: a likelihood fit is requested of what appears to be weighted data.\n"
                          << "       While the estimated values of the parameters will always be calculated taking the weights into account,\n"
           << "       there are multiple ways to estimate the errors of the parameters. You are advised to make an \n"
           << "       explicit choice for the error calculation:\n"
           << "           - Either provide SumW2Error(true), to calculate a sum-of-weights-corrected HESSE error matrix\n"
           << "             (error will be proportional to the number of events in MC).\n"
           << "           - Or provide SumW2Error(false), to return errors from original HESSE error matrix\n"
           << "             (which will be proportional to the sum of the weights, i.e., a dataset with <sum of weights> events).\n"
           << "           - Or provide AsymptoticError(true), to use the asymptotically correct expression\n"
           << "             (for details see https://arxiv.org/abs/1911.01303)."
           << endl ;
  }
 
 
  // Warn user that sum-of-weights correction does not apply to MINOS errrors
  if (doSumW2==1 && minos) {
    coutW(InputArguments) << "RooAbsPdf::fitTo(" << GetName() << ") WARNING: sum-of-weights correction does not apply to MINOS errors" << endl ;
  }
  if (doAsymptotic==1 && minos) {
      coutW(InputArguments) << "RooAbsPdf::fitTo(" << GetName() << ") WARNING: asymptotic correction does not apply to MINOS errors" << endl ;
    }
 
  if (prefit != 0)  {
    size_t nEvents = static_cast<size_t>(prefit*data.numEntries());
    if (prefit > 0.5 || nEvents < 100)  {
      oocoutW(this,InputArguments) << "PrefitDataFraction should be in suitable range."
      << "With the current PrefitDataFraction=" << prefit
      << ", the number of events would be " << nEvents<< " out of "
      << data.numEntries() << ". Skipping prefit..." << endl;
    }
    else {
      size_t step = data.numEntries()/nEvents;
      RooArgSet tinyVars(*data.get());
      RooRealVar weight("weight","weight",1);
 
      if (data.isWeighted()) tinyVars.add(weight);
 
      RooDataSet tiny("tiny", "tiny", tinyVars,
          data.isWeighted() ? RooFit::WeightVar(weight) : RooCmdArg());
 
      for (int i=0; i<data.numEntries(); i+=step)
      {
        const RooArgSet *event = data.get(i);
        tiny.add(*event, data.weight());
      }
      RooLinkedList tinyCmdList(cmdList) ;
      pc.filterCmdList(tinyCmdList,"Prefit,Hesse,Minos,Verbose,Save,Timer");
      RooCmdArg hesse_option = RooFit::Hesse(false);
      RooCmdArg print_option = RooFit::PrintLevel(-1);
 
      tinyCmdList.Add(&hesse_option);
      tinyCmdList.Add(&print_option);
 
      fitTo(tiny,tinyCmdList);
    }
  }
 
  RooAbsReal* nll = createNLL(data,nllCmdList) ;
  RooFitResult *ret = 0 ;
 
  //avoid setting both SumW2 and Asymptotic for uncertainty correction
  if (doSumW2==1 && doAsymptotic==1) {
      coutE(InputArguments) << "RooAbsPdf::fitTo(" << GetName() << ") ERROR: Cannot compute both asymptotically correct and SumW2 errors." << endl ;
      return ret;
    }
 
  // Instantiate MINUIT
 
  if (string(minType)!="OldMinuit") {
 
#ifndef __ROOFIT_NOROOMINIMIZER
    RooMinimizer m(*nll) ;
 
    m.setMinimizerType(minType) ;
 
    m.setEvalErrorWall(doEEWall) ;
    m.setRecoverFromNaNStrength(recoverFromNaN);
    if (doWarn==0) {
      // m.setNoWarn() ; WVE FIX THIS
    }
 
    m.setPrintEvalErrors(numee) ;
    if (plevel!=1) {
      m.setPrintLevel(plevel) ;
    }
 
    if (optConst) {
      // Activate constant term optimization
      m.optimizeConst(optConst) ;
    }
 
    if (fitOpt) {
 
      // Play fit options as historically defined
      ret = m.fit(fitOpt) ;
 
    } else {
 
      if (verbose) {
   // Activate verbose options
   m.setVerbose(1) ;
      }
      if (doTimer) {
   // Activate timer options
   m.setProfile(1) ;
      }
 
      if (strat!=1) {
   // Modify fit strategy
   m.setStrategy(strat) ;
      }
 
      if (initHesse) {
   // Initialize errors with hesse
   m.hesse() ;
      }
 
      // Minimize using chosen algorithm
      m.minimize(minType,minAlg) ;
 
      if (hesse) {
   // Evaluate errors with Hesse
   m.hesse() ;
      }
 
      //asymptotically correct approach
      if (doAsymptotic==1 && m.getNPar()>0) {
   //Calculated corrected errors for weighted likelihood fits
   std::unique_ptr<RooFitResult> rw(m.save());
   //Weighted inverse Hessian matrix
   const TMatrixDSym& matV = rw->covarianceMatrix();
   coutI(Fitting) << "RooAbsPdf::fitTo(" << GetName() << ") Calculating covariance matrix according to the asymptotically correct approach. If you find this method useful please consider citing https://arxiv.org/abs/1911.01303." << endl;
 
   //Initialise matrix containing first derivatives
   TMatrixDSym num(rw->floatParsFinal().getSize());
   for (int k=0; k<rw->floatParsFinal().getSize(); k++)
      for (int l=0; l<rw->floatParsFinal().getSize(); l++)
         num(k,l) = 0.0;
   RooArgSet* obs = getObservables(data);
   //Create derivative objects
   std::vector<std::unique_ptr<RooDerivative> > derivatives;
   const RooArgList& floated = rw->floatParsFinal();
   std::unique_ptr<RooArgSet> floatingparams( (RooArgSet*)getParameters(data)->selectByAttrib("Constant", false) );
   for (const auto paramresult : floated) {
      auto paraminternal = static_cast<RooRealVar*>(floatingparams->find(*paramresult));
      assert(floatingparams->find(*paramresult)->IsA() == RooRealVar::Class());
      std::unique_ptr<RooDerivative> deriv( derivative(*paraminternal, *obs, 1) );
      derivatives.push_back(std::move(deriv));
   }
 
   //Loop over data
   for (int j=0; j<data.numEntries(); j++) {
      //Sets obs to current data point, this is where the pdf will be evaluated
      *obs = *data.get(j);
      //Determine first derivatives
      std::vector<Double_t> diffs(floated.getSize(), 0.0);
      for (int k=0; k < floated.getSize(); k++) {
         const auto paramresult = static_cast<RooRealVar*>(floated.at(k));
         auto paraminternal = static_cast<RooRealVar*>(floatingparams->find(*paramresult));
         //first derivative to parameter k at best estimate point for this measurement
         Double_t diff = derivatives.at(k)->getVal();
         //need to reset to best fit point after differentiation
         *paraminternal = paramresult->getVal();
         diffs.at(k) = diff;
      }
      //Fill numerator matrix
      Double_t prob = getVal(obs);
      for (int k=0; k<floated.getSize(); k++) {
         for (int l=0; l<floated.getSize(); l++) {
            num(k,l) += data.weight()*data.weight()*diffs.at(k)*diffs.at(l)/(prob*prob);
         }
      }
   }
   num.Similarity(matV);
 
   //Propagate corrected errors to parameters objects
   m.applyCovarianceMatrix(num);
      }
 
      if (doSumW2==1 && m.getNPar()>0) {
   // Make list of RooNLLVar components of FCN
   RooArgSet* comps = nll->getComponents();
   vector<RooNLLVar*> nllComponents;
   nllComponents.reserve(comps->getSize());
   TIterator* citer = comps->createIterator();
   RooAbsArg* arg;
   while ((arg=(RooAbsArg*)citer->Next())) {
     RooNLLVar* nllComp = dynamic_cast<RooNLLVar*>(arg);
     if (!nllComp) continue;
     nllComponents.push_back(nllComp);
   }
   delete citer;
   delete comps;
 
   // Calculated corrected errors for weighted likelihood fits
   RooFitResult* rw = m.save();
   for (vector<RooNLLVar*>::iterator it = nllComponents.begin(); nllComponents.end() != it; ++it) {
     (*it)->applyWeightSquared(kTRUE);
   }
   coutI(Fitting) << "RooAbsPdf::fitTo(" << GetName() << ") Calculating sum-of-weights-squared correction matrix for covariance matrix" << endl ;
   m.hesse();
   RooFitResult* rw2 = m.save();
   for (vector<RooNLLVar*>::iterator it = nllComponents.begin(); nllComponents.end() != it; ++it) {
     (*it)->applyWeightSquared(kFALSE);
   }
 
   // Apply correction matrix
   const TMatrixDSym& matV = rw->covarianceMatrix();
   TMatrixDSym matC = rw2->covarianceMatrix();
   using ROOT::Math::CholeskyDecompGenDim;
   CholeskyDecompGenDim<Double_t> decomp(matC.GetNrows(), matC);
   if (!decomp) {
     coutE(Fitting) << "RooAbsPdf::fitTo(" << GetName()
          << ") ERROR: Cannot apply sum-of-weights correction to covariance matrix: correction matrix calculated with weight-squared is singular" <<endl ;
   } else {
     // replace C by its inverse
     decomp.Invert(matC);
     // the class lies about the matrix being symmetric, so fill in the
     // part above the diagonal
     for (int i = 0; i < matC.GetNrows(); ++i)
         for (int j = 0; j < i; ++j) matC(j, i) = matC(i, j);
     matC.Similarity(matV);
     // C now contiains V C^-1 V
     // Propagate corrected errors to parameters objects
     m.applyCovarianceMatrix(matC);
   }
 
   delete rw;
   delete rw2;
      }
 
      if (minos) {
   // Evaluate errs with Minos
   if (minosSet) {
     m.minos(*minosSet) ;
   } else {
     m.minos() ;
   }
      }
 
      // Optionally return fit result
      if (doSave) {
   string name = Form("fitresult_%s_%s",GetName(),data.GetName()) ;
   string title = Form("Result of fit of p.d.f. %s to dataset %s",GetName(),data.GetName()) ;
   ret = m.save(name.c_str(),title.c_str()) ;
      }
 
    }
    if (optConst) {
      m.optimizeConst(0) ;
    }
 
#endif
 
  } else {
 
    RooMinuit m(*nll) ;
 
    m.setEvalErrorWall(doEEWall) ;
    if (doWarn==0) {
      m.setNoWarn() ;
    }
 
    m.setPrintEvalErrors(numee) ;
    if (plevel!=1) {
      m.setPrintLevel(plevel) ;
    }
 
    if (optConst) {
      // Activate constant term optimization
      m.optimizeConst(optConst) ;
    }
 
    if (fitOpt) {
 
      // Play fit options as historically defined
      ret = m.fit(fitOpt) ;
 
    } else {
 
      if (verbose) {
   // Activate verbose options
   m.setVerbose(1) ;
      }
      if (doTimer) {
   // Activate timer options
   m.setProfile(1) ;
      }
 
      if (strat!=1) {
   // Modify fit strategy
   m.setStrategy(strat) ;
      }
 
      if (initHesse) {
   // Initialize errors with hesse
   m.hesse() ;
      }
 
      // Minimize using migrad
      m.migrad() ;
 
      if (hesse) {
   // Evaluate errors with Hesse
   m.hesse() ;
      }
 
      //asymptotically correct approach
      if (doAsymptotic==1 && m.getNPar()>0) {
   //Calculated corrected errors for weighted likelihood fits
   std::unique_ptr<RooFitResult> rw(m.save());
   //Weighted inverse Hessian matrix
   const TMatrixDSym& matV = rw->covarianceMatrix();
   coutI(Fitting) << "RooAbsPdf::fitTo(" << GetName() << ") Calculating covariance matrix according to the asymptotically correct approach. If you find this method useful please consider citing https://arxiv.org/abs/1911.01303." << endl;
 
   //Initialise matrix containing first derivatives
   TMatrixDSym num(rw->floatParsFinal().getSize());
   for (int k=0; k<rw->floatParsFinal().getSize(); k++)
      for (int l=0; l<rw->floatParsFinal().getSize(); l++)
         num(k,l) = 0.0;
   RooArgSet* obs = getObservables(data);
   //Create derivative objects
   std::vector<std::unique_ptr<RooDerivative> > derivatives;
   const RooArgList& floated = rw->floatParsFinal();
   std::unique_ptr<RooArgSet> floatingparams( (RooArgSet*)getParameters(data)->selectByAttrib("Constant", false) );
   for (int k=0; k<floated.getSize(); k++) {
      RooRealVar* paramresult = (RooRealVar*)floated.at(k);
      RooRealVar* paraminternal = (RooRealVar*)floatingparams->find(paramresult->getTitle());
      std::unique_ptr<RooDerivative> deriv( derivative(*paraminternal, *obs, 1) );
      derivatives.push_back(std::move(deriv));
   }
 
   //Loop over data
   for (int j=0; j<data.numEntries(); j++) {
      //Sets obs to current data point, this is where the pdf will be evaluated
      *obs = *data.get(j);
      //Determine first derivatives
      std::vector<Double_t> diffs(floated.getSize(), 0.0);
      for (int k=0; k<floated.getSize(); k++) {
         RooRealVar* paramresult = (RooRealVar*)floated.at(k);
         RooRealVar* paraminternal = (RooRealVar*)floatingparams->find(paramresult->getTitle());
         //First derivative to parameter k at best estimate point for this measurement
         Double_t diff = derivatives.at(k)->getVal();
         //Need to reset to best fit point after differentiation
         *paraminternal = paramresult->getVal();
         diffs.at(k) = diff;
      }
      //Fill numerator matrix
      Double_t prob = getVal(obs);
      for (int k=0; k<floated.getSize(); k++) {
         for (int l=0; l<floated.getSize(); l++) {
            num(k,l) += data.weight()*data.weight()*diffs.at(k)*diffs.at(l)/(prob*prob);
         }
      }
   }
   num.Similarity(matV);
 
   //Propagate corrected errors to parameters objects
   m.applyCovarianceMatrix(num);
      }
 
      if (doSumW2==1 && m.getNPar()>0) {
 
   // Make list of RooNLLVar components of FCN
   list<RooNLLVar*> nllComponents ;
   RooArgSet* comps = nll->getComponents() ;
   RooAbsArg* arg ;
   TIterator* citer = comps->createIterator() ;
   while((arg=(RooAbsArg*)citer->Next())) {
     RooNLLVar* nllComp = dynamic_cast<RooNLLVar*>(arg) ;
     if (nllComp) {
       nllComponents.push_back(nllComp) ;
     }
   }
   delete citer ;
   delete comps ;
 
   // Calculated corrected errors for weighted likelihood fits
   RooFitResult* rw = m.save() ;
   for (list<RooNLLVar*>::iterator iter1=nllComponents.begin() ; iter1!=nllComponents.end() ; ++iter1) {
     (*iter1)->applyWeightSquared(kTRUE) ;
   }
   coutI(Fitting) << "RooAbsPdf::fitTo(" << GetName() << ") Calculating sum-of-weights-squared correction matrix for covariance matrix" << endl ;
   m.hesse() ;
   RooFitResult* rw2 = m.save() ;
   for (list<RooNLLVar*>::iterator iter2=nllComponents.begin() ; iter2!=nllComponents.end() ; ++iter2) {
     (*iter2)->applyWeightSquared(kFALSE) ;
   }
 
   // Apply correction matrix
   const TMatrixDSym& matV = rw->covarianceMatrix();
   TMatrixDSym matC = rw2->covarianceMatrix();
   using ROOT::Math::CholeskyDecompGenDim;
   CholeskyDecompGenDim<Double_t> decomp(matC.GetNrows(), matC);
   if (!decomp) {
     coutE(Fitting) << "RooAbsPdf::fitTo(" << GetName()
          << ") ERROR: Cannot apply sum-of-weights correction to covariance matrix: correction matrix calculated with weight-squared is singular" <<endl ;
   } else {
     // replace C by its inverse
     decomp.Invert(matC);
     // the class lies about the matrix being symmetric, so fill in the
     // part above the diagonal
     for (int i = 0; i < matC.GetNrows(); ++i)
         for (int j = 0; j < i; ++j) matC(j, i) = matC(i, j);
     matC.Similarity(matV);
     // C now contiains V C^-1 V
     // Propagate corrected errors to parameters objects
     m.applyCovarianceMatrix(matC);
   }
 
   delete rw ;
   delete rw2 ;
      }
 
      if (minos) {
   // Evaluate errs with Minos
   if (minosSet) {
     m.minos(*minosSet) ;
   } else {
     m.minos() ;
   }
      }
 
      // Optionally return fit result
      if (doSave) {
   string name = Form("fitresult_%s_%s",GetName(),data.GetName()) ;
   string title = Form("Result of fit of p.d.f. %s to dataset %s",GetName(),data.GetName()) ;
   ret = m.save(name.c_str(),title.c_str()) ;
      }
 
    }
 
    if (optConst) {
      m.optimizeConst(0) ;
    }
 
  }
 
 
 
  // Cleanup
  delete nll ;
  return ret ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Calls RooAbsPdf::createChi2(RooDataSet& data, const RooLinkedList& cmdList) and returns fit result.
 
RooFitResult* RooAbsPdf::chi2FitTo(RooDataHist& data, const RooLinkedList& cmdList)
{
  // Select the pdf-specific commands
  RooCmdConfig pc(Form("RooAbsPdf::chi2FitTo(%s)",GetName())) ;
 
  // Pull arguments to be passed to chi2 construction from list
  RooLinkedList fitCmdList(cmdList) ;
  RooLinkedList chi2CmdList = pc.filterCmdList(fitCmdList,"Range,RangeWithName,NumCPU,Optimize,ProjectedObservables,AddCoefRange,SplitRange,DataError,Extended") ;
 
  RooAbsReal* chi2 = createChi2(data,chi2CmdList) ;
  RooFitResult* ret = chi2FitDriver(*chi2,fitCmdList) ;
 
  // Cleanup
  delete chi2 ;
  return ret ;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Create a \f$ \chi^2 \f$ from a histogram and this function.
///
/// Options to control construction of the \f$ \chi^2 \f$
/// ------------------------------------------
/// <table>
/// <tr><th> Type of CmdArg    <th>    Effect on \f$ \chi^2 \f$
/// <tr><td> `Extended()`   <td>  Use expected number of events of an extended p.d.f as normalization
/// <tr><td> `DataError()`  <td>  Choose between:
///                             - Expected error [RooAbsData::Expected]
///                             - Observed error (e.g. Sum-of-weights) [RooAbsData::SumW2]
///                             - Poisson interval [RooAbsData::Poisson]
///                             - Default: Expected error for unweighted data, Sum-of-weights for weighted data [RooAbsData::Auto]
/// <tr><td> `NumCPU()`     <td>  Activate parallel processing feature
/// <tr><td> `Range()`      <td>  Fit only selected region
/// <tr><td> `SumCoefRange()` <td>  Set the range in which to interpret the coefficients of RooAddPdf components
/// <tr><td> `SplitRange()`   <td>  Fit ranges used in different categories get named after the category.
/// Using `Range("range"), SplitRange()` as switches, different ranges could be set like this:
/// ```
/// myVariable.setRange("range_pi0", 135, 210);
/// myVariable.setRange("range_gamma", 50, 210);
/// ```
/// <tr><td> `ConditionalObservables()` <td>  Define projected observables
/// </table>
 
RooAbsReal* RooAbsPdf::createChi2(RooDataHist& data, const RooCmdArg& arg1,  const RooCmdArg& arg2,
               const RooCmdArg& arg3,  const RooCmdArg& arg4, const RooCmdArg& arg5,
               const RooCmdArg& arg6,  const RooCmdArg& arg7, const RooCmdArg& arg8)
{
  RooLinkedList cmdList ;
  cmdList.Add((TObject*)&arg1) ;  cmdList.Add((TObject*)&arg2) ;
  cmdList.Add((TObject*)&arg3) ;  cmdList.Add((TObject*)&arg4) ;
  cmdList.Add((TObject*)&arg5) ;  cmdList.Add((TObject*)&arg6) ;
  cmdList.Add((TObject*)&arg7) ;  cmdList.Add((TObject*)&arg8) ;
 
  RooCmdConfig pc(Form("RooAbsPdf::createChi2(%s)",GetName())) ;
  pc.defineString("rangeName","RangeWithName",0,"",kTRUE) ;
  pc.allowUndefined(kTRUE) ;
  pc.process(cmdList) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }
  const char* rangeName = pc.getString("rangeName",0,kTRUE) ;
 
  // Construct Chi2
  RooAbsReal::setEvalErrorLoggingMode(RooAbsReal::CollectErrors) ;
  RooAbsReal* chi2 ;
  string baseName = Form("chi2_%s_%s",GetName(),data.GetName()) ;
 
  // Clear possible range attributes from previous fits.
  setStringAttribute("fitrange", nullptr);
 
  if (!rangeName || strchr(rangeName,',')==0) {
    // Simple case: default range, or single restricted range
 
    chi2 = new RooChi2Var(baseName.c_str(),baseName.c_str(),*this,data,arg1,arg2,arg3,arg4,arg5,arg6,arg7,arg8) ;
 
  } else {
 
    // Find which argument is RangeWithName
    const RooCmdArg* rarg(0) ;
    string rcmd = "RangeWithName" ;
    if (arg1.GetName()==rcmd) rarg = &arg1 ;
    if (arg2.GetName()==rcmd) rarg = &arg2 ;
    if (arg3.GetName()==rcmd) rarg = &arg3 ;
    if (arg4.GetName()==rcmd) rarg = &arg4 ;
    if (arg5.GetName()==rcmd) rarg = &arg5 ;
    if (arg6.GetName()==rcmd) rarg = &arg6 ;
    if (arg7.GetName()==rcmd) rarg = &arg7 ;
    if (arg8.GetName()==rcmd) rarg = &arg8 ;
 
    // Composite case: multiple ranges
    RooArgList chi2List ;
    for (std::string& token : RooHelpers::tokenise(rangeName, ",")) {
      RooCmdArg subRangeCmd = RooFit::Range(token.c_str()) ;
      // Construct chi2 while substituting original RangeWithName argument with subrange argument created above
      RooAbsReal* chi2Comp = new RooChi2Var(Form("%s_%s", baseName.c_str(), token.c_str()), "chi^2", *this, data,
                   &arg1==rarg?subRangeCmd:arg1,&arg2==rarg?subRangeCmd:arg2,
                   &arg3==rarg?subRangeCmd:arg3,&arg4==rarg?subRangeCmd:arg4,
                   &arg5==rarg?subRangeCmd:arg5,&arg6==rarg?subRangeCmd:arg6,
                   &arg7==rarg?subRangeCmd:arg7,&arg8==rarg?subRangeCmd:arg8) ;
      chi2List.add(*chi2Comp) ;
    }
    chi2 = new RooAddition(baseName.c_str(),"chi^2",chi2List,kTRUE) ;
  }
  RooAbsReal::setEvalErrorLoggingMode(RooAbsReal::PrintErrors) ;
 
 
  return chi2 ;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Argument-list version of RooAbsPdf::createChi2()
 
RooAbsReal* RooAbsPdf::createChi2(RooDataSet& data, const RooLinkedList& cmdList)
{
  // Select the pdf-specific commands
  RooCmdConfig pc(Form("RooAbsPdf::createChi2(%s)",GetName())) ;
 
  pc.defineInt("integrate","Integrate",0,0) ;
  pc.defineObject("yvar","YVar",0,0) ;
 
  // Process and check varargs
  pc.process(cmdList) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }
 
  // Decode command line arguments
  Bool_t integrate = pc.getInt("integrate") ;
  RooRealVar* yvar = (RooRealVar*) pc.getObject("yvar") ;
 
  string name = Form("chi2_%s_%s",GetName(),data.GetName()) ;
 
  if (yvar) {
    return new RooXYChi2Var(name.c_str(),name.c_str(),*this,data,*yvar,integrate) ;
  } else {
    return new RooXYChi2Var(name.c_str(),name.c_str(),*this,data,integrate) ;
  }
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Print value of p.d.f, also print normalization integral that was last used, if any
 
void RooAbsPdf::printValue(ostream& os) const
{
  getVal() ;
 
  if (_norm) {
    os << evaluate() << "/" << _norm->getVal() ;
  } else {
    os << evaluate() ;
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Print multi line detailed information of this RooAbsPdf
 
void RooAbsPdf::printMultiline(ostream& os, Int_t contents, Bool_t verbose, TString indent) const
{
  RooAbsReal::printMultiline(os,contents,verbose,indent);
  os << indent << "--- RooAbsPdf ---" << endl;
  os << indent << "Cached value = " << _value << endl ;
  if (_norm) {
    os << indent << " Normalization integral: " << endl ;
    TString moreIndent(indent) ; moreIndent.Append("   ") ;
    _norm->printStream(os,kName|kAddress|kTitle|kValue|kArgs,kSingleLine,moreIndent.Data()) ;
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return a binned generator context
 
RooAbsGenContext* RooAbsPdf::binnedGenContext(const RooArgSet &vars, Bool_t verbose) const
{
  return new RooBinnedGenContext(*this,vars,0,0,verbose) ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Interface function to create a generator context from a p.d.f. This default
/// implementation returns a 'standard' context that works for any p.d.f
 
RooAbsGenContext* RooAbsPdf::genContext(const RooArgSet &vars, const RooDataSet *prototype,
               const RooArgSet* auxProto, Bool_t verbose) const
{
  return new RooGenContext(*this,vars,prototype,auxProto,verbose) ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
 
RooAbsGenContext* RooAbsPdf::autoGenContext(const RooArgSet &vars, const RooDataSet* prototype, const RooArgSet* auxProto,
                   Bool_t verbose, Bool_t autoBinned, const char* binnedTag) const
{
  if (prototype || (auxProto && auxProto->getSize()>0)) {
    return genContext(vars,prototype,auxProto,verbose);
  }
 
  RooAbsGenContext *context(0) ;
  if ( (autoBinned && isBinnedDistribution(vars)) || ( binnedTag && strlen(binnedTag) && (getAttribute(binnedTag)||string(binnedTag)=="*"))) {
    context = binnedGenContext(vars,verbose) ;
  } else {
    context= genContext(vars,0,0,verbose);
  }
  return context ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Generate a new dataset containing the specified variables with events sampled from our distribution.
/// Generate the specified number of events or expectedEvents() if not specified.
/// \param[in] whatVars Choose variables in which to generate events. Variables not listed here will remain
/// constant and not be used for event generation.
/// \param[in] argxx Optional RooCmdArg() to change behaviour of generate().
/// \return RooDataSet *, owned by caller.
///
/// Any variables of this PDF that are not in whatVars will use their
/// current values and be treated as fixed parameters. Returns zero
/// in case of an error.
///
/// <table>
/// <tr><th> Type of CmdArg                    <th> Effect on generate
/// <tr><td> `Name(const char* name)`            <td> Name of the output dataset
/// <tr><td> `Verbose(Bool_t flag)`              <td> Print informational messages during event generation
/// <tr><td> `NumEvent(int nevt)`                <td> Generate specified number of events
/// <tr><td> `Extended()`                        <td> If no number of events to be generated is given,
/// use expected number of events from extended likelihood term.
/// This evidently only works for extended PDFs.
/// <tr><td> `GenBinned(const char* tag)`        <td> Use binned generation for all component pdfs that have 'setAttribute(tag)' set
/// <tr><td> `AutoBinned(Bool_t flag)`           <td> Automatically deploy binned generation for binned distributions (e.g. RooHistPdf, sums and products of
///                                                 RooHistPdfs etc)
/// \note Datasets that are generated in binned mode are returned as weighted unbinned datasets. This means that
/// for each bin, there will be one event in the dataset with a weight corresponding to the (possibly randomised) bin content.
///
///
/// <tr><td> `AllBinned()`                       <td> As above, but for all components.
///       \note The notion of components is only meaningful for simultaneous PDFs
///       as binned generation is always executed at the top-level node for a regular
///       PDF, so for those it only mattes that the top-level node is tagged.
///
/// <tr><td> ProtoData(const RooDataSet& data, Bool_t randOrder)
///          <td> Use specified dataset as prototype dataset. If randOrder in ProtoData() is set to true,
///               the order of the events in the dataset will be read in a random order if the requested
///               number of events to be generated does not match the number of events in the prototype dataset.
///               \note If ProtoData() is used, the specified existing dataset as a prototype: the new dataset will contain
///               the same number of events as the prototype (unless otherwise specified), and any prototype variables not in
///               whatVars will be copied into the new dataset for each generated event and also used to set our PDF parameters.
///               The user can specify a  number of events to generate that will override the default. The result is a
///               copy of the prototype dataset with only variables in whatVars randomized. Variables in whatVars that
///               are not in the prototype will be added as new columns to the generated dataset.
///
/// </table>
///
/// #### Accessing the underlying event generator
/// Depending on the fit model (if it is difficult to sample), it may be necessary to change generator settings.
/// For the default generator (RooFoamGenerator), the number of samples or cells could be increased by e.g. using
///     myPdf->specialGeneratorConfig()->getConfigSection("RooFoamGenerator").setRealValue("nSample",1e4);
///
/// The foam generator e.g. has the following config options:
/// - nCell[123N]D
/// - nSample
/// - chatLevel
/// \see rf902_numgenconfig.C
 
RooDataSet *RooAbsPdf::generate(const RooArgSet& whatVars, const RooCmdArg& arg1,const RooCmdArg& arg2,
            const RooCmdArg& arg3,const RooCmdArg& arg4, const RooCmdArg& arg5,const RooCmdArg& arg6)
{
  // Select the pdf-specific commands
  RooCmdConfig pc(Form("RooAbsPdf::generate(%s)",GetName())) ;
  pc.defineObject("proto","PrototypeData",0,0) ;
  pc.defineString("dsetName","Name",0,"") ;
  pc.defineInt("randProto","PrototypeData",0,0) ;
  pc.defineInt("resampleProto","PrototypeData",1,0) ;
  pc.defineInt("verbose","Verbose",0,0) ;
  pc.defineInt("extended","Extended",0,0) ;
  pc.defineInt("nEvents","NumEvents",0,0) ;
  pc.defineInt("autoBinned","AutoBinned",0,1) ;
  pc.defineInt("expectedData","ExpectedData",0,0) ;
  pc.defineDouble("nEventsD","NumEventsD",0,-1.) ;
  pc.defineString("binnedTag","GenBinned",0,"") ;
  pc.defineMutex("GenBinned","ProtoData") ;
  pc.defineMutex("Extended", "NumEvents");
 
  // Process and check varargs
  pc.process(arg1,arg2,arg3,arg4,arg5,arg6) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }
 
  // Decode command line arguments
  RooDataSet* protoData = static_cast<RooDataSet*>(pc.getObject("proto",0)) ;
  const char* dsetName = pc.getString("dsetName") ;
  Bool_t verbose = pc.getInt("verbose") ;
  Bool_t randProto = pc.getInt("randProto") ;
  Bool_t resampleProto = pc.getInt("resampleProto") ;
  Bool_t extended = pc.getInt("extended") ;
  Bool_t autoBinned = pc.getInt("autoBinned") ;
  const char* binnedTag = pc.getString("binnedTag") ;
  Int_t nEventsI = pc.getInt("nEvents") ;
  Double_t nEventsD = pc.getInt("nEventsD") ;
  //Bool_t verbose = pc.getInt("verbose") ;
  Bool_t expectedData = pc.getInt("expectedData") ;
 
  Double_t nEvents = (nEventsD>0) ? nEventsD : Double_t(nEventsI);
 
  // Force binned mode for expected data mode
  if (expectedData) {
    binnedTag="*" ;
  }
 
  if (extended) {
     if (nEvents == 0) nEvents = expectedEvents(&whatVars);
  } else if (nEvents==0) {
    cxcoutI(Generation) << "No number of events specified , number of events generated is "
           << GetName() << "::expectedEvents() = " << expectedEvents(&whatVars)<< endl ;
  }
 
  if (extended && protoData && !randProto) {
    cxcoutI(Generation) << "WARNING Using generator option Extended() (Poisson distribution of #events) together "
           << "with a prototype dataset implies incomplete sampling or oversampling of proto data. "
           << "Set randomize flag in ProtoData() option to randomize prototype dataset order and thus "
           << "to randomize the set of over/undersampled prototype events for each generation cycle." << endl ;
  }
 
 
  // Forward to appropriate implementation
  RooDataSet* data ;
  if (protoData) {
    data = generate(whatVars,*protoData,Int_t(nEvents),verbose,randProto,resampleProto) ;
  } else {
     data = generate(whatVars,nEvents,verbose,autoBinned,binnedTag,expectedData, extended) ;
  }
 
  // Rename dataset to given name if supplied
  if (dsetName && strlen(dsetName)>0) {
    data->SetName(dsetName) ;
  }
 
  return data ;
}
 
 
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// \note This method does not perform any generation. To generate according to generations specification call RooAbsPdf::generate(RooAbsPdf::GenSpec&) const
///
/// Details copied from RooAbsPdf::generate():
/// --------------------------------------------
/// \copydetails RooAbsPdf::generate(const RooArgSet&,const RooCmdArg&,const RooCmdArg&,const RooCmdArg&,const RooCmdArg&,const RooCmdArg&,const RooCmdArg&)
 
RooAbsPdf::GenSpec* RooAbsPdf::prepareMultiGen(const RooArgSet &whatVars,
                      const RooCmdArg& arg1,const RooCmdArg& arg2,
                      const RooCmdArg& arg3,const RooCmdArg& arg4,
                      const RooCmdArg& arg5,const RooCmdArg& arg6)
{
 
  // Select the pdf-specific commands
  RooCmdConfig pc(Form("RooAbsPdf::generate(%s)",GetName())) ;
  pc.defineObject("proto","PrototypeData",0,0) ;
  pc.defineString("dsetName","Name",0,"") ;
  pc.defineInt("randProto","PrototypeData",0,0) ;
  pc.defineInt("resampleProto","PrototypeData",1,0) ;
  pc.defineInt("verbose","Verbose",0,0) ;
  pc.defineInt("extended","Extended",0,0) ;
  pc.defineInt("nEvents","NumEvents",0,0) ;
  pc.defineInt("autoBinned","AutoBinned",0,1) ;
  pc.defineString("binnedTag","GenBinned",0,"") ;
  pc.defineMutex("GenBinned","ProtoData") ;
 
 
  // Process and check varargs
  pc.process(arg1,arg2,arg3,arg4,arg5,arg6) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }
 
  // Decode command line arguments
  RooDataSet* protoData = static_cast<RooDataSet*>(pc.getObject("proto",0)) ;
  const char* dsetName = pc.getString("dsetName") ;
  Int_t nEvents = pc.getInt("nEvents") ;
  Bool_t verbose = pc.getInt("verbose") ;
  Bool_t randProto = pc.getInt("randProto") ;
  Bool_t resampleProto = pc.getInt("resampleProto") ;
  Bool_t extended = pc.getInt("extended") ;
  Bool_t autoBinned = pc.getInt("autoBinned") ;
  const char* binnedTag = pc.getString("binnedTag") ;
 
  RooAbsGenContext* cx = autoGenContext(whatVars,protoData,0,verbose,autoBinned,binnedTag) ;
 
  return new GenSpec(cx,whatVars,protoData,nEvents,extended,randProto,resampleProto,dsetName) ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// If many identical generation requests
/// are needed, e.g. in toy MC studies, it is more efficient to use the prepareMultiGen()/generate()
/// combination than calling the standard generate() multiple times as
/// initialization overhead is only incurred once.
 
RooDataSet *RooAbsPdf::generate(RooAbsPdf::GenSpec& spec) const
{
  //Int_t nEvt = spec._extended ? RooRandom::randomGenerator()->Poisson(spec._nGen) : spec._nGen ;
  //Int_t nEvt = spec._extended ? RooRandom::randomGenerator()->Poisson(spec._nGen==0?expectedEvents(spec._whatVars):spec._nGen) : spec._nGen ;
  //Int_t nEvt = spec._nGen == 0 ? RooRandom::randomGenerator()->Poisson(expectedEvents(spec._whatVars)) : spec._nGen;
 
  Double_t nEvt =  spec._nGen == 0 ?  expectedEvents(spec._whatVars) : spec._nGen;
 
  RooDataSet* ret = generate(*spec._genContext,spec._whatVars,spec._protoData, nEvt,kFALSE,spec._randProto,spec._resampleProto,
              spec._init,spec._extended) ;
  spec._init = kTRUE ;
  return ret ;
}
 
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Generate a new dataset containing the specified variables with
/// events sampled from our distribution.
///
/// \param[in] whatVars Generate a dataset with the variables (and categories) in this set.
/// Any variables of this PDF that are not in `whatVars` will use their
/// current values and be treated as fixed parameters.
/// \param[in] nEvents Generate the specified number of events or else try to use
/// expectedEvents() if nEvents <= 0 (default).
/// \param[in] verbose Show which generator strategies are being used.
/// \param[in] autoBinned If original distribution is binned, return bin centers and randomise weights
/// instead of generating single events.
/// \param[in] binnedTag
/// \param[in] expectedData Call setExpectedData on the genContext.
/// \param[in] extended Randomise number of events generated according to Poisson(nEvents). Only useful
/// if PDF is extended.
/// \return New dataset. Returns zero in case of an error. The caller takes ownership of the returned
/// dataset.
 
RooDataSet *RooAbsPdf::generate(const RooArgSet &whatVars, Double_t nEvents, Bool_t verbose, Bool_t autoBinned, const char* binnedTag, Bool_t expectedData, Bool_t extended) const
{
  if (nEvents==0 && extendMode()==CanNotBeExtended) {
    return new RooDataSet("emptyData","emptyData",whatVars) ;
  }
 
  // Request for binned generation
  RooAbsGenContext *context = autoGenContext(whatVars,0,0,verbose,autoBinned,binnedTag) ;
  if (expectedData) {
    context->setExpectedData(kTRUE) ;
  }
 
  RooDataSet *generated = 0;
  if(0 != context && context->isValid()) {
     generated= context->generate(nEvents, kFALSE, extended);
  }
  else {
    coutE(Generation)  << "RooAbsPdf::generate(" << GetName() << ") cannot create a valid context" << endl;
  }
  if(0 != context) delete context;
  return generated;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Internal method
 
RooDataSet *RooAbsPdf::generate(RooAbsGenContext& context, const RooArgSet &whatVars, const RooDataSet *prototype,
            Double_t nEvents, Bool_t /*verbose*/, Bool_t randProtoOrder, Bool_t resampleProto,
            Bool_t skipInit, Bool_t extended) const
{
  if (nEvents==0 && (prototype==0 || prototype->numEntries()==0)) {
    return new RooDataSet("emptyData","emptyData",whatVars) ;
  }
 
  RooDataSet *generated = 0;
 
  // Resampling implies reshuffling in the implementation
  if (resampleProto) {
    randProtoOrder=kTRUE ;
  }
 
  if (randProtoOrder && prototype && prototype->numEntries()!=nEvents) {
    coutI(Generation) << "RooAbsPdf::generate (Re)randomizing event order in prototype dataset (Nevt=" << nEvents << ")" << endl ;
    Int_t* newOrder = randomizeProtoOrder(prototype->numEntries(),Int_t(nEvents),resampleProto) ;
    context.setProtoDataOrder(newOrder) ;
    delete[] newOrder ;
  }
 
  if(context.isValid()) {
    generated= context.generate(nEvents,skipInit,extended);
  }
  else {
    coutE(Generation) << "RooAbsPdf::generate(" << GetName() << ") do not have a valid generator context" << endl;
  }
  return generated;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Generate a new dataset using a prototype dataset as a model,
/// with values of the variables in `whatVars` sampled from our distribution.
///
/// \param[in] whatVars Generate for these variables.
/// \param[in] prototype Use this dataset
/// as a prototype: the new dataset will contain the same number of
/// events as the prototype (by default), and any prototype variables not in
/// whatVars will be copied into the new dataset for each generated
/// event and also used to set our PDF parameters. The user can specify a
/// number of events to generate that will override the default. The result is a
/// copy of the prototype dataset with only variables in whatVars
/// randomized. Variables in whatVars that are not in the prototype
/// will be added as new columns to the generated dataset.
/// \param[in] nEvents Number of events to generate. Defaults to 0, which means number
/// of event in prototype dataset.
/// \param[in] verbose Show which generator strategies are being used.
/// \param[in] randProtoOrder Randomise order of retrieval of events from proto dataset.
/// \param[in] resampleProto Resample from the proto dataset.
/// \return The new dataset. Returns zero in case of an error. The caller takes ownership of the
/// returned dataset.
 
RooDataSet *RooAbsPdf::generate(const RooArgSet &whatVars, const RooDataSet& prototype,
            Int_t nEvents, Bool_t verbose, Bool_t randProtoOrder, Bool_t resampleProto) const
{
  RooAbsGenContext *context= genContext(whatVars,&prototype,0,verbose);
  if (context) {
    RooDataSet* data =  generate(*context,whatVars,&prototype,nEvents,verbose,randProtoOrder,resampleProto) ;
    delete context ;
    return data ;
  } else {
    coutE(Generation) << "RooAbsPdf::generate(" << GetName() << ") ERROR creating generator context" << endl ;
    return 0 ;
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return lookup table with randomized access order for prototype events,
/// given nProto prototype data events and nGen events that will actually
/// be accessed
 
Int_t* RooAbsPdf::randomizeProtoOrder(Int_t nProto, Int_t, Bool_t resampleProto) const
{
  // Make unsorted linked list of indeces
  RooLinkedList l ;
  Int_t i ;
  for (i=0 ; i<nProto ; i++) {
    l.Add(new RooInt(i)) ;
  }
 
  // Make output list
  Int_t* lut = new Int_t[nProto] ;
 
  // Randomly samply input list into output list
  if (!resampleProto) {
    // In this mode, randomization is a strict reshuffle of the order
    for (i=0 ; i<nProto ; i++) {
      Int_t iran = RooRandom::integer(nProto-i) ;
      RooInt* sample = (RooInt*) l.At(iran) ;
      lut[i] = *sample ;
      l.Remove(sample) ;
      delete sample ;
    }
  } else {
    // In this mode, we resample, i.e. events can be used more than once
    for (i=0 ; i<nProto ; i++) {
      lut[i] = RooRandom::integer(nProto);
    }
  }
 
 
  return lut ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Load generatedVars with the subset of directVars that we can generate events for,
/// and return a code that specifies the generator algorithm we will use. A code of
/// zero indicates that we cannot generate any of the directVars (in this case, nothing
/// should be added to generatedVars). Any non-zero codes will be passed to our generateEvent()
/// implementation, but otherwise its value is arbitrary. The default implemetation of
/// this method returns zero. Subclasses will usually implement this method using the
/// matchArgs() methods to advertise the algorithms they provide.
 
Int_t RooAbsPdf::getGenerator(const RooArgSet &/*directVars*/, RooArgSet &/*generatedVars*/, Bool_t /*staticInitOK*/) const
{
  return 0 ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Interface for one-time initialization to setup the generator for the specified code.
 
void RooAbsPdf::initGenerator(Int_t /*code*/)
{
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Interface for generation of an event using the algorithm
/// corresponding to the specified code. The meaning of each code is
/// defined by the getGenerator() implementation. The default
/// implementation does nothing.
 
void RooAbsPdf::generateEvent(Int_t /*code*/)
{
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Check if given observable can be safely generated using the
/// pdfs internal generator mechanism (if that existsP). Observables
/// on which a PDF depends via more than route are not safe
/// for use with internal generators because they introduce
/// correlations not known to the internal generator
 
Bool_t RooAbsPdf::isDirectGenSafe(const RooAbsArg& arg) const
{
  // Arg must be direct server of self
  if (!findServer(arg.GetName())) return kFALSE ;
 
  // There must be no other dependency routes
  for (const auto server : _serverList) {
    if(server == &arg) continue;
    if(server->dependsOn(arg)) {
      return kFALSE ;
    }
  }
 
  return kTRUE ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Generate a new dataset containing the specified variables with events sampled from our distribution.
/// \param[in] whatVars Choose variables in which to generate events. Variables not listed here will remain
/// constant and not be used for event generation
/// \param[in] arg1 Optional RooCmdArg to change behaviour of generateBinned()
/// \return RooDataHist *, to be managed by caller.
///
/// Generate the specified number of events or expectedEvents() if not specified.
///
/// Any variables of this PDF that are not in whatVars will use their
/// current values and be treated as fixed parameters. Returns zero
/// in case of an error. The caller takes ownership of the returned
/// dataset.
///
/// The following named arguments are supported
/// | Type of CmdArg       | Effect on generation
/// |-------------------------|-----------------------
/// | `Name(const char* name)`  | Name of the output dataset
/// | `Verbose(Bool_t flag)`    | Print informational messages during event generation
/// | `NumEvent(int nevt)`      | Generate specified number of events
/// | `Extended()`              | The actual number of events generated will be sampled from a Poisson distribution with mu=nevt. For use with extended maximum likelihood fits
/// | `ExpectedData()`          | Return a binned dataset _without_ statistical fluctuations (also aliased as Asimov())
///
 
RooDataHist *RooAbsPdf::generateBinned(const RooArgSet& whatVars, const RooCmdArg& arg1,const RooCmdArg& arg2,
                   const RooCmdArg& arg3,const RooCmdArg& arg4, const RooCmdArg& arg5,const RooCmdArg& arg6) const
{
 
  // Select the pdf-specific commands
  RooCmdConfig pc(Form("RooAbsPdf::generate(%s)",GetName())) ;
  pc.defineString("dsetName","Name",0,"") ;
  pc.defineInt("verbose","Verbose",0,0) ;
  pc.defineInt("extended","Extended",0,0) ;
  pc.defineInt("nEvents","NumEvents",0,0) ;
  pc.defineDouble("nEventsD","NumEventsD",0,-1.) ;
  pc.defineInt("expectedData","ExpectedData",0,0) ;
 
  // Process and check varargs
  pc.process(arg1,arg2,arg3,arg4,arg5,arg6) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }
 
  // Decode command line arguments
  Double_t nEvents = pc.getDouble("nEventsD") ;
  if (nEvents<0) {
    nEvents = pc.getInt("nEvents") ;
  }
  //Bool_t verbose = pc.getInt("verbose") ;
  Bool_t extended = pc.getInt("extended") ;
  Bool_t expectedData = pc.getInt("expectedData") ;
  const char* dsetName = pc.getString("dsetName") ;
 
  if (extended) {
     //nEvents = (nEvents==0?Int_t(expectedEvents(&whatVars)+0.5):nEvents) ;
    nEvents = (nEvents==0 ? expectedEvents(&whatVars) :nEvents) ;
    cxcoutI(Generation) << " Extended mode active, number of events generated (" << nEvents << ") is Poisson fluctuation on "
         << GetName() << "::expectedEvents() = " << nEvents << endl ;
    // If Poisson fluctuation results in zero events, stop here
    if (nEvents==0) {
      return 0 ;
    }
  } else if (nEvents==0) {
    cxcoutI(Generation) << "No number of events specified , number of events generated is "
         << GetName() << "::expectedEvents() = " << expectedEvents(&whatVars)<< endl ;
  }
 
  // Forward to appropriate implementation
  RooDataHist* data = generateBinned(whatVars,nEvents,expectedData,extended) ;
 
  // Rename dataset to given name if supplied
  if (dsetName && strlen(dsetName)>0) {
    data->SetName(dsetName) ;
  }
 
  return data ;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Generate a new dataset containing the specified variables with
/// events sampled from our distribution. Generate the specified
/// number of events or else try to use expectedEvents() if nEvents <= 0.
///
/// If expectedData is kTRUE (it is kFALSE by default), the returned histogram returns the 'expected'
/// data sample, i.e. no statistical fluctuations are present.
///
/// Any variables of this PDF that are not in whatVars will use their
/// current values and be treated as fixed parameters. Returns zero
/// in case of an error. The caller takes ownership of the returned
/// dataset.
 
RooDataHist *RooAbsPdf::generateBinned(const RooArgSet &whatVars, Double_t nEvents, Bool_t expectedData, Bool_t extended) const
{
  // Create empty RooDataHist
  RooDataHist* hist = new RooDataHist("genData","genData",whatVars) ;
 
  // Scale to number of events and introduce Poisson fluctuations
  if (nEvents<=0) {
    if (!canBeExtended()) {
      coutE(InputArguments) << "RooAbsPdf::generateBinned(" << GetName() << ") ERROR: No event count provided and p.d.f does not provide expected number of events" << endl ;
      delete hist ;
      return 0 ;
    } else {
 
      // Don't round in expectedData or extended mode
      if (expectedData || extended) {
   nEvents = expectedEvents(&whatVars) ;
      } else {
   nEvents = Int_t(expectedEvents(&whatVars)+0.5) ;
      }
    }
  }
 
  // Sample p.d.f. distribution
  fillDataHist(hist,&whatVars,1,kTRUE) ;
 
  vector<int> histOut(hist->numEntries()) ;
  Double_t histMax(-1) ;
  Int_t histOutSum(0) ;
  for (int i=0 ; i<hist->numEntries() ; i++) {
    hist->get(i) ;
    if (expectedData) {
 
      // Expected data, multiply p.d.f by nEvents
      Double_t w=hist->weight()*nEvents ;
      hist->set(w,sqrt(w)) ;
 
    } else if (extended) {
 
      // Extended mode, set contents to Poisson(pdf*nEvents)
      Double_t w = RooRandom::randomGenerator()->Poisson(hist->weight()*nEvents) ;
      hist->set(w,sqrt(w)) ;
 
    } else {
 
      // Regular mode, fill array of weights with Poisson(pdf*nEvents), but to not fill
      // histogram yet.
      if (hist->weight()>histMax) {
   histMax = hist->weight() ;
      }
      histOut[i] = RooRandom::randomGenerator()->Poisson(hist->weight()*nEvents) ;
      histOutSum += histOut[i] ;
    }
  }
 
 
  if (!expectedData && !extended) {
 
    // Second pass for regular mode - Trim/Extend dataset to exact number of entries
 
    // Calculate difference between what is generated so far and what is requested
    Int_t nEvtExtra = abs(Int_t(nEvents)-histOutSum) ;
    Int_t wgt = (histOutSum>nEvents) ? -1 : 1 ;
 
    // Perform simple binned accept/reject procedure to get to exact event count
    while(nEvtExtra>0) {
 
      Int_t ibinRand = RooRandom::randomGenerator()->Integer(hist->numEntries()) ;
      hist->get(ibinRand) ;
      Double_t ranY = RooRandom::randomGenerator()->Uniform(histMax) ;
 
      if (ranY<hist->weight()) {
   if (wgt==1) {
     histOut[ibinRand]++ ;
   } else {
     // If weight is negative, prior bin content must be at least 1
     if (histOut[ibinRand]>0) {
       histOut[ibinRand]-- ;
     } else {
       continue ;
     }
   }
   nEvtExtra-- ;
      }
    }
 
    // Transfer working array to histogram
    for (int i=0 ; i<hist->numEntries() ; i++) {
      hist->get(i) ;
      hist->set(histOut[i],sqrt(1.0*histOut[i])) ;
    }
 
  } else if (expectedData) {
 
    // Second pass for expectedData mode -- Normalize to exact number of requested events
    // Minor difference may be present in first round due to difference between
    // bin average and bin integral in sampling bins
    Double_t corr = nEvents/hist->sumEntries() ;
    for (int i=0 ; i<hist->numEntries() ; i++) {
      hist->get(i) ;
      hist->set(hist->weight()*corr,sqrt(hist->weight()*corr)) ;
    }
 
  }
 
  return hist;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Special generator interface for generation of 'global observables' -- for RooStats tools
 
RooDataSet* RooAbsPdf::generateSimGlobal(const RooArgSet& whatVars, Int_t nEvents)
{
  return generate(whatVars,nEvents) ;
}
 
namespace {
void removeRangeOverlap(std::vector<std::pair<double, double>>& ranges) {
  //Sort from left to right
  std::sort(ranges.begin(), ranges.end());
 
  for (auto it = ranges.begin(); it != ranges.end(); ++it) {
    double& startL = it->first;
    double& endL   = it->second;
 
    for (auto innerIt = it+1; innerIt != ranges.end(); ++innerIt) {
      const double startR = innerIt->first;
      const double endR   = innerIt->second;
 
      if (startL <= startR && startR <= endL) {
        //Overlapping ranges, extend left one
        endL = std::max(endL, endR);
        *innerIt = make_pair(0., 0.);
      }
    }
  }
 
  auto newEnd = std::remove_if(ranges.begin(), ranges.end(),
      [](const std::pair<double,double>& input){
          return input.first == input.second;
      });
  ranges.erase(newEnd, ranges.end());
}
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Plot (project) PDF on specified frame.
/// - If a PDF is plotted in an empty frame, it
/// will show a unit-normalized curve in the frame variable. When projecting a multi-
/// dimensional PDF onto the frame axis, hidden parameters are taken are taken at
/// their current value.
/// - If a PDF is plotted in a frame in which a dataset has already been plotted, it will
/// show a projection integrated over all variables that were present in the shown
/// dataset (except for the one on the x-axis). The normalization of the curve will
/// be adjusted to the event count of the plotted dataset. An informational message
/// will be printed for each projection step that is performed.
/// - If a PDF is plotted in a frame showing a dataset *after* a fit, the above happens,
/// but the PDF will be drawn and normalised only in the fit range. If this is not desired,
/// plotting and normalisation range can be overridden using Range() and NormRange() as
/// documented in the table below.
///
/// This function takes the following named arguments (for more arguments, see also
/// RooAbsReal::plotOn(RooPlot*,const RooCmdArg&,const RooCmdArg&,const RooCmdArg&,const RooCmdArg&,
/// const RooCmdArg&,const RooCmdArg&,const RooCmdArg&,const RooCmdArg&,const RooCmdArg&,
/// const RooCmdArg&) const )
///
///
/// <table>
/// <tr><th> Type of argument <th> Controlling normalisation
/// <tr><td> `NormRange(const char* name)`      <td>  Calculate curve normalization w.r.t. specified range[s].
///               See the tutorial rf212_plottingInRanges_blinding.C
///               \note Setting a Range() by default also sets a NormRange() on the same range, meaning that the
///               PDF is plotted and normalised in the same range. Overriding this can be useful if the PDF was fit
///               in limited range[s] such as side bands, `NormRange("sidebandLeft,sidebandRight")`, but the PDF
///               should be drawn in the full range, `Range("")`.
///
/// <tr><td> `Normalization(Double_t scale, ScaleType code)`   <td>  Adjust normalization by given scale factor.
///               Interpretation of number depends on code:
///                 `RooAbsReal::Relative`: relative adjustment factor
///                 `RooAbsReal::NumEvent`: scale to match given number of events.
///
/// <tr><th> Type of argument <th> Misc control
/// <tr><td> `Name(const chat* name)`           <td>  Give curve specified name in frame. Useful if curve is to be referenced later
/// <tr><td> `Asymmetry(const RooCategory& c)`  <td>  Show the asymmetry of the PDF in given two-state category
///               \f$ \frac{F(+)-F(-)}{F(+)+F(-)} \f$ rather than the PDF projection. Category must have two
///               states with indices -1 and +1 or three states with indeces -1,0 and +1.
/// <tr><td> `ShiftToZero(Bool_t flag)`         <td>  Shift entire curve such that lowest visible point is at exactly zero.
///               Mostly useful when plotting -log(L) or \f$ \chi^2 \f$ distributions
/// <tr><td> `AddTo(const char* name, double_t wgtSelf, double_t wgtOther)`  <td>  Create a projection of this PDF onto the x-axis, but
///               instead of plotting it directly, add it to an existing curve with given name (and relative weight factors).
/// <tr><td> `Components(const char* names)`  <td>  When plotting sums of PDFs, plot only the named components (*e.g.* only
///                                                 the signal of a signal+background model).
/// <tr><td> `Components(const RooArgSet& compSet)` <td> As above, but pass a RooArgSet of the components themselves.
///
/// <tr><th> Type of argument                 <th> Projection control
/// <tr><td> `Slice(const RooArgSet& set)`     <td> Override default projection behaviour by omitting observables listed
///                                    in set from the projection, i.e. by not integrating over these.
///                                    Slicing is usually only sensible in discrete observables, by e.g. creating a slice
///                                    of the PDF at the current value of the category observable.
/// <tr><td> `Slice(RooCategory& cat, const char* label)`        <td> Override default projection behaviour by omitting the specified category
///                                    observable from the projection, i.e., by not integrating over all states of this category.
///                                    The slice is positioned at the given label value. Multiple Slice() commands can be given to specify slices
///                                    in multiple observables, e.g.
/// ```{.cpp}
///   pdf.plotOn(frame, Slice(tagCategory, "2tag"), Slice(jetCategory, "3jet"));
/// ```
/// <tr><td> `Project(const RooArgSet& set)`    <td>  Override default projection behaviour by projecting
///               over observables given in set, completely ignoring the default projection behavior. Advanced use only.
/// <tr><td> `ProjWData(const RooAbsData& d)`   <td>  Override default projection _technique_ (integration). For observables
///               present in given dataset projection of PDF is achieved by constructing an average over all observable
///               values in given set. Consult RooFit plotting tutorial for further explanation of meaning & use of this technique
/// <tr><td> `ProjWData(const RooArgSet& s, const RooAbsData& d)`   <td>  As above but only consider subset 's' of
///               observables in dataset 'd' for projection through data averaging
/// <tr><td> `ProjectionRange(const char* rn)`  <td>  When projecting the PDF onto the plot axis, it is usually integrated
///               over the full range of the invisible variables. The ProjectionRange overrides this.
///               This is useful if the PDF was fitted in a limited range in y, but it is now projected onto x. If
///               `ProjectionRange("<name of fit range>")` is passed, the projection is normalised correctly.
///
/// <tr><th> Type of argument <th> Plotting control
/// <tr><td> `LineStyle(Int_t style)`           <td>  Select line style by ROOT line style code, default is solid
/// <tr><td> `LineColor(Int_t color)`           <td>  Select line color by ROOT color code, default is blue
/// <tr><td> `LineWidth(Int_t width)`           <td>  Select line with in pixels, default is 3
/// <tr><td> `FillStyle(Int_t style)`           <td>  Select fill style, default is not filled. If a filled style is selected,
///                                                 also use VLines() to add vertical downward lines at end of curve to ensure proper closure
/// <tr><td> `FillColor(Int_t color)`           <td>  Select fill color by ROOT color code
/// <tr><td> `Range(const char* name)`          <td>  Only draw curve in range defined by given name. Multiple comma-separated ranges can be given.
///                                                   An empty string "" or `nullptr` means to use the default range of the variable.
/// <tr><td> `Range(double lo, double hi)`      <td>  Only draw curve in specified range
/// <tr><td> `VLines()`                         <td>  Add vertical lines to y=0 at end points of curve
/// <tr><td> `Precision(Double_t eps)`          <td>  Control precision of drawn curve w.r.t to scale of plot, default is 1e-3. A higher precision will
///    result in more and more densely spaced curve points. A negative precision value will disable
///    adaptive point spacing and restrict sampling to the grid point of points defined by the binning
///    of the plotted observable (recommended for expensive functions such as profile likelihoods)
/// <tr><td> `Invisible(Bool_t flag)`           <td>  Add curve to frame, but do not display. Useful in combination AddTo()
/// <tr><td> `VisualizeError(const RooFitResult& fitres, Double_t Z=1, Bool_t linearMethod=kTRUE)`
///                                  <td> Visualize the uncertainty on the parameters, as given in fitres, at 'Z' sigma.
///
/// <tr><td> `VisualizeError(const RooFitResult& fitres, const RooArgSet& param, Double_t Z=1, Bool_t linearMethod=kTRUE)`
///                                  <td> Visualize the uncertainty on the subset of parameters 'param', as given in fitres, at 'Z' sigma.
/// </table>
 
RooPlot* RooAbsPdf::plotOn(RooPlot* frame, RooLinkedList& cmdList) const
{
 
  // Pre-processing if p.d.f. contains a fit range and there is no command specifying one,
  // add a fit range as default range
  RooCmdArg* plotRange(0) ;
  RooCmdArg* normRange2(0);
  if (getStringAttribute("fitrange") && !cmdList.FindObject("Range") &&
      !cmdList.FindObject("RangeWithName")) {
    plotRange = (RooCmdArg*) RooFit::Range(getStringAttribute("fitrange")).Clone() ;
    cmdList.Add(plotRange) ;
  }
 
  if (getStringAttribute("fitrange") && !cmdList.FindObject("NormRange")) {
    normRange2 = (RooCmdArg*) RooFit::NormRange(getStringAttribute("fitrange")).Clone() ;
    cmdList.Add(normRange2) ;
  }
 
  if (plotRange || normRange2) {
    coutI(Plotting) << "RooAbsPdf::plotOn(" << GetName() << ") p.d.f was fitted in a subrange and no explicit "
          << (plotRange?"Range()":"") << ((plotRange&&normRange2)?" and ":"")
          << (normRange2?"NormRange()":"") << " was specified. Plotting / normalising in fit range. To override, do one of the following"
          << "\n\t- Clear the automatic fit range attribute: <pdf>.setStringAttribute(\"fitrange\", nullptr);"
          << "\n\t- Explicitly specify the plotting range: Range(\"<rangeName>\")."
          << "\n\t- Explicitly specify where to compute the normalisation: NormRange(\"<rangeName>\")."
          << "\n\tThe default (full) range can be denoted with Range(\"\") / NormRange(\"\")."<< endl ;
  }
 
  // Sanity checks
  if (plotSanityChecks(frame)) return frame ;
 
  // Select the pdf-specific commands
  RooCmdConfig pc(Form("RooAbsPdf::plotOn(%s)",GetName())) ;
  pc.defineDouble("scaleFactor","Normalization",0,1.0) ;
  pc.defineInt("scaleType","Normalization",0,Relative) ;
  pc.defineObject("compSet","SelectCompSet",0) ;
  pc.defineString("compSpec","SelectCompSpec",0) ;
  pc.defineObject("asymCat","Asymmetry",0) ;
  pc.defineDouble("rangeLo","Range",0,-999.) ;
  pc.defineDouble("rangeHi","Range",1,-999.) ;
  pc.defineString("rangeName","RangeWithName",0,"") ;
  pc.defineString("normRangeName","NormRange",0,"") ;
  pc.defineInt("rangeAdjustNorm","Range",0,0) ;
  pc.defineInt("rangeWNAdjustNorm","RangeWithName",0,0) ;
  pc.defineMutex("SelectCompSet","SelectCompSpec") ;
  pc.defineMutex("Range","RangeWithName") ;
  pc.allowUndefined() ; // unknowns may be handled by RooAbsReal
 
  // Process and check varargs
  pc.process(cmdList) ;
  if (!pc.ok(kTRUE)) {
    return frame ;
  }
 
  // Decode command line arguments
  ScaleType stype = (ScaleType) pc.getInt("scaleType") ;
  Double_t scaleFactor = pc.getDouble("scaleFactor") ;
  const RooAbsCategoryLValue* asymCat = (const RooAbsCategoryLValue*) pc.getObject("asymCat") ;
  const char* compSpec = pc.getString("compSpec") ;
  const RooArgSet* compSet = (const RooArgSet*) pc.getObject("compSet") ;
  Bool_t haveCompSel = ( (compSpec && strlen(compSpec)>0) || compSet) ;
 
  // Suffix for curve name
  TString nameSuffix ;
  if (compSpec && strlen(compSpec)>0) {
    nameSuffix.Append("_Comp[") ;
    nameSuffix.Append(compSpec) ;
    nameSuffix.Append("]") ;
  } else if (compSet) {
    nameSuffix.Append("_Comp[") ;
    nameSuffix.Append(compSet->contentsString().c_str()) ;
    nameSuffix.Append("]") ;
  }
 
  // Remove PDF-only commands from command list
  pc.stripCmdList(cmdList,"SelectCompSet,SelectCompSpec") ;
 
  // Adjust normalization, if so requested
  if (asymCat) {
    RooCmdArg cnsuffix("CurveNameSuffix",0,0,0,0,nameSuffix.Data(),0,0,0) ;
    cmdList.Add(&cnsuffix);
    return  RooAbsReal::plotOn(frame,cmdList) ;
  }
 
  // More sanity checks
  Double_t nExpected(1) ;
  if (stype==RelativeExpected) {
    if (!canBeExtended()) {
      coutE(Plotting) << "RooAbsPdf::plotOn(" << GetName()
            << "): ERROR the 'Expected' scale option can only be used on extendable PDFs" << endl ;
      return frame ;
    }
    nExpected = expectedEvents(frame->getNormVars()) ;
  }
 
  if (stype != Raw) {
 
    if (frame->getFitRangeNEvt() && stype==Relative) {
 
      Bool_t hasCustomRange(kFALSE), adjustNorm(kFALSE) ;
 
      std::vector<pair<Double_t,Double_t> > rangeLim;
 
      // Retrieve plot range to be able to adjust normalization to data
      if (pc.hasProcessed("Range")) {
 
        Double_t rangeLo = pc.getDouble("rangeLo") ;
        Double_t rangeHi = pc.getDouble("rangeHi") ;
        rangeLim.push_back(make_pair(rangeLo,rangeHi)) ;
        adjustNorm = pc.getInt("rangeAdjustNorm") ;
        hasCustomRange = kTRUE ;
 
        coutI(Plotting) << "RooAbsPdf::plotOn(" << GetName() << ") only plotting range ["
            << rangeLo << "," << rangeHi << "]" ;
        if (!pc.hasProcessed("NormRange")) {
          ccoutI(Plotting) << ", curve is normalized to data in " << (adjustNorm?"given":"full") << " range" << endl ;
        } else {
          ccoutI(Plotting) << endl ;
        }
 
        nameSuffix.Append(Form("_Range[%f_%f]",rangeLo,rangeHi)) ;
 
      } else if (pc.hasProcessed("RangeWithName")) {
 
        for (const std::string& rangeNameToken : RooHelpers::tokenise(pc.getString("rangeName", "", false), ",", /*returnEmptyToken=*/true)) {
          const char* thisRangeName = rangeNameToken.empty() ? nullptr : rangeNameToken.c_str();
          if (thisRangeName && !frame->getPlotVar()->hasRange(thisRangeName)) {
            coutE(Plotting) << "Range '" << rangeNameToken << "' not defined for variable '"
                << frame->getPlotVar()->GetName() << "'. Ignoring ..." << std::endl;
            continue;
          }
          rangeLim.push_back(frame->getPlotVar()->getRange(thisRangeName));
        }
        adjustNorm = pc.getInt("rangeWNAdjustNorm") ;
        hasCustomRange = kTRUE ;
 
        coutI(Plotting) << "RooAbsPdf::plotOn(" << GetName() << ") only plotting range '" << pc.getString("rangeName", "", false) << "'" ;
        if (!pc.hasProcessed("NormRange")) {
          ccoutI(Plotting) << ", curve is normalized to data in " << (adjustNorm?"given":"full") << " range" << endl ;
        } else {
          ccoutI(Plotting) << endl ;
        }
 
        nameSuffix.Append(Form("_Range[%s]",pc.getString("rangeName"))) ;
      }
      // Specification of a normalization range override those in a regular range
      if (pc.hasProcessed("NormRange")) {
        rangeLim.clear();
        for (const auto& rangeNameToken : RooHelpers::tokenise(pc.getString("normRangeName", "", false), ",", /*returnEmptyToken=*/true)) {
          const char* thisRangeName = rangeNameToken.empty() ? nullptr : rangeNameToken.c_str();
          if (thisRangeName && !frame->getPlotVar()->hasRange(thisRangeName)) {
            coutE(Plotting) << "Range '" << rangeNameToken << "' not defined for variable '"
                << frame->getPlotVar()->GetName() << "'. Ignoring ..." << std::endl;
            continue;
          }
          rangeLim.push_back(frame->getPlotVar()->getRange(thisRangeName));
        }
        adjustNorm = kTRUE ;
        hasCustomRange = kTRUE ;
        coutI(Plotting) << "RooAbsPdf::plotOn(" << GetName() << ") p.d.f. curve is normalized using explicit choice of ranges '" << pc.getString("normRangeName", "", false) << "'" << endl ;
 
        nameSuffix.Append(Form("_NormRange[%s]",pc.getString("rangeName"))) ;
 
      }
 
      if (hasCustomRange && adjustNorm) {
        // If overlapping ranges were given, remove them now
        const std::size_t oldSize = rangeLim.size();
        removeRangeOverlap(rangeLim);
 
        if (oldSize != rangeLim.size() && !pc.hasProcessed("NormRange")) {
          // User gave overlapping ranges. This leads to double-counting events and integrals, and must
          // therefore be avoided. If a NormRange has been given, the overlap is alreay gone.
          // It's safe to plot even with overlap now.
          coutE(Plotting) << "Requested plot/integration ranges overlap. For correct plotting, new ranges "
              "will be defined." << std::endl;
          auto plotVar = dynamic_cast<RooRealVar*>(frame->getPlotVar());
          assert(plotVar);
          std::string rangesNoOverlap;
          for (auto it = rangeLim.begin(); it != rangeLim.end(); ++it) {
            std::stringstream rangeName;
            rangeName << "Remove_overlap_range_" << it - rangeLim.begin();
            plotVar->setRange(rangeName.str().c_str(), it->first, it->second);
            if (!rangesNoOverlap.empty())
              rangesNoOverlap += ",";
            rangesNoOverlap += rangeName.str();
          }
 
          auto rangeArg = static_cast<RooCmdArg*>(cmdList.FindObject("RangeWithName"));
          if (rangeArg)
            rangeArg->setString(0, rangesNoOverlap.c_str());
          else {
            plotRange = new RooCmdArg(RooFit::Range(rangesNoOverlap.c_str()));
            cmdList.Add(plotRange);
          }
        }
 
        Double_t rangeNevt(0) ;
        for (const auto& riter : rangeLim) {
          Double_t nevt= frame->getFitRangeNEvt(riter.first, riter.second);
          rangeNevt += nevt ;
        }
 
        scaleFactor *= rangeNevt/nExpected ;
 
      } else {
        scaleFactor *= frame->getFitRangeNEvt()/nExpected ;
      }
    } else if (stype==RelativeExpected) {
      scaleFactor *= nExpected ;
    } else if (stype==NumEvent) {
      scaleFactor /= nExpected ;
    }
    scaleFactor *= frame->getFitRangeBinW() ;
  }
  frame->updateNormVars(*frame->getPlotVar()) ;
 
  // Append overriding scale factor command at end of original command list
  RooCmdArg tmp = RooFit::Normalization(scaleFactor,Raw) ;
  tmp.setInt(1,1) ; // Flag this normalization command as created for internal use (so that VisualizeError can strip it)
  cmdList.Add(&tmp) ;
 
  // Was a component selected requested
  if (haveCompSel) {
 
    // Get complete set of tree branch nodes
    RooArgSet branchNodeSet ;
    branchNodeServerList(&branchNodeSet) ;
 
    // Discard any non-RooAbsReal nodes
    for (const auto arg : branchNodeSet) {
      if (!dynamic_cast<RooAbsReal*>(arg)) {
        branchNodeSet.remove(*arg) ;
      }
    }
 
    // Obtain direct selection
    RooArgSet* dirSelNodes ;
    if (compSet) {
      dirSelNodes = (RooArgSet*) branchNodeSet.selectCommon(*compSet) ;
    } else {
      dirSelNodes = (RooArgSet*) branchNodeSet.selectByName(compSpec) ;
    }
    if (dirSelNodes->getSize()>0) {
      coutI(Plotting) << "RooAbsPdf::plotOn(" << GetName() << ") directly selected PDF components: " << *dirSelNodes << endl ;
 
      // Do indirect selection and activate both
      plotOnCompSelect(dirSelNodes) ;
    } else {
      if (compSet) {
   coutE(Plotting) << "RooAbsPdf::plotOn(" << GetName() << ") ERROR: component selection set " << *compSet << " does not match any components of p.d.f." << endl ;
      } else {
   coutE(Plotting) << "RooAbsPdf::plotOn(" << GetName() << ") ERROR: component selection expression '" << compSpec << "' does not select any components of p.d.f." << endl ;
      }
      return 0 ;
    }
 
    delete dirSelNodes ;
  }
 
 
  RooCmdArg cnsuffix("CurveNameSuffix",0,0,0,0,nameSuffix.Data(),0,0,0) ;
  cmdList.Add(&cnsuffix);
 
  RooPlot* ret =  RooAbsReal::plotOn(frame,cmdList) ;
 
  // Restore selection status ;
  if (haveCompSel) plotOnCompSelect(0) ;
 
  if (plotRange) {
    delete plotRange ;
  }
  if (normRange2) {
    delete normRange2 ;
  }
 
  return ret ;
}
 
 
//_____________________________________________________________________________
/// Plot oneself on 'frame'. In addition to features detailed in  RooAbsReal::plotOn(),
/// the scale factor for a PDF can be interpreted in three different ways. The interpretation
/// is controlled by ScaleType
/// ```
///  Relative  -  Scale factor is applied on top of PDF normalization scale factor
///  NumEvent  -  Scale factor is interpreted as a number of events. The surface area
///               under the PDF curve will match that of a histogram containing the specified
///               number of event
///  Raw       -  Scale factor is applied to the raw (projected) probability density.
///               Not too useful, option provided for completeness.
/// ```
// coverity[PASS_BY_VALUE]
RooPlot* RooAbsPdf::plotOn(RooPlot *frame, PlotOpt o) const
{
 
  // Sanity checks
  if (plotSanityChecks(frame)) return frame ;
 
  // More sanity checks
  Double_t nExpected(1) ;
  if (o.stype==RelativeExpected) {
    if (!canBeExtended()) {
      coutE(Plotting) << "RooAbsPdf::plotOn(" << GetName()
            << "): ERROR the 'Expected' scale option can only be used on extendable PDFs" << endl ;
      return frame ;
    }
    nExpected = expectedEvents(frame->getNormVars()) ;
  }
 
  // Adjust normalization, if so requested
  if (o.stype != Raw) {
 
    if (frame->getFitRangeNEvt() && o.stype==Relative) {
      // If non-default plotting range is specified, adjust number of events in fit range
      o.scaleFactor *= frame->getFitRangeNEvt()/nExpected ;
    } else if (o.stype==RelativeExpected) {
      o.scaleFactor *= nExpected ;
    } else if (o.stype==NumEvent) {
      o.scaleFactor /= nExpected ;
    }
    o.scaleFactor *= frame->getFitRangeBinW() ;
  }
  frame->updateNormVars(*frame->getPlotVar()) ;
 
  return RooAbsReal::plotOn(frame,o) ;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// The following named arguments are supported
/// <table>
/// <tr><th> Type of CmdArg                     <th> Effect on parameter box
/// <tr><td> `Parameters(const RooArgSet& param)` <td>  Only the specified subset of parameters will be shown. By default all non-constant parameters are shown.
/// <tr><td> `ShowConstants(Bool_t flag)`         <td>  Also display constant parameters
/// <tr><td> `Format(const char* optStr)`         <td>  \deprecated Classing parameter formatting options, provided for backward compatibility
///
/// <tr><td> `Format(const char* what,...)`       <td>  Parameter formatting options.
///   | Parameter              | Format
///   | ---------------------- | --------------------------
///   | `const char* what`     |  Controls what is shown. "N" adds name, "E" adds error, "A" shows asymmetric error, "U" shows unit, "H" hides the value
///   | `FixedPrecision(int n)`|  Controls precision, set fixed number of digits
///   | `AutoPrecision(int n)` |  Controls precision. Number of shown digits is calculated from error + n specified additional digits (1 is sensible default)
/// <tr><td> `Label(const chat* label)`           <td>  Add label to parameter box. Use `\n` for multi-line labels.
/// <tr><td> `Layout(Double_t xmin, Double_t xmax, Double_t ymax)` <td>  Specify relative position of left/right side of box and top of box.
///                                                                      Coordinates are given as position on the pad between 0 and 1.
///                                                                      The lower end of the box is calculated automatically from the number of lines in the box.
/// </table>
///
///
/// Example use:
/// ```
/// pdf.paramOn(frame, Label("fit result"), Format("NEU",AutoPrecision(1)) ) ;
/// ```
///
 
RooPlot* RooAbsPdf::paramOn(RooPlot* 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)
{
  // Stuff all arguments in a list
  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)) ;
 
  // Select the pdf-specific commands
  RooCmdConfig pc(Form("RooAbsPdf::paramOn(%s)",GetName())) ;
  pc.defineString("label","Label",0,"") ;
  pc.defineDouble("xmin","Layout",0,0.50) ;
  pc.defineDouble("xmax","Layout",1,0.99) ;
  pc.defineInt("ymaxi","Layout",0,Int_t(0.95*10000)) ;
  pc.defineInt("showc","ShowConstants",0,0) ;
  pc.defineObject("params","Parameters",0,0) ;
  pc.defineString("formatStr","Format",0,"NELU") ;
  pc.defineInt("sigDigit","Format",0,2) ;
  pc.defineInt("dummy","FormatArgs",0,0) ;
  pc.defineMutex("Format","FormatArgs") ;
 
  // Process and check varargs
  pc.process(cmdList) ;
  if (!pc.ok(kTRUE)) {
    return frame ;
  }
 
  const char* label = pc.getString("label") ;
  Double_t xmin = pc.getDouble("xmin") ;
  Double_t xmax = pc.getDouble("xmax") ;
  Double_t ymax = pc.getInt("ymaxi") / 10000. ;
  Int_t showc = pc.getInt("showc") ;
 
 
  const char* formatStr = pc.getString("formatStr") ;
  Int_t sigDigit = pc.getInt("sigDigit") ;
 
  // Decode command line arguments
  RooArgSet* params = static_cast<RooArgSet*>(pc.getObject("params")) ;
  if (!params) {
    params = getParameters(frame->getNormVars()) ;
    if (pc.hasProcessed("FormatArgs")) {
      const RooCmdArg* formatCmd = static_cast<RooCmdArg*>(cmdList.FindObject("FormatArgs")) ;
      paramOn(frame,*params,showc,label,0,0,xmin,xmax,ymax,formatCmd) ;
    } else {
      paramOn(frame,*params,showc,label,sigDigit,formatStr,xmin,xmax,ymax) ;
    }
    delete params ;
  } else {
    RooArgSet* pdfParams = getParameters(frame->getNormVars()) ;
    RooArgSet* selParams = static_cast<RooArgSet*>(pdfParams->selectCommon(*params)) ;
    if (pc.hasProcessed("FormatArgs")) {
      const RooCmdArg* formatCmd = static_cast<RooCmdArg*>(cmdList.FindObject("FormatArgs")) ;
      paramOn(frame,*selParams,showc,label,0,0,xmin,xmax,ymax,formatCmd) ;
    } else {
      paramOn(frame,*selParams,showc,label,sigDigit,formatStr,xmin,xmax,ymax) ;
    }
    delete selParams ;
    delete pdfParams ;
  }
 
  return frame ;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// \deprecated Obsolete, provided for backward compatibility. Don't use.
 
RooPlot* RooAbsPdf::paramOn(RooPlot* frame, const RooAbsData* data, const char *label,
             Int_t sigDigits, Option_t *options, Double_t xmin,
             Double_t xmax ,Double_t ymax)
{
  RooArgSet* params = getParameters(data) ;
  TString opts(options) ;
  paramOn(frame,*params,opts.Contains("c"),label,sigDigits,options,xmin,xmax,ymax) ;
  delete params ;
  return frame ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Add a text box with the current parameter values and their errors to the frame.
/// Observables of this PDF appearing in the 'data' dataset will be omitted.
///
/// An optional label will be inserted if passed. Multi-line labels can be generated
/// by adding `\n` to the label string. Use 'sigDigits'
/// to modify the default number of significant digits printed. The 'xmin,xmax,ymax'
/// values specify the initial relative position of the text box in the plot frame.
 
RooPlot* RooAbsPdf::paramOn(RooPlot* frame, const RooArgSet& params, Bool_t showConstants, const char *label,
             Int_t sigDigits, Option_t *options, Double_t xmin,
             Double_t xmax ,Double_t ymax, const RooCmdArg* formatCmd)
{
 
  // parse the options
  TString opts = options;
  opts.ToLower();
  Bool_t showLabel= (label != 0 && strlen(label) > 0);
 
  // calculate the box's size, adjusting for constant parameters
 
  Double_t ymin(ymax), dy(0.06);
  for (const auto param : params) {
    auto var = static_cast<RooRealVar*>(param);
    if(showConstants || !var->isConstant()) ymin-= dy;
  }
 
  std::string labelString = label;
  unsigned int numLines = std::count(labelString.begin(), labelString.end(), '\n') + 1;
  if (showLabel) ymin -= numLines * dy;
 
  // create the box and set its options
  TPaveText *box= new TPaveText(xmin,ymax,xmax,ymin,"BRNDC");
  if(!box) return 0;
  box->SetName(Form("%s_paramBox",GetName())) ;
  box->SetFillColor(0);
  box->SetBorderSize(1);
  box->SetTextAlign(12);
  box->SetTextSize(0.04F);
  box->SetFillStyle(1001);
  box->SetFillColor(0);
 
  for (const auto param : params) {
    auto var = static_cast<const RooRealVar*>(param);
    if(var->isConstant() && !showConstants) continue;
 
    TString *formatted= options ? var->format(sigDigits, options) : var->format(*formatCmd) ;
    box->AddText(formatted->Data());
    delete formatted;
  }
 
  // add the optional label if specified
  if (showLabel) {
    for (const auto& line : RooHelpers::tokenise(label, "\n")) {
      box->AddText(line.c_str());
    }
  }
 
  // Add box to frame
  frame->addObject(box) ;
 
  return frame ;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return expected number of events from this p.d.f for use in extended
/// likelihood calculations. This default implementation returns zero
 
Double_t RooAbsPdf::expectedEvents(const RooArgSet*) const
{
  return 0 ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Change global level of verbosity for p.d.f. evaluations
 
void RooAbsPdf::verboseEval(Int_t stat)
{
  _verboseEval = stat ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return global level of verbosity for p.d.f. evaluations
 
Int_t RooAbsPdf::verboseEval()
{
  return _verboseEval ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Dummy implementation
 
void RooAbsPdf::CacheElem::operModeHook(RooAbsArg::OperMode)
{
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor of normalization cache element. If this element
/// provides the 'current' normalization stored in RooAbsPdf::_norm
/// zero _norm pointer here before object pointed to is deleted here
 
RooAbsPdf::CacheElem::~CacheElem()
{
  // Zero _norm pointer in RooAbsPdf if it is points to our cache payload
  if (_owner) {
    RooAbsPdf* pdfOwner = static_cast<RooAbsPdf*>(_owner) ;
    if (pdfOwner->_norm == _norm) {
      pdfOwner->_norm = 0 ;
    }
  }
 
  delete _norm ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return a p.d.f that represent a projection of this p.d.f integrated over given observables
 
RooAbsPdf* RooAbsPdf::createProjection(const RooArgSet& iset)
{
  // Construct name for new object
  TString name(GetName()) ;
  name.Append("_Proj[") ;
  if (iset.getSize()>0) {
    TIterator* iter = iset.createIterator() ;
    RooAbsArg* arg ;
    Bool_t first(kTRUE) ;
    while((arg=(RooAbsArg*)iter->Next())) {
      if (first) {
   first=kFALSE ;
      } else {
   name.Append(",") ;
      }
      name.Append(arg->GetName()) ;
    }
    delete iter ;
  }
  name.Append("]") ;
 
  // Return projected p.d.f.
  return new RooProjectedPdf(name.Data(),name.Data(),*this,iset) ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Create a cumulative distribution function of this p.d.f in terms
/// of the observables listed in iset. If no nset argument is given
/// the c.d.f normalization is constructed over the integrated
/// observables, so that its maximum value is precisely 1. It is also
/// possible to choose a different normalization for
/// multi-dimensional p.d.f.s: eg. for a pdf f(x,y,z) one can
/// construct a partial cdf c(x,y) that only when integrated itself
/// over z results in a maximum value of 1. To construct such a cdf pass
/// z as argument to the optional nset argument
 
RooAbsReal* RooAbsPdf::createCdf(const RooArgSet& iset, const RooArgSet& nset)
{
  return createCdf(iset,RooFit::SupNormSet(nset)) ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Create an object that represents the integral of the function over one or more observables listed in `iset`.
/// The actual integration calculation is only performed when the return object is evaluated. The name
/// of the integral object is automatically constructed from the name of the input function, the variables
/// it integrates and the range integrates over
///
/// The following named arguments are accepted
/// | Type of CmdArg    |    Effect on CDF
/// | ---------------------|-------------------
/// | SupNormSet(const RooArgSet&)         | Observables over which should be normalized _in addition_ to the integration observables
/// | ScanNumCdf()                         | Apply scanning technique if cdf integral involves numeric integration [ default ]
/// | ScanAllCdf()                         | Always apply scanning technique
/// | ScanNoCdf()                          | Never apply scanning technique
/// | ScanParameters(Int_t nbins, Int_t intOrder) | Parameters for scanning technique of making CDF: number of sampled bins and order of interpolation applied on numeric cdf
 
RooAbsReal* RooAbsPdf::createCdf(const RooArgSet& iset, const RooCmdArg& arg1, const RooCmdArg& arg2,
             const RooCmdArg& arg3, const RooCmdArg& arg4, const RooCmdArg& arg5,
             const RooCmdArg& arg6, const RooCmdArg& arg7, const RooCmdArg& arg8)
{
  // Define configuration for this method
  RooCmdConfig pc(Form("RooAbsReal::createCdf(%s)",GetName())) ;
  pc.defineObject("supNormSet","SupNormSet",0,0) ;
  pc.defineInt("numScanBins","ScanParameters",0,1000) ;
  pc.defineInt("intOrder","ScanParameters",1,2) ;
  pc.defineInt("doScanNum","ScanNumCdf",0,1) ;
  pc.defineInt("doScanAll","ScanAllCdf",0,0) ;
  pc.defineInt("doScanNon","ScanNoCdf",0,0) ;
  pc.defineMutex("ScanNumCdf","ScanAllCdf","ScanNoCdf") ;
 
  // Process & check varargs
  pc.process(arg1,arg2,arg3,arg4,arg5,arg6,arg7,arg8) ;
  if (!pc.ok(kTRUE)) {
    return 0 ;
  }
 
  // Extract values from named arguments
  const RooArgSet* snset = static_cast<const RooArgSet*>(pc.getObject("supNormSet",0)) ;
  RooArgSet nset ;
  if (snset) {
    nset.add(*snset) ;
  }
  Int_t numScanBins = pc.getInt("numScanBins") ;
  Int_t intOrder = pc.getInt("intOrder") ;
  Int_t doScanNum = pc.getInt("doScanNum") ;
  Int_t doScanAll = pc.getInt("doScanAll") ;
  Int_t doScanNon = pc.getInt("doScanNon") ;
 
  // If scanning technique is not requested make integral-based cdf and return
  if (doScanNon) {
    return createIntRI(iset,nset) ;
  }
  if (doScanAll) {
    return createScanCdf(iset,nset,numScanBins,intOrder) ;
  }
  if (doScanNum) {
    RooRealIntegral* tmp = (RooRealIntegral*) createIntegral(iset) ;
    Int_t isNum= (tmp->numIntRealVars().getSize()>0) ;
    delete tmp ;
 
    if (isNum) {
      coutI(NumIntegration) << "RooAbsPdf::createCdf(" << GetName() << ") integration over observable(s) " << iset << " involves numeric integration," << endl
             << "      constructing cdf though numeric integration of sampled pdf in " << numScanBins << " bins and applying order "
             << intOrder << " interpolation on integrated histogram." << endl
             << "      To override this choice of technique use argument ScanNone(), to change scan parameters use ScanParameters(nbins,order) argument" << endl ;
    }
 
    return isNum ? createScanCdf(iset,nset,numScanBins,intOrder) : createIntRI(iset,nset) ;
  }
  return 0 ;
}
 
RooAbsReal* RooAbsPdf::createScanCdf(const RooArgSet& iset, const RooArgSet& nset, Int_t numScanBins, Int_t intOrder)
{
  string name = string(GetName()) + "_NUMCDF_" + integralNameSuffix(iset,&nset).Data() ;
  RooRealVar* ivar = (RooRealVar*) iset.first() ;
  ivar->setBins(numScanBins,"numcdf") ;
  RooNumCdf* ret = new RooNumCdf(name.c_str(),name.c_str(),*this,*ivar,"numcdf") ;
  ret->setInterpolationOrder(intOrder) ;
  return ret ;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// This helper function finds and collects all constraints terms of all component p.d.f.s
/// and returns a RooArgSet with all those terms.
 
RooArgSet* RooAbsPdf::getAllConstraints(const RooArgSet& observables, RooArgSet& constrainedParams, Bool_t stripDisconnected) const
{
  RooArgSet* ret = new RooArgSet("AllConstraints") ;
 
  std::unique_ptr<RooArgSet> comps(getComponents());
  for (const auto arg : *comps) {
    auto pdf = dynamic_cast<const RooAbsPdf*>(arg) ;
    if (pdf && !ret->find(pdf->GetName())) {
      std::unique_ptr<RooArgSet> compRet(pdf->getConstraints(observables,constrainedParams,stripDisconnected));
      if (compRet) {
        ret->add(*compRet,kFALSE) ;
      }
    }
  }
 
  return ret ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the default numeric MC generator configuration for all RooAbsReals
 
RooNumGenConfig* RooAbsPdf::defaultGeneratorConfig()
{
  return &RooNumGenConfig::defaultConfig() ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the specialized integrator configuration for _this_ RooAbsReal.
/// If this object has no specialized configuration, a null pointer is returned
 
RooNumGenConfig* RooAbsPdf::specialGeneratorConfig() const
{
  return _specGeneratorConfig ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the specialized integrator configuration for _this_ RooAbsReal.
/// If this object has no specialized configuration, a null pointer is returned,
/// unless createOnTheFly is kTRUE in which case a clone of the default integrator
/// configuration is created, installed as specialized configuration, and returned
 
RooNumGenConfig* RooAbsPdf::specialGeneratorConfig(Bool_t createOnTheFly)
{
  if (!_specGeneratorConfig && createOnTheFly) {
    _specGeneratorConfig = new RooNumGenConfig(*defaultGeneratorConfig()) ;
  }
  return _specGeneratorConfig ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return the numeric MC generator configuration used for this object. If
/// a specialized configuration was associated with this object, that configuration
/// is returned, otherwise the default configuration for all RooAbsReals is returned
 
const RooNumGenConfig* RooAbsPdf::getGeneratorConfig() const
{
  const RooNumGenConfig* config = specialGeneratorConfig() ;
  if (config) return config ;
  return defaultGeneratorConfig() ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Set the given configuration as default numeric MC generator
/// configuration for this object
 
void RooAbsPdf::setGeneratorConfig(const RooNumGenConfig& config)
{
  if (_specGeneratorConfig) {
    delete _specGeneratorConfig ;
  }
  _specGeneratorConfig = new RooNumGenConfig(config) ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Remove the specialized numeric MC generator configuration associated
/// with this object
 
void RooAbsPdf::setGeneratorConfig()
{
  if (_specGeneratorConfig) {
    delete _specGeneratorConfig ;
  }
  _specGeneratorConfig = 0 ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
 
RooAbsPdf::GenSpec::~GenSpec()
{
  delete _genContext ;
}
 
 
////////////////////////////////////////////////////////////////////////////////
 
RooAbsPdf::GenSpec::GenSpec(RooAbsGenContext* context, const RooArgSet& whatVars, RooDataSet* protoData, Int_t nGen,
             Bool_t extended, Bool_t randProto, Bool_t resampleProto, TString dsetName, Bool_t init) :
  _genContext(context), _whatVars(whatVars), _protoData(protoData), _nGen(nGen), _extended(extended),
  _randProto(randProto), _resampleProto(resampleProto), _dsetName(dsetName), _init(init)
{
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
 
void RooAbsPdf::setNormRange(const char* rangeName)
{
  if (rangeName) {
    _normRange = rangeName ;
  } else {
    _normRange.Clear() ;
  }
 
  if (_norm) {
    _normMgr.sterilize() ;
    _norm = 0 ;
  }
}
 
 
////////////////////////////////////////////////////////////////////////////////
 
void RooAbsPdf::setNormRangeOverride(const char* rangeName)
{
  if (rangeName) {
    _normRangeOverride = rangeName ;
  } else {
    _normRangeOverride.Clear() ;
  }
 
  if (_norm) {
    _normMgr.sterilize() ;
    _norm = 0 ;
  }
}