/*****************************************************************************
 * Project: RooFit                                                           *
 * Package: RooFitCore                                                       *
 *    File: $Id: RooNumConvPdf.cc,v 1.8 2005/06/20 15:44:55 wverkerke Exp $
 * Authors:                                                                  *
 *   WV, Wouter Verkerke, UC Santa Barbara, verkerke@slac.stanford.edu       *
 *   DK, David Kirkby,    UC Irvine,         dkirkby@uci.edu                 *
 *                                                                           *
 * Copyright (c) 2000-2005, Regents of the University of California          *
 *                          and Stanford University. All rights reserved.    *
 *                                                                           *
 * Redistribution and use in source and binary forms,                        *
 * with or without modification, are permitted according to the terms        *
 * listed in LICENSE (http://roofit.sourceforge.net/license.txt)             *
 *****************************************************************************/

// -- CLASS DESCRIPTION [PDF] --
// Numeric 1-dimensional convolution operator PDF. This class can convolve any PDF
// with any other PDF
//
// This class should not be used blindly as numeric convolution is computing
// intensive and prone to stability fitting problems. If an analytic convolution
// can be calculated, you should use that or implement it if not available.
// RooNumConvPdf implements reasonable defaults that should convolve most
// functions reasonably well, but results strongly depend on the shape of your
// input PDFS so always check your result.
//
// The default integration engine for the numeric convolution is the
// adaptive Gauss-Kronrod method, which empirically seems the most robust
// for this task. You can override the convolution integration settings via
// the RooNumIntConfig object reference returned by the convIntConfig() member
// function
//
// By default the numeric convolution is integrated from -infinity to
// +infinity through a x -> 1/x coordinate transformation of the
// tails. For convolution with a very small bandwidth it may be
// advantageous (for both CPU consumption and stability) if the
// integration domain is limited to a finite range. The function
// setConvolutionWindow(mean,width,scale) allows to set a sliding
// window around the x value to be calculated taking a RooAbsReal
// expression for an offset and a width to be taken around the x
// value. These input expression can be RooFormulaVars or other
// function objects although the 3d 'scale' argument 'scale'
// multiplies the width RooAbsReal expression given in the 2nd
// argument, allowing for an appropriate window definition for most
// cases without need for a RooFormulaVar object: e.g. a Gaussian
// resolution PDF do setConvolutionWindow(gaussMean,gaussSigma,5)
// Note that for a 'wide' Gaussian the -inf to +inf integration
// may converge more quickly than that over a finite range!
//
// The default numeric precision is 1e-7, i.e. the global default for
// numeric integration but you should experiment with this value to
// see if it is sufficient for example by studying the number of function
// calls that MINUIT needs to fit your function as function of the
// convolution precision. 

#include "RooFit.h"

#include "Riostream.h"
#include "Riostream.h"
#include "TH2F.h"
#include "RooNumConvPdf.h"
#include "RooArgList.h"
#include "RooRealVar.h"
#include "RooFormulaVar.h"
#include "RooCustomizer.h"
#include "RooConvIntegrandBinding.h"
#include "RooNumIntFactory.h"
#include "RooGenContext.h"
#include "RooConvGenContext.h"



ClassImp(RooNumConvPdf)
;


 RooNumConvPdf::RooNumConvPdf(const char *name, const char *title, RooRealVar& convVar, RooAbsPdf& pdf, RooAbsPdf& resmodel) : 
  RooAbsPdf(name,title), 
  _init(kFALSE),
  _conv(0),
  _origVar("origVar","Original Convolution variable",this,convVar),
  _origPdf("origPdf","Original Input PDF",this,pdf),
  _origModel("origModel","Original Resolution model",this,resmodel)
{
  // Constructor of convolution operator PDF
  // 
  // convVar  :  convolution variable (on which both pdf and resmodel should depend)
  // pdf      :  input 'physics' pdf
  // resmodel :  input 'resultion' pdf
  //
  // output is pdf(x) (X) resmodel(x) = Int [ pdf(x') resmodel (x-x') ] dx'
  //
}



 RooNumConvPdf::RooNumConvPdf(const RooNumConvPdf& other, const char* name) :
  RooAbsPdf(other,name), 
  _init(kFALSE),
  _origVar("origVar",this,other._origVar),
  _origPdf("origPdf",this,other._origPdf),
  _origModel("origModel",this,other._origModel)
{
  // Copy constructor

  // Make temporary clone of original convolution to preserve configuration information
  // This information will be propagated to a newly create convolution in a subsequent
  // call to initialize() 
  if (other._conv) {
    _conv = new RooNumConvolution(*other._conv,Form("%s_CONV",name?name:GetName())) ;
  } else {
    _conv = 0 ;
  }
}



 RooNumConvPdf::~RooNumConvPdf() 
{
  // Destructor
  if (_init) {
    delete _conv ;
  }
}


 Double_t RooNumConvPdf::evaluate() const
{
  if (!_init) initialize() ;

  return _conv->evaluate() ;
}


 void RooNumConvPdf::initialize() const
{
  // Save pointer to any prototype convolution object (only present if this object is made through
  // a copy constructor) 
  RooNumConvolution* protoConv = _conv ;

  // Optionally pass along configuration data from prototype object
  _conv = new RooNumConvolution(Form("%s_CONV",GetName()),GetTitle(),var(),pdf(),model(),protoConv) ;

  // Delete prototype object now
  if (protoConv) {
    delete protoConv ;  
  }

  _init = kTRUE ;
}



 RooAbsGenContext* RooNumConvPdf::genContext(const RooArgSet &vars, const RooDataSet *prototype, 
					    const RooArgSet* auxProto, Bool_t verbose) const 
{
  if (!_init) initialize() ;

  // Check if physics PDF and resolution model can both directly generate the convolution variable
  RooArgSet* modelDep = _conv->model().getObservables(&vars) ;
  modelDep->remove(_conv->var(),kTRUE,kTRUE) ;
  Int_t numAddDep = modelDep->getSize() ;
  delete modelDep ;

  RooArgSet dummy ;
  Bool_t pdfCanDir = (((RooAbsPdf&)_conv->pdf()).getGenerator(_conv->var(),dummy) != 0 && \
		      ((RooAbsPdf&)_conv->pdf()).isDirectGenSafe(_conv->var())) ;
  Bool_t resCanDir = (((RooAbsPdf&)_conv->model()).getGenerator(_conv->var(),dummy) !=0  && 
		      ((RooAbsPdf&)_conv->model()).isDirectGenSafe(_conv->var())) ;

  if (numAddDep>0 || !pdfCanDir || !resCanDir) {
    // Any resolution model with more dependents than the convolution variable
    // or pdf or resmodel do not support direct generation
    return new RooGenContext(*this,vars,prototype,auxProto,verbose) ;
  } 
  
  // Any other resolution model: use specialized generator context
  return new RooConvGenContext(*this,vars,prototype,auxProto,verbose) ;
}