RooGExpModel.h

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/*****************************************************************************
 * Project: RooFit                                                           *
 * Package: RooFitModels                                                     *
 *    File: $Id: RooGExpModel.h,v 1.16 2007/05/11 09:13:07 verkerke 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)             *
 *****************************************************************************/
#ifndef ROO_GEXP_MODEL
#define ROO_GEXP_MODEL

#include <cmath>
#include <complex>

#include "Rtypes.h"
#include "RooResolutionModel.h"
#include "RooRealProxy.h"
#include "RooMath.h"

class RooGExpModel : public RooResolutionModel {
public:

  enum RooGExpBasis { noBasis=0, expBasisMinus= 1, expBasisSum= 2, expBasisPlus= 3,
                       sinBasisMinus=11, sinBasisSum=12, sinBasisPlus=13,
                                 cosBasisMinus=21, cosBasisSum=22, cosBasisPlus=23, 
             sinhBasisMinus=31,sinhBasisSum=32,sinhBasisPlus=33,
             coshBasisMinus=41,coshBasisSum=42,coshBasisPlus=43} ;
  


  enum BasisType { none=0, expBasis=1, sinBasis=2, cosBasis=3, sinhBasis=4, coshBasis=5 } ;
  enum BasisSign { Both=0, Plus=+1, Minus=-1 } ;
  enum Type { Normal, Flipped };  

  // Constructors, assignment etc
  inline RooGExpModel() { 
    // coverity[UNINIT_CTOR]
  }
  RooGExpModel(const char *name, const char *title, RooRealVar& x, 
          RooAbsReal& sigma, RooAbsReal& rlife, 
          Bool_t nlo=kFALSE, Type type=Normal) ; 

  RooGExpModel(const char *name, const char *title, RooRealVar& x, 
          RooAbsReal& sigma, RooAbsReal& rlife, 
          RooAbsReal& srSF, 
          Bool_t nlo=kFALSE, Type type=Normal) ; 

  RooGExpModel(const char *name, const char *title, RooRealVar& x, 
          RooAbsReal& sigma, RooAbsReal& rlife, 
          RooAbsReal& sigmaSF, RooAbsReal& rlifeSF,
          Bool_t nlo=kFALSE, Type type=Normal) ; 

  RooGExpModel(const RooGExpModel& other, const char* name=0);
  virtual TObject* clone(const char* newname) const { return new RooGExpModel(*this,newname) ; }
  virtual ~RooGExpModel();
  
  virtual Int_t basisCode(const char* name) const ;
  virtual Int_t getAnalyticalIntegral(RooArgSet& allVars, RooArgSet& analVars, const char* rangeName=0) const ;
  virtual Double_t analyticalIntegral(Int_t code, const char* rangeName=0) const ;

  Int_t getGenerator(const RooArgSet& directVars, RooArgSet &generateVars, Bool_t staticInitOK=kTRUE) const;
  void generateEvent(Int_t code);

  void advertiseFlatScaleFactorIntegral(Bool_t flag) { _flatSFInt = flag ; }

  void advertiseAsymptoticIntegral(Bool_t flag) { _asympInt = flag ; }  // added FMV,07/24/03

protected:

  Double_t logErfC(Double_t x) const ;

  //Double_t calcDecayConv(Double_t sign, Double_t tau, Double_t sig, Double_t rtau) const ;
  Double_t calcDecayConv(Double_t sign, Double_t tau, Double_t sig, Double_t rtau, Double_t fsign) const ;  
   // modified FMV,08/13/03
  std::complex<Double_t> calcSinConv(Double_t sign, Double_t sig, Double_t tau, Double_t omega, Double_t rtau, Double_t fsign) const ;
  Double_t calcSinConv(Double_t sign, Double_t sig, Double_t tau, Double_t rtau, Double_t fsign) const ;
  std::complex<Double_t> calcSinConvNorm(Double_t sign, Double_t tau, Double_t omega, 
                        Double_t sig, Double_t rtau, Double_t fsign, const char* rangeName) const ; // modified FMV,07/24/03
  Double_t calcSinConvNorm(Double_t sign, Double_t tau, 
        Double_t sig, Double_t rtau, Double_t fsign, const char* rangeName) const ; // added FMV,08/18/03
  //Double_t calcSinhConv(Double_t sign, Double_t sign1, Double_t sign2, Double_t tau, Double_t dgamma, Double_t sig, Double_t rtau, Double_t fsign) const ;
  //Double_t calcCoshConv(Double_t sign, Double_t tau, Double_t dgamma, Double_t sig, Double_t rtau, Double_t fsign) const ;
  virtual Double_t evaluate() const ;
  static std::complex<Double_t> evalCerfApprox(Double_t swt, Double_t u, Double_t c);

  // Calculate exp(-u^2) cwerf(swt*c + i(u+c)), taking care of numerical instabilities
  static inline std::complex<Double_t> evalCerf(Double_t swt, Double_t u, Double_t c)
  {
    std::complex<Double_t> z(swt*c,u+c);
    return (z.imag()>-4.0) ? RooMath::faddeeva_fast(z)*std::exp(-u*u) : evalCerfApprox(swt,u,c) ;
  }
    
  // Calculate Re(exp(-u^2) cwerf(i(u+c)))
  // added FMV, 08/17/03
  inline Double_t evalCerfRe(Double_t u, Double_t c) const {
    Double_t expArg = u*2*c+c*c ;
    if (expArg<300) {
       return exp(expArg) * RooMath::erfc(u+c);
    } else {
       return exp(expArg+logErfC(u+c));
    }
  }

  // Calculate common normalization factors 
  // added FMV,07/24/03
  std::complex<Double_t> evalCerfInt(Double_t sign, Double_t wt, Double_t tau, Double_t umin, Double_t umax, Double_t c) const ;
  Double_t evalCerfInt(Double_t sign, Double_t tau, Double_t umin, Double_t umax, Double_t c) const ;

  RooRealProxy sigma ;
  RooRealProxy rlife ;
  RooRealProxy ssf ;
  RooRealProxy rsf ;
  Bool_t _flip ;
  Bool_t _nlo ;
  Bool_t _flatSFInt ;
  Bool_t _asympInt ;  // added FMV,07/24/03

  ClassDef(RooGExpModel,1) // Gauss (x) Expontial resolution model
};

#endif