eicsmear/smear/Device.h

0001 /**
0002  \file
0003  Declaration of class Smear::Device.
0004
0005  \author    Michael Savastio
0006  \date      2011-08-19
0007  \copyright 2011 Brookhaven National Lab
0008  */
0009
0010 #ifndef INCLUDE_EICSMEAR_SMEAR_DEVICE_H_
0011 #define INCLUDE_EICSMEAR_SMEAR_DEVICE_H_
0012
0013 #include <cmath>
0014 #include <vector>
0015
0016 #include <Math/ParamFunctor.h>  // For ROOT::TMath::ParamFunctor
0017 #include <TF1.h>
0018 #include <TF2.h>
0019 #include <TRandom3.h>
0020 #include <TString.h>
0021
0022 #include "eicsmear/smear/Acceptance.h"
0023 #include "eicsmear/smear/Distributor.h"
0024 #include "eicsmear/smear/Smear.h"
0025 #include "eicsmear/smear/Smearer.h"
0026
0027 class TRandom3;
0028
0029 namespace erhic {
0030
0031 class VirtualParticle;
0032
0033 }  // namespace erhic
0034
0035 namespace Smear {
0036
0037 class FormulaString;
0038 class ParticleMCS;
0039
0040 /**
0041  Performs smearing of a single kinematic variable according to a simple
0042  expression defined via a string.
0043  */
0044 class Device : public Smearer {
0045  public:
0046   /**
0047    Constructor.
0048    The first argument is the type of kinematic variable to smear.
0049    The second argument is a formula giving the width of the
0050    resolution in the variable selected with the first argument, i.e.
0051    sigma(A) = f(B, C...)
0052    where A, B, C... are selected from: E, P, theta, phi, pZ and pT, A
0053    is the variable type given for the first argument and B, C... are
0054    the variables listed in the formula.
0055    For example, for resolution in pT of 1% pT times sin of polar angle:
0056    Smear::Device(Smear::kPt, "0.01 * pT * sin(theta)");
0057    See ROOT::TFormula for the form of valid expressions.
0058    Formulae can be a function of up to four variables.
0059    The third argument allows selection of the types of particles that are
0060    smeared: electromagnetic, hadronic or all.
0061    */
0062   Device(KinType = kE, const TString& formula = "0", EGenre = kAll);
0063
0064   /**
0065    Constructor for smearing with an arbitrary function of a single variable.
0066    The first argument is a function of E, P, theta, phi, pT, or pZ.
0067    See ROOT::TFormula for syntax.
0068    For example, to smear in 1/pT:
0069    Smear::Device('1/pT', '<some resolution function>')
0070    */
0071   Device(const TString&, const TString& resolution = "0", EGenre = kAll);
0072
0073   /**
0074    Copy constructor.
0075    */
0076   Device(const Device&);
0077
0078   /**
0079    Destructor.
0080    */
0081   virtual ~Device();
0082
0083   /**
0084    Returns a dynamically allocated copy of this object.
0085    The argument is unused and is present for compatibility with
0086    ROOT::TObject::Clone().
0087    */
0088   virtual Device* Clone(const char* = "") const;
0089
0090   /**
0091    Smear the kinematic value of the input particle and store the
0092    result in the ParticleMCS.
0093    Smearing works in the following way. If we smear a variable
0094    VirtualParticle.X == x with parametrization f(x),
0095    then z[x,f(x)] will be stored in ParticleMCS.X, where z is a
0096    randomly generated number from a distribution of which x is
0097    the mean and f(xi) is the standard deviation.
0098    By default a Gaussian distribution is used.
0099    Use SetDistribution() for other distributions
0100    (and see Smear::Distributor).
0101    */
0102   virtual void Smear(const erhic::VirtualParticle&, ParticleMCS&);
0103
0104   /**
0105    Set the random distribution from which to sample smeared kinematics.
0106    By default a Gaussian distribution is used.
0107    */
0108   virtual void SetDistribution(const Distributor&);
0109
0110   /**
0111    Print information about this device to standard output.
0112    */
0113   virtual void Print(Option_t* = "") const;
0114
0115  protected:
0116   bool Init(const TString&, const TString&, int);
0117
0118   KinType mSmeared;   ///< Smeared variable
0119   TF1* mKinematicFunction;
0120   FormulaString* mFormula;  ///< Expression for resolution standard deviation
0121   std::vector<Smear::KinType> mDimensions;  ///< Variables on which smearing
0122                                             ///< is dependent (up to 4)
0123   Distributor mDistribution;  ///< Random distribution
0124
0125  private:
0126   // Assignment is not supported
0127   Device& operator=(const Device&) { return *this; }
0128
0129   ClassDef(Smear::Device, 1)
0130 };
0131
0132 inline void Device::SetDistribution(const Distributor& d) {
0133   mDistribution = d;
0134 }
0135
0136 }  // namespace Smear
0137
0138 #endif  // INCLUDE_EICSMEAR_SMEAR_DEVICE_H_