eicsmear/smear/FormulaString.h

0001 /**
0002  \file
0003  Declaration of class Smear::FormulaString.
0004
0005  \author    Michael Savastio
0006  \date      2011-08-19
0007  \copyright 2011 Brookhaven National Lab
0008  */
0009
0010 #ifndef INCLUDE_EICSMEAR_SMEAR_FORMULASTRING_H_
0011 #define INCLUDE_EICSMEAR_SMEAR_FORMULASTRING_H_
0012
0013 #include <string>
0014 #include <vector>
0015
0016 #include <TObject.h>
0017
0018 #include "eicsmear/smear/Smear.h"  // For KinType enum
0019
0020 class TFormula;
0021
0022 namespace Smear {
0023
0024 /**
0025  A formula described by a string with up to four variables.
0026  */
0027 class FormulaString : public TObject {
0028  public:
0029   /**
0030    Destructor.
0031    */
0032   virtual ~FormulaString();
0033
0034   /**
0035    Default construtor.
0036    Only present to meet ROOT requirements for objects to have a default
0037    constructor.
0038    Always evaluates to zero.
0039    */
0040   FormulaString();
0041
0042   /**
0043    Initialise with a string describing the formula.
0044    Formula syntax is as for ROOT::TFormula.
0045    Valid variable names are:
0046    <ul>
0047    <li>"E"</li>
0048    <li>"P"</li>
0049    <li>"theta"</li>
0050    <li>"phi"</li>
0051    <li>"pZ"</li>
0052    <li>"pT"</li>
0053    </ul>
0054    Variable names ARE case sensitive.
0055    Energy (momentum) are in GeV(/c), angles are in radians.
0056    e.g. for the function p/sin(theta)
0057    Smear::FormulaString("P/sin(theta)");
0058    */
0059   explicit FormulaString(const std::string&);
0060
0061   /**
0062    Evaluate the formula with the provided arguments.
0063    Arguments should be listed in the order they were
0064    named in the constructor string.
0065    e.g. if the input function was "P/sin(theta)" pass a vector with
0066    element 0 == 0.5 and element 1 == 3 to evaluate at P == 0.5 and
0067    theta == 3.
0068    */
0069   virtual double Eval(const std::vector<double>&) const;
0070
0071   /**
0072    Returns a vector of Smear::KinType corresponding to the variables
0073    named in the constructor string.
0074    e.g. If initialised with "P/sin(theta)", would result in a vector with
0075    two elements: kP, kTheta.
0076    */
0077   virtual std::vector<Smear::KinType> Variables() const;
0078
0079   /**
0080    Returns the processed formula string with variables substituted.
0081    */
0082   virtual std::string GetString() const;
0083
0084   /**
0085    Returns the unprocessed input formula string.
0086    */
0087   virtual std::string GetInputString() const;
0088
0089   /**
0090    Returns the name corresponding the a Smear::KinType.
0091    */
0092   static std::string GetKinName(KinType);
0093
0094   /**
0095    Returns the KinType corresponding to the variable name,
0096    or kInvalidKinType if the name is invalid.
0097    */
0098   static KinType GetKinType(const std::string&);
0099
0100  protected:
0101   /**
0102    Process the input string, containing "P", "theta" etc into a version
0103    with "x", "y", "z", "t" substituted, compatible with TFormula.
0104    */
0105   std::string Parse(const std::string&);
0106
0107   TFormula* mFormula;
0108   std::string mInput;  ///< Original formula (before parsing)
0109   std::vector<Smear::KinType> mVariables;
0110
0111   ClassDef(Smear::FormulaString, 1)
0112 };
0113
0114 }  // namespace Smear
0115
0116 #endif  // INCLUDE_EICSMEAR_SMEAR_FORMULASTRING_H_