include/Geant4/G4SimpleIntegration.hh

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0025 //
0026 // G4SimpleIntegration
0027 //
0028 // Class description:
0029 //
0030 // Class for realisation of simple numerical methodes for integration of
0031 // functions with signature: double f(double). The methods based mainly on
0032 // algorithms given in the book:
0033 //   An introduction to NUMERICAL METHODS IN C++,
0034 //   B.H. Flowers, Claredon Press, Oxford, 1995.
0035
0036 // Author: V.Grichine, 26.03.1997
0037 // --------------------------------------------------------------------
0038 #ifndef G4SIMPLEINTEGRATION_HH
0039 #define G4SIMPLEINTEGRATION_HH 1
0040
0041 #include "G4Types.hh"
0042
0043 using function = G4double (*)(G4double);
0044
0045 class G4SimpleIntegration
0046 {
0047  public:
0048   explicit G4SimpleIntegration(function pFunction);
0049
0050   G4SimpleIntegration(function pFunction, G4double pTolerance);
0051
0052   ~G4SimpleIntegration() = default;
0053
0054   G4SimpleIntegration(const G4SimpleIntegration&) = delete;
0055   G4SimpleIntegration& operator=(const G4SimpleIntegration&) = delete;
0056   // Private copy constructor and assignment operator.
0057
0058   // Simple integration methods:
0059   // Trapezoidal, MidPoint, Gauss and Simpson(double a,double b,int n)
0060   // - integrate function pointed by fFunction from a to b by n iterations,
0061   //   i.e. with Step (b-a)/n according to the correspondent method.
0062
0063   G4double Trapezoidal(G4double xInitial, G4double xFinal,
0064                        G4int iterationNumber);
0065
0066   G4double MidPoint(G4double xInitial, G4double xFinal, G4int iterationNumber);
0067
0068   G4double Gauss(G4double xInitial, G4double xFinal, G4int iterationNumber);
0069
0070   G4double Simpson(G4double xInitial, G4double xFinal, G4int iterationNumber);
0071
0072   // Adaptive Gauss integration with accuracy ~ fTolerance
0073
0074   G4double AdaptGaussIntegration(G4double xInitial, G4double xFinal);
0075   // Integrate function from a to be with accuracy <= fTolerance
0076
0077  protected:
0078   G4double Gauss(G4double xInitial, G4double xFinal);
0079
0080   void AdaptGauss(G4double xInitial, G4double xFinal, G4double& sum,
0081                   G4int& depth);
0082
0083  private:
0084   function fFunction;              // pointer to the function to be integrated
0085   G4double fTolerance   = 0.0001;  // accuracy of integration
0086   const G4int fMaxDepth = 100;     // constant maximum iteration depth
0087 };
0088
0089 #endif