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25 //
26 // G4SimpleIntegration
27 //
28 // Class description:
29 //
30 // Class for realisation of simple numerical methodes for integration of
31 // functions with signature: double f(double). The methods based mainly on
32 // algorithms given in the book:
33 // An introduction to NUMERICAL METHODS IN C++,
34 // B.H. Flowers, Claredon Press, Oxford, 1995.
35
36 // Author: V.Grichine, 26.03.1997
37 // --------------------------------------------------------------------
38 #ifndef G4SIMPLEINTEGRATION_HH
39 #define G4SIMPLEINTEGRATION_HH 1
40
41 #include "G4Types.hh"
42
43 using function = G4double (*)(G4double);
44
45 class G4SimpleIntegration
46 {
47 public:
48 explicit G4SimpleIntegration(function pFunction);
49
50 G4SimpleIntegration(function pFunction, G4double pTolerance);
51
52 ~G4SimpleIntegration() = default;
53
54 G4SimpleIntegration(const G4SimpleIntegration&) = delete;
55 G4SimpleIntegration& operator=(const G4SimpleIntegration&) = delete;
56 // Private copy constructor and assignment operator.
57
58 // Simple integration methods:
59 // Trapezoidal, MidPoint, Gauss and Simpson(double a,double b,int n)
60 // - integrate function pointed by fFunction from a to b by n iterations,
61 // i.e. with Step (b-a)/n according to the correspondent method.
62
63 G4double Trapezoidal(G4double xInitial, G4double xFinal,
64 G4int iterationNumber);
65
66 G4double MidPoint(G4double xInitial, G4double xFinal, G4int iterationNumber);
67
68 G4double Gauss(G4double xInitial, G4double xFinal, G4int iterationNumber);
69
70 G4double Simpson(G4double xInitial, G4double xFinal, G4int iterationNumber);
71
72 // Adaptive Gauss integration with accuracy ~ fTolerance
73
74 G4double AdaptGaussIntegration(G4double xInitial, G4double xFinal);
75 // Integrate function from a to be with accuracy <= fTolerance
76
77 protected:
78 G4double Gauss(G4double xInitial, G4double xFinal);
79
80 void AdaptGauss(G4double xInitial, G4double xFinal, G4double& sum,
81 G4int& depth);
82
83 private:
84 function fFunction; // pointer to the function to be integrated
85 G4double fTolerance = 0.0001; // accuracy of integration
86 const G4int fMaxDepth = 100; // constant maximum iteration depth
87 };
88
89 #endif
90