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G4ClassicalRK4.hh
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25 //
26 // G4ClassicalRK4
27 //
28 // Class description:
29 //
30 // Integrate the equations of the motion of a particle in a magnetic field
31 // using the classical 4th Runge-Kutta method.
32 
33 // Created: J.Apostolakis, V.Grichine - 30.01.1997
34 // -------------------------------------------------------------------
35 #ifndef G4CLASSICALRK4_HH
36 #define G4CLASSICALRK4_HH
37 
38 #include "G4MagErrorStepper.hh"
39 
41 {
42  public: // with description
43 
44  G4ClassicalRK4(G4EquationOfMotion* EquationMotion,
45  G4int numberOfVariables = 6) ;
46 
47  ~G4ClassicalRK4() ;
48 
49  G4ClassicalRK4(const G4ClassicalRK4&) = delete;
50  G4ClassicalRK4& operator=(const G4ClassicalRK4&) = delete;
51  // Copy constructor and assignment operator not allowed.
52 
53  // A stepper that does not know about errors.
54  // It is used by the MagErrorStepper stepper.
55 
56  void DumbStepper( const G4double yIn[],
57  const G4double dydx[],
58  G4double h,
59  G4double yOut[] ) ;
60  // Given values for the variables y[0,..,n-1] and their derivatives
61  // dydx[0,...,n-1] known at x, use the classical 4th Runge-Kutta
62  // method to advance the solution over an interval h and return the
63  // incremented variables as yout[0,...,n-1], which not be a distinct
64  // array from y. The user supplies the routine RightHandSide(x,y,dydx),
65  // which returns derivatives dydx at x. The source is routine rk4 from
66  // NRC p. 712-713 .
67 
68  public: // without description
69 
70  G4int IntegratorOrder() const { return 4; }
71 
72  private:
73 
74  void StepWithEst( const G4double yIn[],
75  const G4double dydx[],
76  G4double h,
77  G4double yOut[],
78  G4double& alpha2,
79  G4double& beta2,
80  const G4double B1[],
81  G4double B2[] );
82  // No longer used. Obsolete.
83 
84  private:
85 
86  // G4int fNumberOfVariables ; // is set default to 6 in constructor
87 
88  G4double *dydxm, *dydxt, *yt; // scratch space - not state
89 };
90 
91 #endif