include/Geant4/G4BogackiShampine23.hh

0001 //
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0024 // ********************************************************************
0025 //
0026 // G4BogackiShampine23
0027 //
0028 // Class description:
0029 //
0030 //  Bogacki-Shampine - 4 - 3(2) non-FSAL implementation
0031 //
0032 //  An implementation of the embedded RK method from the paper
0033 //  [1] P. Bogacki and L. F. Shampine,
0034 //     "A 3(2) pair of Runge - Kutta formulas"
0035 //     Appl. Math. Lett., vol. 2, no. 4, pp. 321-325, Jan. 1989.
0036 //
0037 //  This version does not utilise the FSAL property of the method,
0038 //  which would allow the reuse of the last derivative in the next step.
0039 //  (Alternative FSAL implementation created with revised interface)
0040
0041 // Created: Somnath Banerjee, Google Summer of Code 2015, 20 May 2015
0042 // Supervision: John Apostolakis, CERN
0043 // --------------------------------------------------------------------
0044 #ifndef G4BOGACKI_SHAMPINE23_HH
0045 #define G4BOGACKI_SHAMPINE23_HH
0046
0047 #include "G4MagIntegratorStepper.hh"
0048 #include "G4FieldTrack.hh"
0049
0050 class G4BogackiShampine23 : public G4MagIntegratorStepper
0051 {
0052   public:
0053
0054     G4BogackiShampine23(G4EquationOfMotion* EqRhs,
0055                         G4int numberOfVariables = 6);
0056
0057     void Stepper(const G4double yInput[],
0058                  const G4double dydx[],
0059                        G4double hstep,
0060                        G4double yOutput[],
0061                        G4double yError[]) override;
0062
0063     void Stepper(const G4double yInput[],
0064                  const G4double dydx[],
0065                        G4double hstep,
0066                        G4double yOutput[],
0067                        G4double yError[],
0068                        G4double dydxOutput[]);
0069
0070     G4BogackiShampine23(const G4BogackiShampine23&) = delete;
0071     G4BogackiShampine23& operator = (const G4BogackiShampine23&) = delete;
0072
0073     G4double DistChord() const override;
0074     G4int IntegratorOrder() const  override { return 3; }
0075
0076   private:
0077
0078     void makeStep(const G4double yInput[],
0079                   const G4double dydx[],
0080                   const G4double hstep,
0081                         G4double yOutput[],
0082                         G4double* dydxOutput = nullptr,
0083                         G4double* yError = nullptr) const;
0084
0085     G4double fyIn[G4FieldTrack::ncompSVEC],
0086              fdydx[G4FieldTrack::ncompSVEC],
0087              fyOut[G4FieldTrack::ncompSVEC],
0088              fdydxOut[G4FieldTrack::ncompSVEC];
0089     G4double fhstep = -1.0;
0090 };
0091
0092 #endif