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//
//  Bogacki-Shampine - 8 - 5(4) FSAL implementation by Somnath Banerjee
//  Supervision / code review: John Apostolakis
//
// Sponsored by Google in Google Summer of Code 2015.
// 
//  History
// -----------------------------
//  Created by Somnath Banerjee on 26 May 2015
//  Fixes:
//    J. Apostolakis - June 2017: Coverity issues
//    J. Apostolakis - July 2017: Initialise bi coefficients only once.
////////////////////////////////////////////////////////////////////////

#ifndef G4FSAL_Bogacki_Shampine_45_hh
#define G4FSAL_Bogacki_Shampine_45_hh

#include "G4VFSALIntegrationStepper.hh"

class G4FSALBogackiShampine45 : public G4VFSALIntegrationStepper
{
public:
    G4FSALBogackiShampine45(G4EquationOfMotion *EqRhs,
                     G4int numberOfVariables = 6,
                     G4bool primary =  true);
    ~G4FSALBogackiShampine45();
    
    void Stepper( const G4double y[],
                  const G4double dydx[],
              	   		G4double h,
                	 	G4double yout[],
                 		G4double yerr[],
                 		G4double nextDydx[]) ;
    
    void interpolate( const G4double yInput[],
                      const G4double dydx[],
                            G4double yOut[],
                            G4double Step,
                            G4double tau ) ;
    
    
    G4double  DistChord()   const;
    G4int IntegratorOrder() const { return 4; }
    
  private :
    
    G4FSALBogackiShampine45(const G4FSALBogackiShampine45&) = delete;
    G4FSALBogackiShampine45& operator=(const G4FSALBogackiShampine45&) = delete;
    void PrepareConstants(); 
   
   // Working arrays -- used during stepping
    G4double *ak2, *ak3, *ak4, *ak5, *ak6, *ak7, *ak8, *ak9, *ak10, *ak11,
       *DyDx, *yTemp, *yIn;
    G4double *pseudoDydx_for_DistChord;

    G4double fLastStepLength;
    G4double *fLastInitialVector, *fLastFinalVector,
             *fLastDyDx, *fMidVector, *fMidError;
    // for DistChord calculations

    G4double b[12];     // Working array for interpolation
   
    G4FSALBogackiShampine45* fAuxStepper;

    static bool     fPreparedConstants;
    // Class constants
    static G4double bi[12][7];
};

#endif /* defined( G4FSAL_Bogacki_Shampine_45_hh ) */