G4ImplicitEuler.hh

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// G4ImplicitEuler
//
// Class description:
//
// Implicit Euler stepper for magnetic field:
//      x_1 = x_0 + h/2 * ( dx(t_0,x_0) + dx(t_0+h,x_0+h*dx(t_0,x_0) ) )
//
// Second order solver.
// Takes the current derivative and add it to the current position.
// Takes the output and its derivative. Adds the mean of both
// derivatives to form the final output.

// Author: W. Wander <wwc@mit.edu>, 12.09.1997
// -------------------------------------------------------------------
#ifndef G4IMPLICITEULER_HH
#define G4IMPLICITEULER_HH

#include "G4MagErrorStepper.hh"

class G4ImplicitEuler : public G4MagErrorStepper
{

  public:  // with description

    G4ImplicitEuler(G4EquationOfMotion* EqRhs, G4int numberOfVariables = 6);
   ~G4ImplicitEuler();

    void  DumbStepper( const G4double y[] ,
                       const G4double dydx[] ,
                             G4double h ,
                             G4double yout[] );

    inline G4int IntegratorOrder() const { return 2; }

  private:

    G4double* dydxTemp = nullptr;
    G4double* yTemp = nullptr;    
      // Temporaries, created to avoid new/delete on every call
};

#endif