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// $Id: G4HelixExplicitEuler.hh,v 1.9 2007/08/21 08:52:00 tnikitin Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
//
// class G4HelixExplicitEuler
//
// Class description:
//
// Helix Explicit Euler: x_1 = x_0 + helix(h)
// with helix(h) being a helix piece of length h.
// A simple approach for solving linear differential equations.
// Take the current derivative and add it to the current position.

// History:
// - Created. W.Wander <wwc@mit.edu>, 12/09/97
// -------------------------------------------------------------------

#ifndef G4HELIXEXPLICITEULER_HH
#define G4HELIXEXPLICITEULER_HH

#include "G4MagHelicalStepper.hh"

class G4HelixExplicitEuler : public G4MagHelicalStepper
{
  public:  // with description

    G4HelixExplicitEuler(G4Mag_EqRhs *EqRhs)
      : G4MagHelicalStepper(EqRhs) {}
 
    ~G4HelixExplicitEuler() {}
   void Stepper( const G4double y[],
                  const G4double*,
                        G4double h,
                        G4double yout[],
                        G4double yerr[]  ); 

   void DumbStepper( const G4double y[],
                           G4ThreeVector  Bfld,
                           G4double       h,
                           G4double       yout[]);
   
  G4double DistChord() const;
  public:  // without description

    // DELETED  RightHandSide( ) !!!!  
    // Replaced by MagFieldEvaluate( const G4double y[], G4double B[] )   
    // in G4HelicalStepper
  
    G4int IntegratorOrder() const { return 1; }
};

#endif /* G4EXPLICITEULER_HH */
