// This code implementation is the intellectual property of
// the GEANT4 collaboration.
//
// By copying, distributing or modifying the Program (or any work
// based on the Program) you indicate your acceptance of this statement,
// and all its terms.
//
// $Id: G4SimpleHeum.hh,v 1.3 2000/04/27 09:14:06 gcosmo Exp $
// GEANT4 tag $Name: geant4-02-00 $
//
//
// class G4SimpleHeum
//
// Class description:
//
// Simple Heum:
//        x_1 = x_0  +
//              h * 1/4 * dx(t0,x0)  +
//                  3/4 * dx(t0+2/3*h, x0+2/3*h*(dx(t0+h/3,x0+h/3*dx(t0,x0)))) 
//
// third order solver.

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

#ifndef G4SIMPLEHEUM_HH
#define G4SIMPLEHEUM_HH

#include "G4MagErrorStepper.hh"

class G4SimpleHeum : public G4MagErrorStepper
{

  public:  // with description

    G4SimpleHeum(G4Mag_EqRhs *EqRhs, G4int num_variables=6);
   ~G4SimpleHeum();
      // Constructor and destructor.

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

  public:  // without description
  
    G4int IntegratorOrder() { return 3; }

  private:

    const G4int fNumberOfVariables;

    G4double* dydxTemp  ;
    G4double* dydxTemp2 ;
    G4double* yTemp     ;
    G4double* yTemp2    ;
      // scratch space    
};

#endif /* G4SIMPLEHEUM_HH */
