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/// \file field/BlineTracer/src/G4BlineEquation.cc
/// \brief Implementation of the G4BlineEquation class
//
//
// $Id$
//
// 
// --------------------------------------------------------------------
//
// G4BlineEquation implementation
//
// --------------------------------------------------------------------
// Author: Laurent Desorgher (desorgher@phim.unibe.ch)
//         Created - 2003-10-06
// --------------------------------------------------------------------

#include "G4BlineEquation.hh"

///////////////////////////////////////////////////////////////////////////

G4BlineEquation::G4BlineEquation( G4MagneticField* MagField )
  : G4Mag_EqRhs( MagField ) 
{
  fBackward_direction=false;
  fDirection=1.;
}

///////////////////////////////////////////////////////////////////////////

G4BlineEquation::~G4BlineEquation()
{
}

/////////////////////////////////////////////////////////////////////////////

void G4BlineEquation::EvaluateRhsGivenB( const G4double y[],
                                         const G4double B[3],
                                               G4double dydx[] ) const
{
  G4double Bmag = fDirection*std::sqrt(B[0]*B[0] + B[1]*B[1] + B[2]*B[2]);
  dydx[0] = B[0]/Bmag;       
  dydx[1] = B[1]/Bmag;       
  dydx[2] = B[2]/Bmag;

  dydx[3]=0. * y[0]; //y[0] is used to remove warning
  dydx[4]=0.;
  dydx[5]=0.;
}

//////////////////////////////////////////////////////////////////////

void G4BlineEquation::SetBackwardDirectionOfIntegration(G4bool abool)
{
  fBackward_direction=abool;
  fDirection=1.;
  if (fBackward_direction) fDirection= -1.;
}
