G4HelixSimpleRunge.cc

Go to the documentation of this file.

//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
// G4HelixSimpleRunge implementation
//
//  Simple Runge:
//        x_1 = x_0 + h * ( dx( t_0+h/2, x_0 + h/2 * dx( t_0, x_0) ) )
//
//  Second order solver.
//  Take the derivative at a position to be assumed at the middle of the
//  Step and add it to the current position.
//
// Author: W. Wander <wwc@mit.edu>, 03.12.1998
// -------------------------------------------------------------------------
 
#include "G4HelixSimpleRunge.hh"
#include "G4ThreeVector.hh"
 
G4HelixSimpleRunge::G4HelixSimpleRunge(G4Mag_EqRhs* EqRhs)
  : G4MagHelicalStepper(EqRhs)
{
}
 
G4HelixSimpleRunge::~G4HelixSimpleRunge()
{
}
 
void
G4HelixSimpleRunge::DumbStepper( const G4double      yIn[],
                                       G4ThreeVector Bfld,
                                       G4double      h,
                                       G4double      yOut[] )
{
  const G4int nvar = 6 ;
  G4double yTemp[nvar];   // , yAdd[nvar];
  G4ThreeVector Bfld_midpoint;
 
  AdvanceHelix( yIn, Bfld, 0.5 * h, yTemp);
  
  // now obtain the new field value at the new point
  //
  MagFieldEvaluate(yTemp, Bfld_midpoint);      
 
  AdvanceHelix( yIn, Bfld_midpoint, h, yOut);
  
  // NormaliseTangentVector( yOut );           
}