1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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4 | // * * |
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5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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7 | // * conditions of the Geant4 Software License, included in the file * |
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8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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9 | // * include a list of copyright holders. * |
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10 | // * * |
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11 | // * Neither the authors of this software system, nor their employing * |
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12 | // * institutes,nor the agencies providing financial support for this * |
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13 | // * work make any representation or warranty, express or implied, * |
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14 | // * regarding this software system or assume any liability for its * |
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15 | // * use. Please see the license in the file LICENSE and URL above * |
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16 | // * for the full disclaimer and the limitation of liability. * |
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17 | // * * |
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18 | // * This code implementation is the result of the scientific and * |
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19 | // * technical work of the GEANT4 collaboration. * |
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20 | // * By using, copying, modifying or distributing the software (or * |
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21 | // * any work based on the software) you agree to acknowledge its * |
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22 | // * use in resulting scientific publications, and indicate your * |
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23 | // * acceptance of all terms of the Geant4 Software license. * |
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24 | // ******************************************************************** |
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25 | // |
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26 | // |
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27 | // $Id: G4HelixImplicitEuler.cc,v 1.6 2006/06/29 18:24:06 gunter Exp $ |
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28 | // GEANT4 tag $Name: geant4-09-04-beta-01 $ |
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29 | // |
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30 | // |
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31 | // Helix Implicit Euler: |
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32 | // x_1 = x_0 + 1/2 * ( helix(h,t_0,x_0) |
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33 | // + helix(h,t_0+h,x_0+helix(h,t0,x0) ) ) |
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34 | // Second order solver. |
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35 | // Take the current derivative and add it to the current position. |
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36 | // Take the output and its derivative. Add the mean of both derivatives |
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37 | // to form the final output |
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38 | // |
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39 | // W.Wander <wwc@mit.edu> 12/09/97 |
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40 | // |
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41 | // ------------------------------------------------------------------------- |
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42 | |
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43 | #include "G4HelixImplicitEuler.hh" |
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44 | #include "G4ThreeVector.hh" |
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45 | |
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46 | void |
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47 | G4HelixImplicitEuler::DumbStepper( const G4double yIn[], |
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48 | G4ThreeVector Bfld, |
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49 | G4double h, |
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50 | G4double yOut[]) |
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51 | { |
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52 | const G4int nvar = 6 ; |
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53 | G4double yTemp[6], yTemp2[6]; |
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54 | G4ThreeVector Bfld_endpoint; |
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55 | |
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56 | G4int i; |
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57 | |
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58 | // Step forward like in the explicit euler case |
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59 | AdvanceHelix( yIn, Bfld, h, yTemp); |
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60 | |
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61 | // now obtain the new field value at the new point |
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62 | MagFieldEvaluate(yTemp, Bfld_endpoint); |
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63 | |
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64 | // and also advance along a helix for this field value |
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65 | AdvanceHelix( yIn, Bfld_endpoint, h, yTemp2); |
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66 | |
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67 | // we take the average |
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68 | for( i = 0; i < nvar; i++ ) |
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69 | yOut[i] = 0.5 * ( yTemp[i] + yTemp2[i] ); |
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70 | |
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71 | // NormaliseTangentVector( yOut ); |
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72 | } |
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