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: G4SimpleRunge.cc,v 1.10 2006/06/29 18:24:53 gunter Exp $ |
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28 | // GEANT4 tag $Name: geant4-09-02-cand-01 $ |
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29 | // |
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30 | // Simple Runge: |
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31 | // |
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32 | // x_1 = x_0 + h * ( dx( t_0+h/2, x_0 + h/2 * dx( t_0, x_0) ) ) |
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33 | // |
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34 | // Second order solver. |
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35 | // Takes the derivative at a position to be assumed at the middle of the |
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36 | // Step and adds it to the current position. |
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37 | // |
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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 | #include "G4SimpleRunge.hh" |
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43 | #include "G4ThreeVector.hh" |
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44 | |
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45 | //////////////////////////////////////////////////////////////// |
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46 | // |
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47 | // Constructor |
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48 | |
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49 | G4SimpleRunge::G4SimpleRunge(G4EquationOfMotion* EqRhs, G4int numberOfVariables) |
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50 | : G4MagErrorStepper(EqRhs, numberOfVariables), |
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51 | fNumberOfVariables(numberOfVariables) |
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52 | { |
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53 | |
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54 | unsigned int noVariables= std::max(numberOfVariables, |
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55 | GetNumberOfStateVariables()); |
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56 | // To deal with Time >= 7+1 |
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57 | dydxTemp = new G4double[noVariables] ; |
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58 | yTemp = new G4double[noVariables] ; |
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59 | } |
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60 | |
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61 | |
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62 | ///////////////////////////////////////////////////////////////// |
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63 | // |
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64 | // Destructor |
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65 | |
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66 | G4SimpleRunge::~G4SimpleRunge() |
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67 | { |
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68 | delete[] dydxTemp; |
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69 | delete[] yTemp; |
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70 | } |
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71 | |
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72 | ////////////////////////////////////////////////////////////////// |
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73 | // |
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74 | // |
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75 | |
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76 | void |
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77 | G4SimpleRunge::DumbStepper( const G4double yIn[], |
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78 | const G4double dydx[], |
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79 | G4double h, |
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80 | G4double yOut[]) |
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81 | { |
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82 | // Initialise time to t0, needed when it is not updated by the integration. |
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83 | yTemp[7] = yOut[7] = yIn[7]; // Better to set it to NaN; // TODO |
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84 | |
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85 | G4int i; |
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86 | |
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87 | for( i = 0; i < fNumberOfVariables; i++ ) |
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88 | { |
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89 | yTemp[i] = yIn[i] + 0.5 * h*dydx[i] ; |
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90 | } |
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91 | |
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92 | RightHandSide(yTemp,dydxTemp); |
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93 | |
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94 | for( i = 0; i < fNumberOfVariables; i++ ) |
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95 | { |
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96 | yOut[i] = yIn[i] + h * ( dydxTemp[i] ); |
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97 | } |
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98 | } |
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