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: G4Field.hh,v 1.10 2006/06/29 18:22:13 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 | // |
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31 | // class G4Field |
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32 | // |
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33 | // Class description: |
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34 | // |
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35 | // Abstract class for any kind of Field. |
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36 | // It allows any kind of field (vector, scalar, tensor and any set of them) |
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37 | // to be defined by implementing the inquiry function interface. |
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38 | // |
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39 | // The key method is GetFieldValue( const double Point[4], |
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40 | // ************* double *fieldArr ) |
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41 | // Given an input position/time vector 'Point', |
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42 | // this method must return the value of the field in "fieldArr". |
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43 | // |
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44 | // A field must also specify whether it changes a track's energy: |
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45 | // DoesFieldChangeEnergy() |
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46 | // ********************* |
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47 | // A field must co-work with a corresponding Equation of Motion, to |
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48 | // enable the integration of a particle's position, momentum and, optionally, |
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49 | // spin. For this a field and its equation of motion must follow the |
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50 | // same convention for the order of field components in the array "fieldArr" |
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51 | // ------------------------------------------------------------------- |
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52 | // History: |
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53 | // - Created: John Apostolakis, 10.03.1997 |
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54 | // - Modified: |
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55 | // V. Grichine 8 Nov 2001: Extended "Point" arg to [4] array to add time |
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56 | // J. Apostolakis 5 Nov 2003: Added virtual method DoesFieldChangeEnergy() |
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57 | // J. Apostolakis 31 Aug 2004: Information on convention for components |
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58 | // ------------------------------------------------------------------- |
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59 | |
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60 | #ifndef G4FIELD_HH |
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61 | #define G4FIELD_HH |
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62 | |
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63 | #include "G4Types.hh" |
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64 | |
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65 | class G4Field |
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66 | { |
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67 | public: // with description |
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68 | |
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69 | virtual void GetFieldValue( const double Point[4], |
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70 | double *fieldArr ) const = 0; |
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71 | // Given the position time vector 'Point', |
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72 | // return the value of the field in the array fieldArr. |
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73 | // Notes: |
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74 | // 1) The 'Point' vector has the following structure: |
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75 | // Point[0] is x ( position, in Geant4 units ) |
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76 | // Point[1] is y |
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77 | // Point[2] is z |
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78 | // Point[3] is t ( time, in Geant4 units ) |
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79 | // 2) The convention for the components of the field |
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80 | // array 'fieldArr' are determined by the type of field. |
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81 | // See for example the class G4ElectroMagneticField. |
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82 | |
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83 | G4Field(){;} |
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84 | virtual ~G4Field(){;} |
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85 | inline G4Field& operator = (const G4Field &p); |
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86 | |
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87 | // A field signature function that can be used to insure |
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88 | // that the Equation of motion object and the G4Field object |
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89 | // have the same "field signature"? |
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90 | |
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91 | virtual G4bool DoesFieldChangeEnergy() const= 0 ; |
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92 | // Each type/class of field should respond this accordingly |
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93 | // For example: |
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94 | // - an electric field should return "true" |
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95 | // - a pure magnetic field should return "false" |
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96 | |
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97 | }; |
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98 | |
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99 | inline G4Field& G4Field::operator = (const G4Field &p) |
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100 | { |
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101 | if (&p != this) { *this = p; } |
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102 | return *this; |
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103 | } |
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104 | |
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105 | #endif /* G4FIELD_HH */ |
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