00001 // 00002 // ******************************************************************** 00003 // * License and Disclaimer * 00004 // * * 00005 // * The Geant4 software is copyright of the Copyright Holders of * 00006 // * the Geant4 Collaboration. It is provided under the terms and * 00007 // * conditions of the Geant4 Software License, included in the file * 00008 // * LICENSE and available at http://cern.ch/geant4/license . These * 00009 // * include a list of copyright holders. * 00010 // * * 00011 // * Neither the authors of this software system, nor their employing * 00012 // * institutes,nor the agencies providing financial support for this * 00013 // * work make any representation or warranty, express or implied, * 00014 // * regarding this software system or assume any liability for its * 00015 // * use. Please see the license in the file LICENSE and URL above * 00016 // * for the full disclaimer and the limitation of liability. * 00017 // * * 00018 // * This code implementation is the result of the scientific and * 00019 // * technical work of the GEANT4 collaboration. * 00020 // * By using, copying, modifying or distributing the software (or * 00021 // * any work based on the software) you agree to acknowledge its * 00022 // * use in resulting scientific publications, and indicate your * 00023 // * acceptance of all terms of the Geant4 Software license. * 00024 // ******************************************************************** 00025 // 00026 // 00027 // $Id: G4Field.hh 69786 2013-05-15 09:38:51Z gcosmo $ 00028 // 00029 // 00030 // class G4Field 00031 // 00032 // Class description: 00033 // 00034 // Abstract class for any kind of Field. 00035 // It allows any kind of field (vector, scalar, tensor and any set of them) 00036 // to be defined by implementing the inquiry function interface. 00037 // 00038 // The key method is GetFieldValue( const double Point[4], 00039 // ************* double *fieldArr ) 00040 // Given an input position/time vector 'Point', 00041 // this method must return the value of the field in "fieldArr". 00042 // 00043 // A field must also specify whether it changes a track's energy: 00044 // DoesFieldChangeEnergy() 00045 // ********************* 00046 // A field must co-work with a corresponding Equation of Motion, to 00047 // enable the integration of a particle's position, momentum and, optionally, 00048 // spin. For this a field and its equation of motion must follow the 00049 // same convention for the order of field components in the array "fieldArr" 00050 // ------------------------------------------------------------------- 00051 // History: 00052 // - Created: John Apostolakis, 10.03.1997 00053 // - Modified: 00054 // V. Grichine 8 Nov 2001: Extended "Point" arg to [4] array to add time 00055 // J. Apostolakis 5 Nov 2003: Added virtual method DoesFieldChangeEnergy() 00056 // J. Apostolakis 31 Aug 2004: Information on convention for components 00057 // ------------------------------------------------------------------- 00058 00059 #ifndef G4FIELD_HH 00060 #define G4FIELD_HH 00061 00062 #include "G4Types.hh" 00063 00064 class G4Field 00065 { 00066 public: // with description 00067 00068 virtual void GetFieldValue( const double Point[4], 00069 double *fieldArr ) const = 0; 00070 // Given the position time vector 'Point', 00071 // return the value of the field in the array fieldArr. 00072 // Notes: 00073 // 1) The 'Point' vector has the following structure: 00074 // Point[0] is x ( position, in Geant4 units ) 00075 // Point[1] is y 00076 // Point[2] is z 00077 // Point[3] is t ( time, in Geant4 units ) 00078 // 2) The convention for the components of the field 00079 // array 'fieldArr' are determined by the type of field. 00080 // See for example the class G4ElectroMagneticField. 00081 00082 G4Field( G4bool gravityOn= false); 00083 G4Field( const G4Field & ); 00084 virtual ~G4Field(); 00085 inline G4Field& operator = (const G4Field &p); 00086 00087 // A field signature function that can be used to insure 00088 // that the Equation of motion object and the G4Field object 00089 // have the same "field signature"? 00090 00091 virtual G4bool DoesFieldChangeEnergy() const= 0 ; 00092 // Each type/class of field should respond this accordingly 00093 // For example: 00094 // - an electric field should return "true" 00095 // - a pure magnetic field should return "false" 00096 00097 G4bool IsGravityActive() const { return fGravityActive;} 00098 // Does this field include gravity? 00099 inline void SetGravityActive( G4bool OnOffFlag ); 00100 private: 00101 G4bool fGravityActive; 00102 }; 00103 00104 inline void G4Field::SetGravityActive( G4bool OnOffFlag ) 00105 { 00106 fGravityActive= OnOffFlag; 00107 } 00108 #endif /* G4FIELD_HH */