include/Geant4/G4TQuadrupoleMagField.hh

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0025 //
0026 // G4TMagFieldEquation
0027 //
0028 // Class description:
0029 //
0030 // Templated version of  motion of quadrupole magnetic field.
0031 // Enables testing of inlined code for field, equation, stepper, driver,
0032 // avoiding all virtual calls.
0033 // Adapted from G4QuadrupoleMagField.
0034
0035 // Author: Josh Xie (CERN, Google Summer of Code 2014), June 2014
0036 // Supervisors:  Sandro Wenzel, John Apostolakis (CERN)
0037 // --------------------------------------------------------------------
0038 #ifndef G4T_QUADRUPOLE_MAGFIELD_HH
0039 #define G4T_QUADRUPOLE_MAGFIELD_HH
0040
0041 #include "G4ThreeVector.hh"
0042 #include "G4RotationMatrix.hh"
0043 #include "G4MagneticField.hh"
0044
0045 /**
0046  * @brief G4TQuadrupoleMagField is a templated version of G4QuadrupoleMagField.
0047  */
0048
0049 class G4TQuadrupoleMagField : public G4MagneticField
0050 {
0051   public:
0052
0053     G4TQuadrupoleMagField(G4double pGradient)
0054     {
0055       fGradient = pGradient ;
0056       fOrigin   = G4ThreeVector( 0.0, 0.0, 0.0) ;
0057       fpMatrix  = &IdentityMatrix;
0058     }
0059
0060     G4TQuadrupoleMagField(G4double pGradient,
0061                           G4ThreeVector pOrigin,
0062                           G4RotationMatrix* pMatrix)
0063     {
0064       fGradient    = pGradient ;
0065       fOrigin      = pOrigin ;
0066       fpMatrix     = pMatrix ;
0067     }
0068
0069     virtual ~G4TQuadrupoleMagField() = default;
0070
0071     inline void GetFieldValue(const G4double y[7],
0072                                     G4double B[3] ) const
0073     {
0074       G4ThreeVector r_global = G4ThreeVector(
0075               y[0] - fOrigin.x(),
0076               y[1] - fOrigin.y(),
0077               y[2] - fOrigin.z());
0078
0079       G4ThreeVector r_local = G4ThreeVector(
0080               fpMatrix->colX() * r_global,
0081               fpMatrix->colY() * r_global,
0082               fpMatrix->colZ() * r_global);
0083
0084       G4ThreeVector B_local = G4ThreeVector(
0085               fGradient * r_local.y(),
0086               fGradient * r_local.x(),
0087               0);
0088
0089       G4ThreeVector B_global = G4ThreeVector(
0090               fpMatrix->inverse().rowX() * B_local,
0091               fpMatrix->inverse().rowY() * B_local,
0092               fpMatrix->inverse().rowZ() * B_local);
0093
0094       B[0] = B_global.x() ;
0095       B[1] = B_global.y() ;
0096       B[2] = B_global.z() ;
0097     }
0098
0099     G4TQuadrupoleMagField* Clone() const
0100     {
0101       //TODO: Can the fpMatrix be shared??
0102       return new G4TQuadrupoleMagField(this->fGradient,
0103                                        this->fOrigin,
0104                                        this->fpMatrix);
0105     }
0106
0107   private:
0108
0109     static G4RotationMatrix IdentityMatrix;
0110
0111     G4double          fGradient;
0112     G4ThreeVector     fOrigin;
0113     G4RotationMatrix* fpMatrix;
0114 };
0115
0116 #endif
0117