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 //
0034 // --------------------------------------------------------------------
0035 // Created: Josh Xie  (Google Summer of Code 2014 )
0036 // Adapted from G4QuadrupoleMagField  ( of June 2014 .... )
0037 //
0038
0039 #ifndef G4T_QUADRUPOLE_MAGFIELD_HH
0040 #define G4T_QUADRUPOLE_MAGFIELD_HH
0041
0042 #include "G4ThreeVector.hh"
0043 #include "G4RotationMatrix.hh"
0044 #include "G4MagneticField.hh"
0045
0046 static G4RotationMatrix IdentityMatrix;
0047
0048 class G4TQuadrupoleMagField : public G4MagneticField
0049 {
0050   public: // with description
0051
0052   G4TQuadrupoleMagField(G4double pGradient)
0053   {
0054     fGradient = pGradient ;
0055     fOrigin   = G4ThreeVector( 0.0, 0.0, 0.0) ;
0056     fpMatrix  = &IdentityMatrix;
0057   }
0058
0059         G4TQuadrupoleMagField(G4double pGradient,
0060                 G4ThreeVector pOrigin,
0061                 G4RotationMatrix* pMatrix)
0062         {
0063             fGradient    = pGradient ;
0064             fOrigin      = pOrigin ;
0065             fpMatrix     = pMatrix ;
0066         }
0067
0068         virtual ~G4TQuadrupoleMagField() {;}
0069
0070         inline void GetFieldValue(const G4double y[7],
0071                 G4double B[3]     ) const
0072         {
0073             G4ThreeVector r_global = G4ThreeVector(
0074                     y[0] - fOrigin.x(),
0075                     y[1] - fOrigin.y(),
0076                     y[2] - fOrigin.z());
0077
0078             G4ThreeVector r_local = G4ThreeVector(
0079                     fpMatrix->colX() * r_global,
0080                     fpMatrix->colY() * r_global,
0081                     fpMatrix->colZ() * r_global);
0082
0083             G4ThreeVector B_local = G4ThreeVector(
0084                     fGradient * r_local.y(),
0085                     fGradient * r_local.x(),
0086                     0);
0087
0088             G4ThreeVector B_global = G4ThreeVector(
0089                     fpMatrix->inverse().rowX() * B_local,
0090                     fpMatrix->inverse().rowY() * B_local,
0091                     fpMatrix->inverse().rowZ() * B_local);
0092
0093             B[0] = B_global.x() ;
0094             B[1] = B_global.y() ;
0095             B[2] = B_global.z() ;
0096         }
0097
0098         G4TQuadrupoleMagField* Clone() const
0099         {
0100             //TODO: Can the fpMatrix be shared??
0101             return new G4TQuadrupoleMagField(this->fGradient,
0102                     this->fOrigin,
0103                     this->fpMatrix);
0104         }
0105
0106     private:
0107
0108         G4double          fGradient;
0109         G4ThreeVector     fOrigin;
0110         G4RotationMatrix* fpMatrix;
0111 };
0112 #endif
0113