G4TQuadrupoleMagField.hh

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// G4TMagFieldEquation
//
// Class description:
//
// Templated version of  motion of quadrupole magnetic field.
// Enables testing of inlined code for field, equation, stepper, driver,
// avoiding all virtual calls.
//
// --------------------------------------------------------------------
// Created: Josh Xie  (Google Summer of Code 2014 )
// Adapted from G4QuadrupoleMagField  ( of June 2014 .... )
//
 
#ifndef G4T_QUADRUPOLE_MAGFIELD_HH
#define G4T_QUADRUPOLE_MAGFIELD_HH
 
#include "G4ThreeVector.hh"
#include "G4RotationMatrix.hh"
#include "G4MagneticField.hh"
 
static G4RotationMatrix IdentityMatrix; 
 
class G4TQuadrupoleMagField : public G4MagneticField 
{
  public: // with description
 
  G4TQuadrupoleMagField(G4double pGradient)
  {
    fGradient = pGradient ;
    fOrigin   = G4ThreeVector( 0.0, 0.0, 0.0) ;
    fpMatrix  = &IdentityMatrix;
  }
 
        G4TQuadrupoleMagField(G4double pGradient, 
                G4ThreeVector pOrigin, 
                G4RotationMatrix* pMatrix)
        {
            fGradient    = pGradient ;
            fOrigin      = pOrigin ;
            fpMatrix     = pMatrix ;
        }
 
        virtual ~G4TQuadrupoleMagField() {;}
 
        inline void GetFieldValue(const G4double y[7],
                G4double B[3]     ) const
        {
            G4ThreeVector r_global = G4ThreeVector(
                    y[0] - fOrigin.x(), 
                    y[1] - fOrigin.y(), 
                    y[2] - fOrigin.z());
 
            G4ThreeVector r_local = G4ThreeVector(
                    fpMatrix->colX() * r_global,
                    fpMatrix->colY() * r_global,
                    fpMatrix->colZ() * r_global);
 
            G4ThreeVector B_local = G4ThreeVector(
                    fGradient * r_local.y(),
                    fGradient * r_local.x(),
                    0);
 
            G4ThreeVector B_global = G4ThreeVector(
                    fpMatrix->inverse().rowX() * B_local,
                    fpMatrix->inverse().rowY() * B_local,
                    fpMatrix->inverse().rowZ() * B_local);
 
            B[0] = B_global.x() ;
            B[1] = B_global.y() ;
            B[2] = B_global.z() ;
        }
 
        G4TQuadrupoleMagField* Clone() const
        {
            //TODO: Can the fpMatrix be shared??
            return new G4TQuadrupoleMagField(this->fGradient,
                    this->fOrigin,
                    this->fpMatrix);
        }
 
    private:
 
        G4double          fGradient;
        G4ThreeVector     fOrigin;
        G4RotationMatrix* fpMatrix;
};
#endif