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geant4/source/geometry/magneticfield/include/G4TQuadrupoleMagField.hh
2025-12-05 08:54:02 +01:00

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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.
// Adapted from G4QuadrupoleMagField.
// Author: Josh Xie (CERN, Google Summer of Code 2014), June 2014
// Supervisors: Sandro Wenzel, John Apostolakis (CERN)
// --------------------------------------------------------------------
#ifndef G4T_QUADRUPOLE_MAGFIELD_HH
#define G4T_QUADRUPOLE_MAGFIELD_HH
#include "G4ThreeVector.hh"
#include "G4RotationMatrix.hh"
#include "G4MagneticField.hh"
/**
* @brief G4TQuadrupoleMagField is a templated version of G4QuadrupoleMagField.
*/
class G4TQuadrupoleMagField : public G4MagneticField
{
public:
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() = default;
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:
static G4RotationMatrix IdentityMatrix;
G4double fGradient;
G4ThreeVector fOrigin;
G4RotationMatrix* fpMatrix;
};
#endif