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geant4/source/geometry/magneticfield/include/G4QSStepper.icc
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Gabriele Cosmo b4a16de652 Import Geant4 11.4.0 source tree
2025-12-05 08:54:02 +01:00

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//
// ********************************************************************
// * License and Disclaimer *
// * *
// * The Geant4 software is copyright of the Copyright Holders of *
// * the Geant4 Collaboration. It is provided under the terms and *
// * conditions of the Geant4 Software License, included in the file *
// * LICENSE and available at http://cern.ch/geant4/license . These *
// * include a list of copyright holders. *
// * *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work make any representation or warranty, express or implied, *
// * regarding this software system or assume any liability for its *
// * use. Please see the license in the file LICENSE and URL above *
// * for the full disclaimer and the limitation of liability. *
// * *
// * This code implementation is the result of the scientific and *
// * technical work of the GEANT4 collaboration. *
// * By using, copying, modifying or distributing the software (or *
// * any work based on the software) you agree to acknowledge its *
// * use in resulting scientific publications, and indicate your *
// * acceptance of all terms of the Geant4 Software license. *
// ********************************************************************
//
// G4QSStepper inline methods implementation
//
// Authors: version 1 - Lucio Santi, Rodrigo Castro (Univ. Buenos Aires), 2018-2021
// version 2 - Mattias Portnoy (Univ. Buenos Aires), 2024
// ----------------------------------------------------------------------------
inline
constexpr G4double G4QSStepper::Cubic_Function(const QSStateVector* states,
G4int index, G4double delta_t)
{
return states[DERIVATIVE_0][index] + (states[DERIVATIVE_1][index] + states[DERIVATIVE_2][index] * delta_t / 2 + states[DERIVATIVE_3][index] * delta_t * delta_t / 6) * delta_t;
}
// ----------------------------------------------------------------------------
inline
constexpr G4double G4QSStepper::Parabolic_Function(const QSStateVector* states,
G4int index, G4double delta_t)
{
return states[DERIVATIVE_0][index] + (states[DERIVATIVE_1][index] + states[DERIVATIVE_2][index] * delta_t / 2) * delta_t;
}
// ----------------------------------------------------------------------------
inline
constexpr G4double G4QSStepper::Linear_Function(const QSStateVector* states,
G4int index, G4double delta_t)
{
return states[DERIVATIVE_0][index] + states[DERIVATIVE_1][index] * delta_t;
}
// ----------------------------------------------------------------------------
inline
constexpr G4int G4QSStepper::INDEX_TYPE(G4int i)
{
return i >> 2;
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::momentum_to_velocity(const G4double* momentum, G4double* out)
{
out[0] = momentum[0] * fInv_mass_over_c;
out[1] = momentum[1] * fInv_mass_over_c;
out[2] = momentum[2] * fInv_mass_over_c;
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::compare_time_and_update(G4int& index, G4int i)
{
if (current_substep.sync_t[i] < current_substep.sync_t[index]) { index = i;}
}
// ----------------------------------------------------------------------------
inline
G4int G4QSStepper::IntegratorOrder() const
{
return qss_order;
}
// ----------------------------------------------------------------------------
inline
G4EquationOfMotion* G4QSStepper::GetSpecificEquation()
{
return GetEquationOfMotion();
}
// ----------------------------------------------------------------------------
inline
const field_utils::State& G4QSStepper::GetYOut() const
{
return fYout;
}
// ----------------------------------------------------------------------------
inline
G4double G4QSStepper::DistChord() const
{
return 0.;
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::Stepper(const G4double yInput[],
const G4double dydx[], G4double hstep,
G4double yOutput[], G4double yError[], G4double /*dydxOutput*/ [])
{
Stepper(yInput, dydx, hstep, yOutput, yError);
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::SetupInterpolation()
{
}
inline
void G4QSStepper::reset(const G4FieldTrack *track)
{
fTrack_changed = true; //// Cannot rely on addresses --- OLD was track != fCurrent_track;
fCurrent_track = track;
setRestMass(track->GetRestMass());
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::setRestMass(G4double restMass)
{
if( restMass > 0.0 ){
fRestMass = restMass;
} else {
fRestMass = 1.0e-10 * CLHEP::electronvolt;
#ifdef G4DEBUG_FIELD
G4cerr << "G4QSStepper::setRestMass(): WARNING: Rest Mass (track) = " << restMass << " Reset to:" << fRestMass / CLHEP::eV << " eV " << G4endl;
#endif
}
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::SetPrecision(G4double dq_rel, G4double dq_min)
{
dqmin[0] = dq_min;
dqmin[1] = dq_min;
dqrel[0] = dq_rel;
dqrel[1] = dq_rel;
}
// ----------------------------------------------------------------------------
inline
G4double G4QSStepper::GetLastStepLength()
{
return current_substep.t * fVelocity;
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::velocity_to_momentum(G4double *y)
{
y[3] *= fMassOverC;
y[4] *= fMassOverC;
y[5] *= fMassOverC;
}
// ----------------------------------------------------------------------------
inline
G4int G4QSStepper::get_next_sync_index()
{
// Goes through each index and get the one with the closest sync t.
// Unrolled loop for tiny speedup.
G4int index = 0;
compare_time_and_update(index,1);
compare_time_and_update(index,2);
compare_time_and_update(index,3);
compare_time_and_update(index,4);
compare_time_and_update(index,5);
return index;
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::update_field()
{
G4double old_field[3] = { current_substep.b_field[0],
current_substep.b_field[1],
current_substep.b_field[2] };
GetEquationOfMotion()->GetFieldValue(current_substep.state_x[DERIVATIVE_0],
current_substep.b_field );
fField_changed = false;
for (G4int i = 0; i < 3 && ! fField_changed; ++i)
{
fField_changed = fField_changed || old_field[i] != current_substep.b_field[i];
}
}
// ----------------------------------------------------------------------------
inline
G4double G4QSStepper::extrapolate_polynomial(QSStateVector* states,
G4int index, G4double delta_t, G4int order)
{
if (delta_t == 0 || order == 0) { return states[DERIVATIVE_0][index]; }
switch (order)
{
case 2:
return Parabolic_Function(states,index,delta_t);
break;
case 3:
return Cubic_Function(states,index,delta_t);
break;
case 1:
return Linear_Function(states,index,delta_t);
break;
default:
// TODO check how to raise error
return 146546;
}
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::extrapolate_all_states_to_t(Substep* substep,
G4double t, G4double* yOut)
{
for (G4int j = 0; j < 6; ++j)
{
G4double t_j = substep->state_tx[j];
G4double delta_tj = t - t_j;
yOut[j] = extrapolate_polynomial(&substep->state_x[DERIVATIVE_0], j, delta_tj, substep->extrapolation_method);
}
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::update_x(G4int index, G4double t)
{
G4double delta_t = t - current_substep.state_tx[index];
if (delta_t == 0) { return; }
//current_substep.state_x[DERIVATE_1][index] += current_substep.state_x[DERIVATE_2][index] * delta_t;
switch (qss_order)
{
case 2:
current_substep.state_x[DERIVATIVE_0][index] = Parabolic_Function(current_substep.state_x,index,delta_t);
current_substep.state_x[DERIVATIVE_1][index] = Linear_Function((&current_substep.state_x[DERIVATIVE_1]),index,delta_t);
break;
case 3:
current_substep.state_x[DERIVATIVE_0][index] = Cubic_Function(current_substep.state_x,index,delta_t);
current_substep.state_x[DERIVATIVE_1][index] = Parabolic_Function((&current_substep.state_x[DERIVATIVE_1]),index,delta_t);
current_substep.state_x[DERIVATIVE_2][index] = Linear_Function((&current_substep.state_x[DERIVATIVE_2]),index,delta_t);
break;
case 1:
current_substep.state_x[DERIVATIVE_0][index] = Linear_Function(current_substep.state_x,index,delta_t);
break;
default:
break;
}
current_substep.state_tx[index] = t;
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::update_q(G4int index, G4double t)
{
G4double delta_t = t - current_substep.state_tq[index];
if (delta_t == 0) { return; }
switch (qss_order)
{
case 2:
current_substep.state_q[DERIVATIVE_0][index] = Linear_Function(current_substep.state_q,index,delta_t);
break;
case 3:
current_substep.state_q[DERIVATIVE_0][index] = Parabolic_Function(current_substep.state_q,index,delta_t);
current_substep.state_q[DERIVATIVE_1][index] = Linear_Function((&current_substep.state_q[DERIVATIVE_1]),index,delta_t);
break;
case 1:
break;
}
current_substep.state_tq[index] = t;
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::update_x_position_derivates_using_q(G4int index)
{
// assumes index is position index
current_substep.state_x[DERIVATIVE_1][index] =
current_substep.state_q[DERIVATIVE_0][index+VELOCITY_IDX];
current_substep.state_x[DERIVATIVE_2][index] =
current_substep.state_q[DERIVATIVE_1][index+VELOCITY_IDX];
current_substep.state_x[DERIVATIVE_3][index] =
current_substep.state_q[DERIVATIVE_2][index+VELOCITY_IDX];
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::update_x_velocity_derivates_using_q(G4int index)
{
// asumes index is velocity index
G4int modulo = VELOCITY_IDX;
G4int index_pos = (index+modulo+1)%modulo;
G4int index_neg = (index+modulo-1)%modulo;
G4double b1 = current_substep.b_field[index_pos];
G4double b2 = current_substep.b_field[index_neg];
for (G4int derivate_order = 0; derivate_order < qss_order; ++derivate_order)
{
current_substep.state_x[derivate_order+1][index] =
fCoeff* (
current_substep.state_q[derivate_order][index_pos+VELOCITY_IDX] * b2 -
current_substep.state_q[derivate_order][index_neg+VELOCITY_IDX] * b1
);
}
}
// ----------------------------------------------------------------------------
inline
void G4QSStepper::update_x_derivates_using_q(G4int index)
{
// updates x using q with the Lorentz equation
if (index < VELOCITY_IDX)
{
update_x_position_derivates_using_q(index);
}
else
{
update_x_velocity_derivates_using_q(index);
}
}
// ----------------------------------------------------------------------------
/* Updates when does the x,q distance goes beyond the quantum.
For the special case of both polynomials being equal except
for higher coefficient- Such as after syncing */
inline
void G4QSStepper::update_sync_time_one_coefficient(G4int index)
{
G4double leading_poly_cofficient = current_substep.state_x[qss_order][index];
if (leading_poly_cofficient == 0)
{
current_substep.sync_t[index] = INFTY;
}
else
{
G4double dq_leading_ratio = dq_vector[index]/std::fabs(leading_poly_cofficient);
switch (qss_order)
{
case 2:
current_substep.sync_t[index] = current_substep.state_tx[index] + std::sqrt(dq_leading_ratio);
break;
case 3:
current_substep.sync_t[index] = current_substep.state_tx[index] + cbrt(dq_leading_ratio);
break;
case 1:
current_substep.sync_t[index] = current_substep.state_tx[index] + dq_leading_ratio;
break;
}
}
}
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