File Propagator.hpp

namespace Acts

Note

This file is foreseen for the Geometry module to replace Extent

template<typename stepper_t, typename navigator_t = detail::VoidNavigator>
class Propagator
#include <Acts/Propagator/Propagator.hpp>

Propagator for particles (optionally in a magnetic field)

The Propagator works with a state objects given at function call This state object contains the thread local state objects

  • Navigator::state_type for object navigation and screen output

  • Stepper::state_type state for the actual transport caching (pos,dir,field)

This Propagator class serves as high-level steering code for propagating track parameters. The actual implementation of the propagation has to be implemented in the stepper_t object, which has to provide the following:

  • a function for performing a single propagation step

  • a type mapping for: initial track parameter type -> type of final track parameters

  • a type mapping for: (initial track parameter type and destination surface type) -> type of final track parameters

  • a type mapping for: initial track parameter type -> type of internal state object

  • a type mapping for: (initial track parameter type and destination surface type) -> type of internal state object

Template Parameters
  • stepper_t – Type of stepper implementation of the propagation

  • naviagor_t – Type of the navigator (optional)

Public Types

using action_list_t_result_t = typename result_type_helper<parameters_t, action_list_t>::type

Short-hand type definition for propagation result derived from an action list.

Template Parameters
  • parameters_t – Type of the final track parameters

  • action_list_t – List of propagation action types

using Navigator = navigator_t

Type of the navigator in use for public scope.

using NavigatorState = typename navigator_t::State

Typedef the navigator state.

using Stepper = stepper_t

Type of the stepper in use for public scope.

using StepperState = typename Stepper::State

Type of state object used by the propagation implementation.

Public Functions

inline explicit Propagator(stepper_t stepper, navigator_t navigator = navigator_t())

Constructor from implementation object.

Parameters
  • stepper – The stepper implementation is moved to a private member

  • navigator – The navigator implementation, moved to a private member

template<typename parameters_t, typename propagator_options_t, typename path_aborter_t = PathLimitReached>
Result<action_list_t_result_t<CurvilinearTrackParameters, typename propagator_options_t::action_list_type>> propagate(const parameters_t &start, const propagator_options_t &options) const

Propagate track parameters.

This function performs the propagation of the track parameters using the internal stepper implementation, until at least one abort condition is fulfilled or the maximum number of steps/path length provided in the propagation options is reached.

Template Parameters
  • parameters_t – Type of initial track parameters to propagate

  • propagator_options_t – Type of the propagator options

  • path_aborter_t – The path aborter type to be added

Parameters
  • start[in] initial track parameters to propagate

  • options[in] Propagation options, type Options<,>

Returns

Propagation result containing the propagation status, final track parameters, and output of actions (if they produce any)

template<typename parameters_t, typename propagator_options_t, typename path_aborter_t = PathLimitReached>
Result<action_list_t_result_t<CurvilinearTrackParameters, typename propagator_options_t::action_list_type>> propagate(const parameters_t &start, const propagator_options_t &options, action_list_t_result_t<CurvilinearTrackParameters, typename propagator_options_t::action_list_type> &&inputResult) const

Propagate track parameters.

This function performs the propagation of the track parameters using the internal stepper implementation, until at least one abort condition is fulfilled or the maximum number of steps/path length provided in the propagation options is reached.

Template Parameters
  • parameters_t – Type of initial track parameters to propagate

  • propagator_options_t – Type of the propagator options

  • path_aborter_t – The path aborter type to be added

Parameters
  • start[in] initial track parameters to propagate

  • options[in] Propagation options, type Options<,>

  • inputResult[in] an existing result object to start from

Returns

Propagation result containing the propagation status, final track parameters, and output of actions (if they produce any)

template<typename parameters_t, typename propagator_options_t, typename target_aborter_t = SurfaceReached, typename path_aborter_t = PathLimitReached>
Result<action_list_t_result_t<BoundTrackParameters, typename propagator_options_t::action_list_type>> propagate(const parameters_t &start, const Surface &target, const propagator_options_t &options) const

Propagate track parameters - User method.

This function performs the propagation of the track parameters according to the internal implementation object until at least one abort condition is fulfilled, the destination surface is hit or the maximum number of steps/path length as given in the propagation options is reached.

Template Parameters
  • parameters_t – Type of initial track parameters to propagate

  • propagator_options_t – Type of the propagator options

  • target_aborter_t – The target aborter type to be added

  • path_aborter_t – The path aborter type to be added

Parameters
  • start[in] Initial track parameters to propagate

  • target[in] Target surface of to propagate to

  • options[in] Propagation options

Returns

Propagation result containing the propagation status, final track parameters, and output of actions (if they produce any)

template<typename parameters_t, typename propagator_options_t, typename target_aborter_t = SurfaceReached, typename path_aborter_t = PathLimitReached>
Result<action_list_t_result_t<BoundTrackParameters, typename propagator_options_t::action_list_type>> propagate(const parameters_t &start, const Surface &target, const propagator_options_t &options, action_list_t_result_t<BoundTrackParameters, typename propagator_options_t::action_list_type> inputResult) const

Propagate track parameters - User method.

This function performs the propagation of the track parameters according to the internal implementation object until at least one abort condition is fulfilled, the destination surface is hit or the maximum number of steps/path length as given in the propagation options is reached.

Template Parameters
  • parameters_t – Type of initial track parameters to propagate

  • propagator_options_t – Type of the propagator options

  • target_aborter_t – The target aborter type to be added

  • path_aborter_t – The path aborter type to be added

Parameters
  • start[in] Initial track parameters to propagate

  • target[in] Target surface of to propagate to

  • options[in] Propagation options

  • inputResult[in] an existing result object to start from

Returns

Propagation result containing the propagation status, final track parameters, and output of actions (if they produce any)

Private Types

using BoundState = std::tuple<BoundTrackParameters, Jacobian, double>
using CurvilinearState = std::tuple<CurvilinearTrackParameters, Jacobian, double>
using Jacobian = BoundMatrix

Private Functions

template<typename result_t, typename propagator_state_t>
Result<void> propagate_impl(propagator_state_t &state, result_t &result) const

Propagate track parameters Private method with propagator and stepper state.

This function performs the propagation of the track parameters according to the internal implementation object until at least one abort condition is fulfilled, the destination surface is hit or the maximum number of steps/path length as given in the propagation options is reached.

Note

Does not (yet) convert into the return_type of the propagation

Template Parameters
  • result_t – Type of the result object for this propagation

  • propagator_state_t – Type of the propagator state with options

Parameters
  • state[inout] the propagator state object

  • result[inout] an existing result object to start from

Returns

Propagation result

Private Members

navigator_t m_navigator

Implementation of navigator.

stepper_t m_stepper

Implementation of propagation algorithm.

template<typename parameters_t, typename action_list_t>
struct result_type_helper

Helper struct determining the result’s type.

This helper struct provides type definitions to extract the correct propagation result type from a given TrackParameter type and an ActionList.

Template Parameters
  • parameters_t – Type of final track parameters

  • action_list_t – List of propagation action types

Public Types

using this_result_type = PropagatorResult<parameters_t, args...>

Propagation result type for an arbitrary list of additional propagation results.

Template Parameters

args – Parameter pack specifying additional propagation results

using type = typename action_list_t::template result_type<this_result_type>

Propagation result type derived from a given action list.

template<typename propagator_options_t>
struct State
#include <Acts/Propagator/Propagator.hpp>

private Propagator state for navigation and debugging

This struct holds the common state information for propagating which is independent of the actual stepper implementation.

Template Parameters
  • parameters_t – Type of the track parameters

  • propagator_options_t – Type of the Objections object

Public Functions

template<typename parameters_t>
inline State(const parameters_t &start, const propagator_options_t &topts, StepperState steppingIn)

Create the propagator state from the options.

Template Parameters
  • parameters_t – the type of the start parameters

  • propagator_options_t – the type of the propagator options

Parameters
  • start – The start parameters, used to initialize stepping state

  • topts – The options handed over by the propagate call

  • steppingIn – Stepper state instance to begin with

Public Members

std::reference_wrapper<const GeometryContext> geoContext

Context object for the geometry.

NavigatorState navigation

Navigation state - internal state of the Navigator.

propagator_options_t options

These are the options - provided for each propagation step.

StepperState stepping

Stepper state - internal state of the Stepper.

template<typename action_list_t = ActionList<>, typename aborter_list_t = AbortList<>>
struct PropagatorOptions : public Acts::PropagatorPlainOptions
#include <Acts/Propagator/Propagator.hpp>

Options for propagate() call.

Template Parameters
  • action_list_t – List of action types called after each propagation step with the current propagation and stepper state

  • aborter_list_t – List of abort conditions tested after each propagation step using the current propagation and stepper state

Subclassed by Acts::DenseStepperPropagatorOptions< action_list_t, aborter_list_t >

Public Types

using aborter_list_type = aborter_list_t
using action_list_type = action_list_t

Public Functions

PropagatorOptions() = delete

Delete default contructor.

PropagatorOptions(const PropagatorOptions<action_list_t, aborter_list_t> &po) = default

PropagatorOptions copy constructor.

inline PropagatorOptions(const GeometryContext &gctx, const MagneticFieldContext &mctx, LoggerWrapper logger_)

PropagatorOptions with context.

template<typename extended_aborter_list_t>
inline PropagatorOptions<action_list_t, extended_aborter_list_t> extend(extended_aborter_list_t aborters) const

Expand the Options with extended aborters.

Template Parameters

extended_aborter_list_t – Type of the new aborter list

Parameters

aborters – The new aborter list to be used (internally)

inline void setPlainOptions(const PropagatorPlainOptions &pOptions)

Set the plain options.

Parameters

pOptions – The plain options

Public Members

aborter_list_t abortList

List of abort conditions.

action_list_t actionList

List of actions.

std::reference_wrapper<const GeometryContext> geoContext

The context object for the geometry.

LoggerWrapper logger
std::reference_wrapper<const MagneticFieldContext> magFieldContext

The context object for the magnetic field.

struct PropagatorPlainOptions
#include <Acts/Propagator/Propagator.hpp>

Class holding the trivial options in propagator options.

Subclassed by Acts::PropagatorOptions< action_list_t, aborter_list_t >

Public Members

int absPdgCode = 211

The |pdg| code for (eventual) material integration - pion default.

NavigationDirection direction = NavigationDirection::Forward

Propagation direction.

double loopFraction = 0.5

Allowed loop fraction, 1 is a full loop.

bool loopProtection = true

Loop protection step, it adapts the pathLimit.

double mass = 139.57018 * UnitConstants::MeV

The mass for the particle for (eventual) material integration.

unsigned int maxRungeKuttaStepTrials = 10000

Maximum number of Runge-Kutta steps for the stepper step call.

unsigned int maxSteps = 1000

Maximum number of steps for one propagate call.

double maxStepSize = std::numeric_limits<double>::max()

Absolute maximum step size.

double pathLimit = std::numeric_limits<double>::max()

Absolute maximum path length.

double stepSizeCutOff = 0.

Cut-off value for the step size.

double targetTolerance = s_onSurfaceTolerance

Required tolerance to reach target (surface, pathlength)

double tolerance = 1e-4

Tolerance for the error of the integration.

template<typename parameters_t, typename ...result_list>
struct PropagatorResult : private detail::Extendable<result_list...>
#include <Acts/Propagator/Propagator.hpp>

Simple class holding result of propagation call.

Template Parameters
  • parameters_t – Type of final track parameters

  • result_list – Result pack for additional propagation quantities

Public Members

std::unique_ptr<parameters_t> endParameters = nullptr

Final track parameters - initialized to null pointer.

double pathLength = 0.

Signed distance over which the parameters were propagated.

unsigned int steps = 0

Number of propagation steps that were carried out.

std::unique_ptr<BoundMatrix> transportJacobian = nullptr

Full transport jacobian.