Class StraightLineStepper¶
Defined in File StraightLineStepper.hpp
Class Documentation¶
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class
Acts
::
StraightLineStepper
¶ straight line stepper based on Surface intersection
The straight line stepper is a simple navigation stepper to be used to navigate through the tracking geometry. It can be used for simple material mapping, navigation validation
Public Types
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using
BField
= NullBField¶
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using
BoundState
= std::tuple<BoundTrackParameters, Jacobian, double>¶
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using
Covariance
= BoundSymMatrix¶
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using
CurvilinearState
= std::tuple<CurvilinearTrackParameters, Jacobian, double>¶
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using
Jacobian
= BoundMatrix¶
Public Functions
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StraightLineStepper
() = default¶ Constructor.
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BoundState
boundState
(State &state, const Surface &surface) const¶ Create and return the bound state at the current position.
It does not check if the transported state is at the surface, this needs to be guaranteed by the propagator
- Return
A bound state:
the parameters at the surface
the stepwise jacobian towards it (from last bound)
and the path length (from start - for ordering)
- Parameters
[in] state
: State that will be presented asBoundState
[in] surface
: The surface to which we bind the state
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double
charge
(const State &state) const¶ Charge access.
- Parameters
state
: [in] The stepping state (thread-local cache)
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void
covarianceTransport
(State &state) const¶ Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state - for the moment a dummy method.
- Parameters
[inout] state
: State of the stepper
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void
covarianceTransport
(State &state, const Surface &surface) const¶ Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state - for the moment a dummy method.
- Note
no check is done if the position is actually on the surface
- Template Parameters
surface_t
: the surface type - ignored here
- Parameters
[inout] state
: The stepper state[in] surface
: is the surface to which the covariance is forwarded to
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CurvilinearState
curvilinearState
(State &state) const¶ Create and return a curvilinear state at the current position.
This creates a curvilinear state.
- Return
A curvilinear state:
the curvilinear parameters at given position
the stepweise jacobian towards it (from last bound)
and the path length (from start - for ordering)
- Parameters
[in] state
: State that will be presented asCurvilinearState
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Vector3D
direction
(const State &state) const¶ Momentum direction accessor.
- Parameters
state
: [in] The stepping state (thread-local cache)
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Vector3D
getField
(State&, const Vector3D&) const¶ Get the field for the stepping, this gives back a zero field.
- Parameters
[inout] state
: is the propagation state associated with the track the magnetic field cell is used (and potentially updated)[in] pos
: is the field position
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double
momentum
(const State &state) const¶ Momentum accessor.
- Parameters
state
: [in] The stepping state (thread-local cache)
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std::string
outputStepSize
(const State &state) const¶ Output the Step Size - single component.
- Parameters
state
: [in,out] The stepping state (thread-local cache)
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double
overstepLimit
(const State&) const¶ Overstep limit.
- Parameters
state
: The stepping state (thread-local cache)
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Vector3D
position
(const State &state) const¶ Global particle position accessor.
- Parameters
state
: [in] The stepping state (thread-local cache)
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void
releaseStepSize
(State &state) const¶ Release the Step size.
- Parameters
state
: [in,out] The stepping state (thread-local cache)
Resets the state.
- Parameters
[inout] state
: State of the stepper[in] boundParams
: Parameters in bound parametrisation[in] freeParams
: Parameters in free parametrisation[in] cov
: Covariance matrix[in] navDir
: Navigation direction[in] stepSize
: Step size
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void
setStepSize
(State &state, double stepSize, ConstrainedStep::Type stype = ConstrainedStep::actor) const¶ Set Step size - explicitely with a double.
- Parameters
state
: [in,out] The stepping state (thread-local cache)stepSize
: [in] The step size valuestype
: [in] The step size type to be set
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template<typename
propagator_state_t
>
Result<double>step
(propagator_state_t &state) const¶ Perform a straight line propagation step.
- Return
the step size taken
- Parameters
[inout] state
: is the propagation state associated with the track parameters that are being propagated. The state contains the desired step size, it can be negative during backwards track propagation, and since we’re using an adaptive algorithm, it can be modified by the stepper class during propagation.
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double
time
(const State &state) const¶ Time access.
- Parameters
state
: [in] The stepping state (thread-local cache)
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void
update
(State &state, const FreeVector ¶meters, const Covariance &covariance) const¶ Method to update a stepper state to the some parameters.
- Parameters
[inout] state
: State object that will be updated[in] pars
: Parameters that will be written intostate
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void
update
(State &state, const Vector3D &uposition, const Vector3D &udirection, double up, double time) const¶ Method to update momentum, direction and p.
- Parameters
[inout] state
: State object that will be updated[in] uposition
: the updated position[in] udirection
: the updated direction[in] up
: the updated momentum value[in] time
: the updated time value
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template<typename
object_intersection_t
>
voidupdateStepSize
(State &state, const object_intersection_t &oIntersection, bool release = true) const¶ Update step size.
It checks the status to the reference surface & updates the step size accordingly
- Parameters
state
: [in,out] The stepping state (thread-local cache)oIntersection
: [in] The ObjectIntersection to layer, boundary, etcrelease
: [in] boolean to trigger step size release
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Intersection3D::Status
updateSurfaceStatus
(State &state, const Surface &surface, const BoundaryCheck &bcheck) const¶ Update surface status.
This method intersects the provided surface and update the navigation step estimation accordingly (hence it changes the state). It also returns the status of the intersection to trigger onSurface in case the surface is reached.
- Parameters
state
: [in,out] The stepping state (thread-local cache)surface
: [in] The surface providedbcheck
: [in] The boundary check for this status update
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struct
State
¶ State for track parameter propagation.
Public Functions
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State
() = delete¶ Delete the default constructor.
Constructor from the initial track parameters.
- Template Parameters
parameters_t
: the Type of the track parameters
- Parameters
[in] gctx
: is the context object for the geometery[in] mctx
: is the context object for the magnetic field[in] par
: The track parameters at start[in] ndir
: is the navigation direction[in] ssize
: is the (absolute) maximum step size[in] stolerance
: is the stepping tolerance
Public Members
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Covariance
cov
= Covariance::Zero()¶
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bool
covTransport
= false¶ Boolean to indiciate if you need covariance transport.
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FreeVector
derivative
= FreeVector::Zero()¶ The propagation derivative.
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std::reference_wrapper<const GeometryContext>
geoContext
¶
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BoundToFreeMatrix
jacToGlobal
= BoundToFreeMatrix::Zero()¶ Jacobian from local to the global frame.
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FreeMatrix
jacTransport
= FreeMatrix::Identity()¶ Pure transport jacobian part from runge kutta integration.
Navigation direction, this is needed for searching.
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double
p
= 0.¶ Momentum.
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double
pathAccumulated
= 0.¶ accummulated path length state
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double
previousStepSize
= 0.¶
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double
q
= 0.¶ Save the charge: neutral as default for SL stepper.
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ConstrainedStep
stepSize
= std::numeric_limits<double>::max()¶ adaptive step size of the runge-kutta integration
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double
t
= 0.¶ Propagated time.
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double
tolerance
= s_onSurfaceTolerance¶ The tolerance for the stepping.
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using