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Warning, file /include/Acts/Propagator/RiddersPropagator.hpp was not indexed or was modified since last indexation (in which case cross-reference links may be missing, inaccurate or erroneous).
0001 // This file is part of the Acts project. 0002 // 0003 // Copyright (C) 2017-2019 CERN for the benefit of the Acts project 0004 // 0005 // This Source Code Form is subject to the terms of the Mozilla Public 0006 // License, v. 2.0. If a copy of the MPL was not distributed with this 0007 // file, You can obtain one at http://mozilla.org/MPL/2.0/. 0008 0009 #pragma once 0010 0011 #include "Acts/Propagator/Propagator.hpp" 0012 #include "Acts/Surfaces/Surface.hpp" 0013 0014 namespace Acts { 0015 0016 /// @brief This class performs the Ridders algorithm to estimate the propagation 0017 /// of the covariance to a certain point in space. 0018 /// 0019 /// The algorithm is based on the small deviations of the start parameters based 0020 /// on their uncertainty at the beginning of the propgation. This deviation is 0021 /// represented here by a vector of relative deviations of these parameters and 0022 /// fix for all parameters. So, a common choice has to be found that is able to 0023 /// actually fit into the order of magnitude of the uncertainty of each 0024 /// parameter. Using these deviations, the propagation is repeated multiple 0025 /// times and the final covariance matrix at a given target surface is 0026 /// afterwards evaluated by first order derivatives of the final state 0027 /// parameters wrt. the initial parameters. Therefore this evaluation represents 0028 /// a first order approximation of the transport jacobian. Since performing 0029 /// multiple propagations and a numerical evaluation of the covariance requires 0030 /// more time than a single propagation towards a target + a common propagation 0031 /// of the covariance, this class just serves to verify the results of the 0032 /// latter classes. 0033 template <typename propagator_t> 0034 class RiddersPropagator { 0035 using Jacobian = BoundMatrix; 0036 using Covariance = BoundSquareMatrix; 0037 0038 /// 0039 /// @note The result_type_helper struct and the action_list_t_result_t are 0040 /// here to allow a look'n'feel of this class like the Propagator itself 0041 /// 0042 0043 /// @brief Helper struct determining the result's type 0044 /// 0045 /// @tparam parameters_t Type of final track parameters 0046 /// @tparam action_list_t List of propagation action types 0047 /// 0048 /// This helper struct provides type definitions to extract the correct 0049 /// propagation result type from a given TrackParameter type and an 0050 /// ActionList. 0051 /// 0052 template <typename parameters_t, typename action_list_t> 0053 struct result_type_helper { 0054 /// @brief Propagation result type for an arbitrary list of additional 0055 /// propagation results 0056 /// 0057 /// @tparam args Parameter pack specifying additional propagation results 0058 /// 0059 template <typename... args> 0060 using this_result_type = PropagatorResult<parameters_t, args...>; 0061 0062 /// @brief Propagation result type derived from a given action list 0063 using type = typename action_list_t::template result_type<this_result_type>; 0064 }; 0065 0066 /// @brief Short-hand type definition for propagation result derived from 0067 /// an action list 0068 /// 0069 /// @tparam parameters_t Type of the final track parameters 0070 /// @tparam action_list_t List of propagation action types 0071 /// 0072 template <typename parameters_t, typename action_list_t> 0073 using action_list_t_result_t = 0074 typename result_type_helper<parameters_t, action_list_t>::type; 0075 0076 public: 0077 struct Config { 0078 /// Set of deltas which will be added to the nominal track parameters 0079 std::vector<double> deviations = {-4e-4, -2e-4, 2e-4, 4e-4}; 0080 /// See `deviations` - these are applied for disc surfaces 0081 std::vector<double> deviationsDisc = {-3e-5, -1e-5, 1e-5, 3e-5}; 0082 }; 0083 0084 /// @brief Constructor using a propagator 0085 /// 0086 /// @param [in] propagator Underlying propagator that will be used 0087 /// @param [in] config Config for the Ridders propagation 0088 RiddersPropagator(propagator_t propagator, Config config = {}) 0089 : m_propagator(std::move(propagator)), m_config(std::move(config)) {} 0090 0091 /// @brief Constructor building a propagator 0092 /// 0093 /// @tparam stepper_t Type of the stepper 0094 /// @tparam navigator_t Type of the navigator 0095 /// 0096 /// @param [in] stepper Stepper that will be used 0097 /// @param [in] navigator Navigator that will be used 0098 /// @param [in] config Config for the Ridders propagation 0099 template <typename stepper_t, typename navigator_t = VoidNavigator> 0100 RiddersPropagator(stepper_t stepper, navigator_t navigator = navigator_t(), 0101 Config config = {}) 0102 : m_propagator(std::move(stepper), std::move(navigator)), 0103 m_config(std::move(config)) {} 0104 0105 /// @brief Propagation method targeting curvilinear parameters 0106 /// 0107 /// @tparam parameters_t Type of the start parameters 0108 /// @tparam propagator_options_t Type of the propagator options 0109 /// 0110 /// @param [in] start Start parameters 0111 /// @param [in] options Options of the propagations 0112 /// 0113 /// @return Result of the propagation 0114 template <typename parameters_t, typename propagator_options_t> 0115 Result< 0116 action_list_t_result_t<CurvilinearTrackParameters, 0117 typename propagator_options_t::action_list_type>> 0118 propagate(const parameters_t& start, 0119 const propagator_options_t& options) const; 0120 0121 /// @brief Propagation method targeting bound parameters 0122 /// 0123 /// @tparam parameters_t Type of the start parameters 0124 /// @tparam propagator_options_t Type of the propagator options 0125 /// 0126 /// @param [in] start Start parameters 0127 /// @param [in] target The target surface 0128 /// @param [in] options Options of the propagations 0129 /// 0130 /// @return Result of the propagation 0131 /// @note If the target surface is a disc, the resulting covariance may be 0132 /// inconsistent. In this case a zero matrix is returned. 0133 template <typename parameters_t, typename propagator_options_t> 0134 Result<action_list_t_result_t< 0135 BoundTrackParameters, typename propagator_options_t::action_list_type>> 0136 propagate(const parameters_t& start, const Surface& target, 0137 const propagator_options_t& options) const; 0138 0139 private: 0140 /// Does the actual ridders propagation by wiggling the parameters and 0141 /// propagating again. This function is called from the different propagation 0142 /// overloads in order to deduplicate code. 0143 /// 0144 /// @param [in] options Options of the propagations 0145 /// @param [in] start Start parameters 0146 /// @param [in] nominalResult The result of the nominal propagation 0147 template <typename propagator_options_t, typename parameters_t, 0148 typename result_t> 0149 Jacobian wiggleAndCalculateJacobian(const propagator_options_t& options, 0150 const parameters_t& start, 0151 result_t& nominalResult) const; 0152 0153 /// @brief This function tests whether the variations on a disc as target 0154 /// surface lead to results on different sides wrt the center of the disc. 0155 /// This would lead to a flip of the phi value on the surface and therewith to 0156 /// a huge variance in that parameter. It can only occur in this algorithm 0157 /// since the ridders algorithm is unaware of the target surface. 0158 /// 0159 /// @param [in] derivatives Derivatives of a single parameter 0160 /// 0161 /// @return Boolean result whether a phi jump occurred 0162 static bool inconsistentDerivativesOnDisc( 0163 const std::vector<BoundVector>& derivatives); 0164 0165 /// @brief This function wiggles one dimension of the starting parameters, 0166 /// performs the propagation to a surface and collects for each change of the 0167 /// start parameters the slope 0168 /// 0169 /// @tparam options_t PropagatorOptions object 0170 /// @tparam parameters_t Type of the parameters to start the propagation with 0171 /// 0172 /// @param [in] options Options do define how to wiggle 0173 /// @param [in] start Start parameters which will be modified 0174 /// @param [in] param Index to get the parameter that will be modified 0175 /// @param [in] target Target surface 0176 /// @param [in] nominal Nominal end parameters 0177 /// @param [in] deviations Vector of deviations 0178 /// 0179 /// @return Vector containing each slope 0180 template <typename propagator_options_t, typename parameters_t> 0181 std::vector<BoundVector> wiggleParameter( 0182 const propagator_options_t& options, const parameters_t& start, 0183 unsigned int param, const Surface& target, const BoundVector& nominal, 0184 const std::vector<double>& deviations) const; 0185 0186 /// @brief This function fits the jacobian with the deviations and derivatives as input. 0187 /// 0188 /// @param [in] deviations Vector of deviations 0189 /// @param [in] derivatives Slopes of each modification of the parameters 0190 /// 0191 /// @return Propagated jacobian matrix 0192 static Jacobian calculateJacobian( 0193 const std::vector<double>& deviations, 0194 const std::array<std::vector<BoundVector>, eBoundSize>& derivatives); 0195 0196 /// @brief This function fits a linear function through the final state 0197 /// parametrisations 0198 /// 0199 /// @param [in] deviations Vector of deviations 0200 /// @param [in] derivatives Vector of resulting derivatives 0201 /// 0202 /// @return Vector containing the linear fit 0203 static BoundVector fitLinear(const std::vector<double>& deviations, 0204 const std::vector<BoundVector>& derivatives); 0205 0206 propagator_t m_propagator; 0207 Config m_config; 0208 }; 0209 } // namespace Acts 0210 0211 #include "Acts/Propagator/RiddersPropagator.ipp"
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