1 // Ceres Solver - A fast non-linear least squares minimizer
2 // Copyright 2015 Google Inc. All rights reserved.
3 // http://ceres-solver.org/
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29 // Author: sameeragarwal@google.com (Sameer Agarwal)
31 #ifndef CERES_INTERNAL_LEVENBERG_MARQUARDT_STRATEGY_H_
32 #define CERES_INTERNAL_LEVENBERG_MARQUARDT_STRATEGY_H_
34 #include "ceres/internal/eigen.h"
35 #include "ceres/trust_region_strategy.h"
40 // Levenberg-Marquardt step computation and trust region sizing
41 // strategy based on on "Methods for Nonlinear Least Squares" by
42 // K. Madsen, H.B. Nielsen and O. Tingleff. Available to download from
44 // http://www2.imm.dtu.dk/pubdb/views/edoc_download.php/3215/pdf/imm3215.pdf
45 class LevenbergMarquardtStrategy : public TrustRegionStrategy {
47 explicit LevenbergMarquardtStrategy(
48 const TrustRegionStrategy::Options& options);
49 virtual ~LevenbergMarquardtStrategy();
51 // TrustRegionStrategy interface
52 virtual TrustRegionStrategy::Summary ComputeStep(
53 const TrustRegionStrategy::PerSolveOptions& per_solve_options,
54 SparseMatrix* jacobian,
55 const double* residuals,
57 virtual void StepAccepted(double step_quality);
58 virtual void StepRejected(double step_quality);
59 virtual void StepIsInvalid() {
60 // Treat the current step as a rejected step with no increase in
61 // solution quality. Since rejected steps lead to decrease in the
62 // size of the trust region, the next time ComputeStep is called,
63 // this will lead to a better conditioned system.
67 virtual double Radius() const;
70 LinearSolver* linear_solver_;
73 const double min_diagonal_;
74 const double max_diagonal_;
75 double decrease_factor_;
77 Vector diagonal_; // diagonal_ = diag(J'J)
78 // Scaled copy of diagonal_. Stored here as optimization to prevent
79 // allocations in every iteration and reuse when a step fails and
80 // ComputeStep is called again.
81 Vector lm_diagonal_; // lm_diagonal_ = diagonal_ / radius_;
84 } // namespace internal
87 #endif // CERES_INTERNAL_LEVENBERG_MARQUARDT_STRATEGY_H_