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diff --git a/extern/libmv/third_party/ceres/include/ceres/gradient_problem_solver.h b/extern/libmv/third_party/ceres/include/ceres/gradient_problem_solver.h new file mode 100644 index 00000000000..484d88ece82 --- /dev/null +++ b/extern/libmv/third_party/ceres/include/ceres/gradient_problem_solver.h @@ -0,0 +1,365 @@ +// Ceres Solver - A fast non-linear least squares minimizer +// Copyright 2014 Google Inc. All rights reserved. +// http://code.google.com/p/ceres-solver/ +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are met: +// +// * Redistributions of source code must retain the above copyright notice, +// this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above copyright notice, +// this list of conditions and the following disclaimer in the documentation +// and/or other materials provided with the distribution. +// * Neither the name of Google Inc. nor the names of its contributors may be +// used to endorse or promote products derived from this software without +// specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" +// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE +// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN +// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +// POSSIBILITY OF SUCH DAMAGE. +// +// Author: sameeragarwal@google.com (Sameer Agarwal) + +#ifndef CERES_PUBLIC_GRADIENT_PROBLEM_SOLVER_H_ +#define CERES_PUBLIC_GRADIENT_PROBLEM_SOLVER_H_ + +#include <cmath> +#include <string> +#include <vector> +#include "ceres/internal/macros.h" +#include "ceres/internal/port.h" +#include "ceres/iteration_callback.h" +#include "ceres/types.h" +#include "ceres/internal/disable_warnings.h" + +namespace ceres { + +class GradientProblem; + +class CERES_EXPORT GradientProblemSolver { + public: + virtual ~GradientProblemSolver(); + + // The options structure contains, not surprisingly, options that control how + // the solver operates. The defaults should be suitable for a wide range of + // problems; however, better performance is often obtainable with tweaking. + // + // The constants are defined inside types.h + struct CERES_EXPORT Options { + // Default constructor that sets up a generic sparse problem. + Options() { + line_search_direction_type = LBFGS; + line_search_type = WOLFE; + nonlinear_conjugate_gradient_type = FLETCHER_REEVES; + max_lbfgs_rank = 20; + use_approximate_eigenvalue_bfgs_scaling = false; + line_search_interpolation_type = CUBIC; + min_line_search_step_size = 1e-9; + line_search_sufficient_function_decrease = 1e-4; + max_line_search_step_contraction = 1e-3; + min_line_search_step_contraction = 0.6; + max_num_line_search_step_size_iterations = 20; + max_num_line_search_direction_restarts = 5; + line_search_sufficient_curvature_decrease = 0.9; + max_line_search_step_expansion = 10.0; + max_num_iterations = 50; + max_solver_time_in_seconds = 1e9; + num_threads = 1; + function_tolerance = 1e-6; + gradient_tolerance = 1e-10; + logging_type = PER_MINIMIZER_ITERATION; + minimizer_progress_to_stdout = false; + } + + // Returns true if the options struct has a valid + // configuration. Returns false otherwise, and fills in *error + // with a message describing the problem. + bool IsValid(string* error) const; + + // Minimizer options ---------------------------------------- + LineSearchDirectionType line_search_direction_type; + LineSearchType line_search_type; + NonlinearConjugateGradientType nonlinear_conjugate_gradient_type; + + // The LBFGS hessian approximation is a low rank approximation to + // the inverse of the Hessian matrix. The rank of the + // approximation determines (linearly) the space and time + // complexity of using the approximation. Higher the rank, the + // better is the quality of the approximation. The increase in + // quality is however is bounded for a number of reasons. + // + // 1. The method only uses secant information and not actual + // derivatives. + // + // 2. The Hessian approximation is constrained to be positive + // definite. + // + // So increasing this rank to a large number will cost time and + // space complexity without the corresponding increase in solution + // quality. There are no hard and fast rules for choosing the + // maximum rank. The best choice usually requires some problem + // specific experimentation. + // + // For more theoretical and implementation details of the LBFGS + // method, please see: + // + // Nocedal, J. (1980). "Updating Quasi-Newton Matrices with + // Limited Storage". Mathematics of Computation 35 (151): 773–782. + int max_lbfgs_rank; + + // As part of the (L)BFGS update step (BFGS) / right-multiply step (L-BFGS), + // the initial inverse Hessian approximation is taken to be the Identity. + // However, Oren showed that using instead I * \gamma, where \gamma is + // chosen to approximate an eigenvalue of the true inverse Hessian can + // result in improved convergence in a wide variety of cases. Setting + // use_approximate_eigenvalue_bfgs_scaling to true enables this scaling. + // + // It is important to note that approximate eigenvalue scaling does not + // always improve convergence, and that it can in fact significantly degrade + // performance for certain classes of problem, which is why it is disabled + // by default. In particular it can degrade performance when the + // sensitivity of the problem to different parameters varies significantly, + // as in this case a single scalar factor fails to capture this variation + // and detrimentally downscales parts of the jacobian approximation which + // correspond to low-sensitivity parameters. It can also reduce the + // robustness of the solution to errors in the jacobians. + // + // Oren S.S., Self-scaling variable metric (SSVM) algorithms + // Part II: Implementation and experiments, Management Science, + // 20(5), 863-874, 1974. + bool use_approximate_eigenvalue_bfgs_scaling; + + // Degree of the polynomial used to approximate the objective + // function. Valid values are BISECTION, QUADRATIC and CUBIC. + // + // BISECTION corresponds to pure backtracking search with no + // interpolation. + LineSearchInterpolationType line_search_interpolation_type; + + // If during the line search, the step_size falls below this + // value, it is truncated to zero. + double min_line_search_step_size; + + // Line search parameters. + + // Solving the line search problem exactly is computationally + // prohibitive. Fortunately, line search based optimization + // algorithms can still guarantee convergence if instead of an + // exact solution, the line search algorithm returns a solution + // which decreases the value of the objective function + // sufficiently. More precisely, we are looking for a step_size + // s.t. + // + // f(step_size) <= f(0) + sufficient_decrease * f'(0) * step_size + // + double line_search_sufficient_function_decrease; + + // In each iteration of the line search, + // + // new_step_size >= max_line_search_step_contraction * step_size + // + // Note that by definition, for contraction: + // + // 0 < max_step_contraction < min_step_contraction < 1 + // + double max_line_search_step_contraction; + + // In each iteration of the line search, + // + // new_step_size <= min_line_search_step_contraction * step_size + // + // Note that by definition, for contraction: + // + // 0 < max_step_contraction < min_step_contraction < 1 + // + double min_line_search_step_contraction; + + // Maximum number of trial step size iterations during each line search, + // if a step size satisfying the search conditions cannot be found within + // this number of trials, the line search will terminate. + int max_num_line_search_step_size_iterations; + + // Maximum number of restarts of the line search direction algorithm before + // terminating the optimization. Restarts of the line search direction + // algorithm occur when the current algorithm fails to produce a new descent + // direction. This typically indicates a numerical failure, or a breakdown + // in the validity of the approximations used. + int max_num_line_search_direction_restarts; + + // The strong Wolfe conditions consist of the Armijo sufficient + // decrease condition, and an additional requirement that the + // step-size be chosen s.t. the _magnitude_ ('strong' Wolfe + // conditions) of the gradient along the search direction + // decreases sufficiently. Precisely, this second condition + // is that we seek a step_size s.t. + // + // |f'(step_size)| <= sufficient_curvature_decrease * |f'(0)| + // + // Where f() is the line search objective and f'() is the derivative + // of f w.r.t step_size (d f / d step_size). + double line_search_sufficient_curvature_decrease; + + // During the bracketing phase of the Wolfe search, the step size is + // increased until either a point satisfying the Wolfe conditions is + // found, or an upper bound for a bracket containing a point satisfying + // the conditions is found. Precisely, at each iteration of the + // expansion: + // + // new_step_size <= max_step_expansion * step_size. + // + // By definition for expansion, max_step_expansion > 1.0. + double max_line_search_step_expansion; + + // Maximum number of iterations for the minimizer to run for. + int max_num_iterations; + + // Maximum time for which the minimizer should run for. + double max_solver_time_in_seconds; + + // Number of threads used by Ceres for evaluating the cost and + // jacobians. + int num_threads; + + // Minimizer terminates when + // + // (new_cost - old_cost) < function_tolerance * old_cost; + // + double function_tolerance; + + // Minimizer terminates when + // + // max_i |x - Project(Plus(x, -g(x))| < gradient_tolerance + // + // This value should typically be 1e-4 * function_tolerance. + double gradient_tolerance; + + // Logging options --------------------------------------------------------- + + LoggingType logging_type; + + // By default the Minimizer progress is logged to VLOG(1), which + // is sent to STDERR depending on the vlog level. If this flag is + // set to true, and logging_type is not SILENT, the logging output + // is sent to STDOUT. + bool minimizer_progress_to_stdout; + + // If true, the user's parameter blocks are updated at the end of + // every Minimizer iteration, otherwise they are updated when the + // Minimizer terminates. This is useful if, for example, the user + // wishes to visualize the state of the optimization every + // iteration. + bool update_state_every_iteration; + + // Callbacks that are executed at the end of each iteration of the + // Minimizer. An iteration may terminate midway, either due to + // numerical failures or because one of the convergence tests has + // been satisfied. In this case none of the callbacks are + // executed. + + // Callbacks are executed in the order that they are specified in + // this vector. By default, parameter blocks are updated only at + // the end of the optimization, i.e when the Minimizer + // terminates. This behaviour is controlled by + // update_state_every_variable. If the user wishes to have access + // to the update parameter blocks when his/her callbacks are + // executed, then set update_state_every_iteration to true. + // + // The solver does NOT take ownership of these pointers. + vector<IterationCallback*> callbacks; + }; + + struct CERES_EXPORT Summary { + Summary(); + + // A brief one line description of the state of the solver after + // termination. + string BriefReport() const; + + // A full multiline description of the state of the solver after + // termination. + string FullReport() const; + + bool IsSolutionUsable() const; + + // Minimizer summary ------------------------------------------------- + TerminationType termination_type; + + // Reason why the solver terminated. + string message; + + // Cost of the problem (value of the objective function) before + // the optimization. + double initial_cost; + + // Cost of the problem (value of the objective function) after the + // optimization. + double final_cost; + + // IterationSummary for each minimizer iteration in order. + vector<IterationSummary> iterations; + + // Sum total of all time spent inside Ceres when Solve is called. + double total_time_in_seconds; + + // Time (in seconds) spent evaluating the residual vector. + double cost_evaluation_time_in_seconds; + + // Time (in seconds) spent evaluating the jacobian matrix. + double gradient_evaluation_time_in_seconds; + + // Number of parameters in the probem. + int num_parameters; + + // Dimension of the tangent space of the problem. + int num_local_parameters; + + // Type of line search direction used. + LineSearchDirectionType line_search_direction_type; + + // Type of the line search algorithm used. + LineSearchType line_search_type; + + // When performing line search, the degree of the polynomial used + // to approximate the objective function. + LineSearchInterpolationType line_search_interpolation_type; + + // If the line search direction is NONLINEAR_CONJUGATE_GRADIENT, + // then this indicates the particular variant of non-linear + // conjugate gradient used. + NonlinearConjugateGradientType nonlinear_conjugate_gradient_type; + + // If the type of the line search direction is LBFGS, then this + // indicates the rank of the Hessian approximation. + int max_lbfgs_rank; + }; + + // Once a least squares problem has been built, this function takes + // the problem and optimizes it based on the values of the options + // parameters. Upon return, a detailed summary of the work performed + // by the preprocessor, the non-linear minmizer and the linear + // solver are reported in the summary object. + virtual void Solve(const GradientProblemSolver::Options& options, + const GradientProblem& problem, + double* parameters, + GradientProblemSolver::Summary* summary); +}; + +// Helper function which avoids going through the interface. +CERES_EXPORT void Solve(const GradientProblemSolver::Options& options, + const GradientProblem& problem, + double* parameters, + GradientProblemSolver::Summary* summary); + +} // namespace ceres + +#include "ceres/internal/reenable_warnings.h" + +#endif // CERES_PUBLIC_GRADIENT_PROBLEM_SOLVER_H_ |