// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2023 Google Inc. All rights reserved.
// http://ceres-solver.org/
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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_LINE_SEARCH_MINIMIZER_H_
#define CERES_INTERNAL_LINE_SEARCH_MINIMIZER_H_

#include "ceres/internal/eigen.h"
#include "ceres/internal/export.h"
#include "ceres/minimizer.h"
#include "ceres/solver.h"
#include "ceres/types.h"
#include "glog/logging.h"

namespace ceres::internal {

// Generic line search minimization algorithm.
//
// For example usage, see SolverImpl::Minimize.
class CERES_NO_EXPORT LineSearchMinimizer final : public Minimizer {
 public:
  struct State {
    State(int /*num_parameters*/, int num_effective_parameters)
        : cost(0.0),
          gradient(num_effective_parameters),
          gradient_squared_norm(0.0),
          search_direction(num_effective_parameters),
          directional_derivative(0.0),
          step_size(0.0) {}

    double cost;
    Vector gradient;
    double gradient_squared_norm;
    double gradient_max_norm;
    Vector search_direction;
    double directional_derivative;
    double step_size;
  };

  void Minimize(const Minimizer::Options& options,
                double* parameters,
                Solver::Summary* summary) final;
};

}  // namespace ceres::internal

#endif  // CERES_INTERNAL_LINE_SEARCH_MINIMIZER_H_