// Ceres Solver - A fast non-linear least squares minimizer
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// http://ceres-solver.org/
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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_COVARIANCE_IMPL_H_
#define CERES_INTERNAL_COVARIANCE_IMPL_H_

#include <memory>
#include <utility>
#include <vector>

#include "absl/container/btree_map.h"
#include "absl/container/btree_set.h"
#include "ceres/covariance.h"
#include "ceres/internal/disable_warnings.h"
#include "ceres/internal/export.h"
#include "ceres/problem_impl.h"
#include "ceres/suitesparse.h"

namespace ceres::internal {

class CompressedRowSparseMatrix;

class CERES_NO_EXPORT CovarianceImpl {
 public:
  explicit CovarianceImpl(const Covariance::Options& options);
  ~CovarianceImpl();

  bool Compute(const std::vector<std::pair<const double*, const double*>>&
                   covariance_blocks,
               ProblemImpl* problem);

  bool Compute(const std::vector<const double*>& parameter_blocks,
               ProblemImpl* problem);

  bool GetCovarianceBlockInTangentOrAmbientSpace(
      const double* parameter_block1,
      const double* parameter_block2,
      bool lift_covariance_to_ambient_space,
      double* covariance_block) const;

  bool GetCovarianceMatrixInTangentOrAmbientSpace(
      const std::vector<const double*>& parameters,
      bool lift_covariance_to_ambient_space,
      double* covariance_matrix) const;

  bool ComputeCovarianceSparsity(
      const std::vector<std::pair<const double*, const double*>>&
          covariance_blocks,
      ProblemImpl* problem);

  bool ComputeCovarianceValues();
  bool ComputeCovarianceValuesUsingDenseSVD();
  bool ComputeCovarianceValuesUsingSuiteSparseQR();
  bool ComputeCovarianceValuesUsingEigenSparseQR();

  const CompressedRowSparseMatrix* covariance_matrix() const {
    return covariance_matrix_.get();
  }

 private:
  ProblemImpl* problem_;
  Covariance::Options options_;
  Problem::EvaluateOptions evaluate_options_;
  bool is_computed_;
  bool is_valid_;
  absl::btree_map<const double*, int> parameter_block_to_row_index_;
  absl::btree_set<const double*> constant_parameter_blocks_;
  std::unique_ptr<CompressedRowSparseMatrix> covariance_matrix_;
};

}  // namespace ceres::internal

#include "ceres/internal/reenable_warnings.h"

#endif  // CERES_INTERNAL_COVARIANCE_IMPL_H_