// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2015 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
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// modification, are permitted provided that the following conditions are met:
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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_LINEAR_LEAST_SQUARES_PROBLEMS_H_
#define CERES_INTERNAL_LINEAR_LEAST_SQUARES_PROBLEMS_H_

#include <memory>
#include <string>
#include <vector>

#include "ceres/internal/port.h"
#include "ceres/sparse_matrix.h"

namespace ceres {
namespace internal {

// Structure defining a linear least squares problem and if possible
// ground truth solutions. To be used by various LinearSolver tests.
struct CERES_EXPORT_INTERNAL LinearLeastSquaresProblem {
  LinearLeastSquaresProblem() : num_eliminate_blocks(0) {}

  std::unique_ptr<SparseMatrix> A;
  std::unique_ptr<double[]> b;
  std::unique_ptr<double[]> D;
  // If using the schur eliminator then how many of the variable
  // blocks are e_type blocks.
  int num_eliminate_blocks;

  // Solution to min_x |Ax - b|^2
  std::unique_ptr<double[]> x;
  // Solution to min_x |Ax - b|^2 + |Dx|^2
  std::unique_ptr<double[]> x_D;
};

// Factories for linear least squares problem.
CERES_EXPORT_INTERNAL LinearLeastSquaresProblem*
CreateLinearLeastSquaresProblemFromId(int id);

LinearLeastSquaresProblem* LinearLeastSquaresProblem0();
LinearLeastSquaresProblem* LinearLeastSquaresProblem1();
LinearLeastSquaresProblem* LinearLeastSquaresProblem2();
LinearLeastSquaresProblem* LinearLeastSquaresProblem3();
LinearLeastSquaresProblem* LinearLeastSquaresProblem4();

// Write the linear least squares problem to disk. The exact format
// depends on dump_format_type.
bool DumpLinearLeastSquaresProblem(const std::string& filename_base,
                                   DumpFormatType dump_format_type,
                                   const SparseMatrix* A,
                                   const double* D,
                                   const double* b,
                                   const double* x,
                                   int num_eliminate_blocks);
}  // namespace internal
}  // namespace ceres

#endif  // CERES_INTERNAL_LINEAR_LEAST_SQUARES_PROBLEMS_H_