// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2017 Google Inc. All rights reserved.
// http://ceres-solver.org/
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// Author: sameeragarwal@google.com (Sameer Agarwal)
//
// A simple C++ interface to the Eigen's Sparse Cholesky routines.

#ifndef CERES_INTERNAL_EIGENSPARSE_H_
#define CERES_INTERNAL_EIGENSPARSE_H_

// This include must come before any #ifndef check on Ceres compile options.
#include "ceres/internal/port.h"

#ifdef CERES_USE_EIGEN_SPARSE

#include <memory>
#include <string>

#include "Eigen/SparseCore"
#include "ceres/linear_solver.h"
#include "ceres/sparse_cholesky.h"

namespace ceres {
namespace internal {

class EigenSparseCholesky : public SparseCholesky {
 public:
  // Factory
  static std::unique_ptr<SparseCholesky> Create(
      const OrderingType ordering_type);

  // SparseCholesky interface.
  virtual ~EigenSparseCholesky();
  virtual LinearSolverTerminationType Factorize(
      CompressedRowSparseMatrix* lhs, std::string* message) = 0;
  virtual CompressedRowSparseMatrix::StorageType StorageType() const = 0;
  virtual LinearSolverTerminationType Solve(const double* rhs,
                                            double* solution,
                                            std::string* message) = 0;
};

// Even though the input is double precision linear system, this class
// solves it by computing a single precision Cholesky factorization.
class FloatEigenSparseCholesky : public SparseCholesky {
 public:
  // Factory
  static std::unique_ptr<SparseCholesky> Create(
      const OrderingType ordering_type);

  // SparseCholesky interface.
  virtual ~FloatEigenSparseCholesky();
  virtual LinearSolverTerminationType Factorize(
      CompressedRowSparseMatrix* lhs, std::string* message) = 0;
  virtual CompressedRowSparseMatrix::StorageType StorageType() const = 0;
  virtual LinearSolverTerminationType Solve(const double* rhs,
                                            double* solution,
                                            std::string* message) = 0;
};

}  // namespace internal
}  // namespace ceres

#endif  // CERES_USE_EIGEN_SPARSE

#endif  // CERES_INTERNAL_EIGENSPARSE_H_