1 // Ceres Solver - A fast non-linear least squares minimizer
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28 //
29 // Author: sameeragarwal@google.com (Sameer Agarwal)
30 //
31 // For generalized bi-partite Jacobian matrices that arise in
32 // Structure from Motion related problems, it is sometimes useful to
33 // have access to the two parts of the matrix as linear operators
34 // themselves. This class provides that functionality.
35 
36 #ifndef CERES_INTERNAL_PARTITIONED_MATRIX_VIEW_H_
37 #define CERES_INTERNAL_PARTITIONED_MATRIX_VIEW_H_
38 
39 #include <algorithm>
40 #include <cstring>
41 #include <vector>
42 
43 #include "ceres/block_structure.h"
44 #include "ceres/internal/eigen.h"
45 #include "ceres/internal/port.h"
46 #include "ceres/linear_solver.h"
47 #include "ceres/small_blas.h"
48 #include "glog/logging.h"
49 
50 namespace ceres {
51 namespace internal {
52 
53 // Given generalized bi-partite matrix A = [E F], with the same block
54 // structure as required by the Schur complement based solver, found
55 // in explicit_schur_complement_solver.h, provide access to the
56 // matrices E and F and their outer products E'E and F'F with
57 // themselves.
58 //
59 // Lack of BlockStructure object will result in a crash and if the
60 // block structure of the matrix does not satisfy the requirements of
61 // the Schur complement solver it will result in unpredictable and
62 // wrong output.
63 class CERES_EXPORT_INTERNAL PartitionedMatrixViewBase {
64  public:
~PartitionedMatrixViewBase()65   virtual ~PartitionedMatrixViewBase() {}
66 
67   // y += E'x
68   virtual void LeftMultiplyE(const double* x, double* y) const = 0;
69 
70   // y += F'x
71   virtual void LeftMultiplyF(const double* x, double* y) const = 0;
72 
73   // y += Ex
74   virtual void RightMultiplyE(const double* x, double* y) const = 0;
75 
76   // y += Fx
77   virtual void RightMultiplyF(const double* x, double* y) const = 0;
78 
79   // Create and return the block diagonal of the matrix E'E.
80   virtual BlockSparseMatrix* CreateBlockDiagonalEtE() const = 0;
81 
82   // Create and return the block diagonal of the matrix F'F. Caller
83   // owns the result.
84   virtual BlockSparseMatrix* CreateBlockDiagonalFtF() const = 0;
85 
86   // Compute the block diagonal of the matrix E'E and store it in
87   // block_diagonal. The matrix block_diagonal is expected to have a
88   // BlockStructure (preferably created using
89   // CreateBlockDiagonalMatrixEtE) which is has the same structure as
90   // the block diagonal of E'E.
91   virtual void UpdateBlockDiagonalEtE(
92       BlockSparseMatrix* block_diagonal) const = 0;
93 
94   // Compute the block diagonal of the matrix F'F and store it in
95   // block_diagonal. The matrix block_diagonal is expected to have a
96   // BlockStructure (preferably created using
97   // CreateBlockDiagonalMatrixFtF) which is has the same structure as
98   // the block diagonal of F'F.
99   virtual void UpdateBlockDiagonalFtF(
100       BlockSparseMatrix* block_diagonal) const = 0;
101 
102   // clang-format off
103   virtual int num_col_blocks_e() const = 0;
104   virtual int num_col_blocks_f() const = 0;
105   virtual int num_cols_e()       const = 0;
106   virtual int num_cols_f()       const = 0;
107   virtual int num_rows()         const = 0;
108   virtual int num_cols()         const = 0;
109   // clang-format on
110 
111   static PartitionedMatrixViewBase* Create(const LinearSolver::Options& options,
112                                            const BlockSparseMatrix& matrix);
113 };
114 
115 template <int kRowBlockSize = Eigen::Dynamic,
116           int kEBlockSize = Eigen::Dynamic,
117           int kFBlockSize = Eigen::Dynamic>
118 class PartitionedMatrixView : public PartitionedMatrixViewBase {
119  public:
120   // matrix = [E F], where the matrix E contains the first
121   // num_col_blocks_a column blocks.
122   PartitionedMatrixView(const BlockSparseMatrix& matrix, int num_col_blocks_e);
123 
124   virtual ~PartitionedMatrixView();
125   void LeftMultiplyE(const double* x, double* y) const final;
126   void LeftMultiplyF(const double* x, double* y) const final;
127   void RightMultiplyE(const double* x, double* y) const final;
128   void RightMultiplyF(const double* x, double* y) const final;
129   BlockSparseMatrix* CreateBlockDiagonalEtE() const final;
130   BlockSparseMatrix* CreateBlockDiagonalFtF() const final;
131   void UpdateBlockDiagonalEtE(BlockSparseMatrix* block_diagonal) const final;
132   void UpdateBlockDiagonalFtF(BlockSparseMatrix* block_diagonal) const final;
133   // clang-format off
num_col_blocks_e()134   int num_col_blocks_e() const final { return num_col_blocks_e_;  }
num_col_blocks_f()135   int num_col_blocks_f() const final { return num_col_blocks_f_;  }
num_cols_e()136   int num_cols_e()       const final { return num_cols_e_;        }
num_cols_f()137   int num_cols_f()       const final { return num_cols_f_;        }
num_rows()138   int num_rows()         const final { return matrix_.num_rows(); }
num_cols()139   int num_cols()         const final { return matrix_.num_cols(); }
140   // clang-format on
141 
142  private:
143   BlockSparseMatrix* CreateBlockDiagonalMatrixLayout(int start_col_block,
144                                                      int end_col_block) const;
145 
146   const BlockSparseMatrix& matrix_;
147   int num_row_blocks_e_;
148   int num_col_blocks_e_;
149   int num_col_blocks_f_;
150   int num_cols_e_;
151   int num_cols_f_;
152 };
153 
154 }  // namespace internal
155 }  // namespace ceres
156 
157 #endif  // CERES_INTERNAL_PARTITIONED_MATRIX_VIEW_H_
158