1 // Ceres Solver - A fast non-linear least squares minimizer
2 // Copyright 2015 Google Inc. All rights reserved.
3 // http://ceres-solver.org/
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29 // Author: sameeragarwal@google.com (Sameer Agarwal)
31 #include "ceres/dense_normal_cholesky_solver.h"
35 #include "Eigen/Dense"
36 #include "ceres/blas.h"
37 #include "ceres/dense_sparse_matrix.h"
38 #include "ceres/internal/eigen.h"
39 #include "ceres/internal/scoped_ptr.h"
40 #include "ceres/lapack.h"
41 #include "ceres/linear_solver.h"
42 #include "ceres/types.h"
43 #include "ceres/wall_time.h"
48 DenseNormalCholeskySolver::DenseNormalCholeskySolver(
49 const LinearSolver::Options& options)
50 : options_(options) {}
52 LinearSolver::Summary DenseNormalCholeskySolver::SolveImpl(
55 const LinearSolver::PerSolveOptions& per_solve_options,
57 if (options_.dense_linear_algebra_library_type == EIGEN) {
58 return SolveUsingEigen(A, b, per_solve_options, x);
60 return SolveUsingLAPACK(A, b, per_solve_options, x);
64 LinearSolver::Summary DenseNormalCholeskySolver::SolveUsingEigen(
67 const LinearSolver::PerSolveOptions& per_solve_options,
69 EventLogger event_logger("DenseNormalCholeskySolver::Solve");
71 const int num_rows = A->num_rows();
72 const int num_cols = A->num_cols();
74 ConstColMajorMatrixRef Aref = A->matrix();
75 Matrix lhs(num_cols, num_cols);
78 event_logger.AddEvent("Setup");
82 // Using rankUpdate instead of GEMM, exposes the fact that its the
83 // same matrix being multiplied with itself and that the product is
85 lhs.selfadjointView<Eigen::Upper>().rankUpdate(Aref.transpose());
88 Vector rhs = Aref.transpose() * ConstVectorRef(b, num_rows);
90 if (per_solve_options.D != NULL) {
91 ConstVectorRef D(per_solve_options.D, num_cols);
92 lhs += D.array().square().matrix().asDiagonal();
94 event_logger.AddEvent("Product");
96 LinearSolver::Summary summary;
97 summary.num_iterations = 1;
98 summary.termination_type = LINEAR_SOLVER_SUCCESS;
99 Eigen::LLT<Matrix, Eigen::Upper> llt =
100 lhs.selfadjointView<Eigen::Upper>().llt();
102 if (llt.info() != Eigen::Success) {
103 summary.termination_type = LINEAR_SOLVER_FAILURE;
104 summary.message = "Eigen LLT decomposition failed.";
106 summary.termination_type = LINEAR_SOLVER_SUCCESS;
107 summary.message = "Success.";
110 VectorRef(x, num_cols) = llt.solve(rhs);
111 event_logger.AddEvent("Solve");
115 LinearSolver::Summary DenseNormalCholeskySolver::SolveUsingLAPACK(
116 DenseSparseMatrix* A,
118 const LinearSolver::PerSolveOptions& per_solve_options,
120 EventLogger event_logger("DenseNormalCholeskySolver::Solve");
122 if (per_solve_options.D != NULL) {
123 // Temporarily append a diagonal block to the A matrix, but undo
124 // it before returning the matrix to the user.
125 A->AppendDiagonal(per_solve_options.D);
128 const int num_cols = A->num_cols();
129 Matrix lhs(num_cols, num_cols);
130 event_logger.AddEvent("Setup");
134 // Note: This is a bit delicate, it assumes that the stride on this
135 // matrix is the same as the number of rows.
136 BLAS::SymmetricRankKUpdate(A->num_rows(),
144 if (per_solve_options.D != NULL) {
145 // Undo the modifications to the matrix A.
149 // TODO(sameeragarwal): Replace this with a gemv call for true blasness.
151 VectorRef(x, num_cols) =
152 A->matrix().transpose() * ConstVectorRef(b, A->num_rows());
153 event_logger.AddEvent("Product");
155 LinearSolver::Summary summary;
156 summary.num_iterations = 1;
157 summary.termination_type =
158 LAPACK::SolveInPlaceUsingCholesky(num_cols,
162 event_logger.AddEvent("Solve");
165 } // namespace internal