| // Ceres Solver - A fast non-linear least squares minimizer |
| // Copyright 2022 Google Inc. All rights reserved. |
| // http://ceres-solver.org/ |
| // |
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| // |
| // Author: markshachkov@gmail.com (Mark Shachkov) |
| |
| #include "ceres/power_series_expansion_preconditioner.h" |
| |
| namespace ceres::internal { |
| |
| PowerSeriesExpansionPreconditioner::PowerSeriesExpansionPreconditioner( |
| const ImplicitSchurComplement* isc, |
| const int max_num_spse_iterations, |
| const double spse_tolerance) |
| : isc_(isc), |
| max_num_spse_iterations_(max_num_spse_iterations), |
| spse_tolerance_(spse_tolerance) {} |
| |
| PowerSeriesExpansionPreconditioner::~PowerSeriesExpansionPreconditioner() = |
| default; |
| |
| bool PowerSeriesExpansionPreconditioner::Update(const LinearOperator& A, |
| const double* D) { |
| return true; |
| } |
| |
| void PowerSeriesExpansionPreconditioner::RightMultiplyAndAccumulate( |
| const double* x, double* y) const { |
| VectorRef yref(y, num_rows()); |
| Vector series_term(num_rows()); |
| Vector previous_series_term(num_rows()); |
| yref.setZero(); |
| isc_->block_diagonal_FtF_inverse()->RightMultiplyAndAccumulate(x, y); |
| previous_series_term = yref; |
| |
| const double norm_threshold = spse_tolerance_ * yref.norm(); |
| |
| for (int i = 1;; i++) { |
| series_term.setZero(); |
| isc_->InversePowerSeriesOperatorRightMultiplyAccumulate( |
| previous_series_term.data(), series_term.data()); |
| yref += series_term; |
| if (i >= max_num_spse_iterations_ || series_term.norm() < norm_threshold) { |
| break; |
| } |
| std::swap(previous_series_term, series_term); |
| } |
| } |
| |
| int PowerSeriesExpansionPreconditioner::num_rows() const { |
| return isc_->num_rows(); |
| } |
| |
| } // namespace ceres::internal |