1// Ceres Solver - A fast non-linear least squares minimizer
2// Copyright 2012 Google Inc. All rights reserved.
3// http://code.google.com/p/ceres-solver/
4//
5// Redistribution and use in source and binary forms, with or without
6// modification, are permitted provided that the following conditions are met:
7//
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9//   this list of conditions and the following disclaimer.
10// * Redistributions in binary form must reproduce the above copyright notice,
11//   this list of conditions and the following disclaimer in the documentation
12//   and/or other materials provided with the distribution.
13// * Neither the name of Google Inc. nor the names of its contributors may be
14//   used to endorse or promote products derived from this software without
15//   specific prior written permission.
16//
17// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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28//
29// Author: keir@google.com (Keir Mierle)
30
31#include "ceres/cgnr_solver.h"
32
33#include "ceres/block_jacobi_preconditioner.h"
34#include "ceres/cgnr_linear_operator.h"
35#include "ceres/conjugate_gradients_solver.h"
36#include "ceres/linear_solver.h"
37#include "ceres/wall_time.h"
38#include "glog/logging.h"
39
40namespace ceres {
41namespace internal {
42
43CgnrSolver::CgnrSolver(const LinearSolver::Options& options)
44  : options_(options),
45    preconditioner_(NULL) {
46}
47
48LinearSolver::Summary CgnrSolver::SolveImpl(
49    BlockSparseMatrix* A,
50    const double* b,
51    const LinearSolver::PerSolveOptions& per_solve_options,
52    double* x) {
53  EventLogger event_logger("CgnrSolver::Solve");
54
55  // Form z = Atb.
56  scoped_array<double> z(new double[A->num_cols()]);
57  std::fill(z.get(), z.get() + A->num_cols(), 0.0);
58  A->LeftMultiply(b, z.get());
59
60  // Precondition if necessary.
61  LinearSolver::PerSolveOptions cg_per_solve_options = per_solve_options;
62  if (options_.preconditioner_type == JACOBI) {
63    if (preconditioner_.get() == NULL) {
64      preconditioner_.reset(new BlockJacobiPreconditioner(*A));
65    }
66    preconditioner_->Update(*A, per_solve_options.D);
67    cg_per_solve_options.preconditioner = preconditioner_.get();
68  } else if (options_.preconditioner_type != IDENTITY) {
69    LOG(FATAL) << "CGNR only supports IDENTITY and JACOBI preconditioners.";
70  }
71
72  // Solve (AtA + DtD)x = z (= Atb).
73  std::fill(x, x + A->num_cols(), 0.0);
74  CgnrLinearOperator lhs(*A, per_solve_options.D);
75  event_logger.AddEvent("Setup");
76
77  ConjugateGradientsSolver conjugate_gradient_solver(options_);
78  LinearSolver::Summary summary =
79      conjugate_gradient_solver.Solve(&lhs, z.get(), cg_per_solve_options, x);
80  event_logger.AddEvent("Solve");
81
82  return summary;
83}
84
85}  // namespace internal
86}  // namespace ceres
87