1// Ceres Solver - A fast non-linear least squares minimizer
2// Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
3// http://code.google.com/p/ceres-solver/
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29// Author: sameeragarwal@google.com (Sameer Agarwal)
30
31#include "ceres/block_random_access_sparse_matrix.h"
32
33#include <algorithm>
34#include <set>
35#include <utility>
36#include <vector>
37#include "ceres/internal/port.h"
38#include "ceres/internal/scoped_ptr.h"
39#include "ceres/mutex.h"
40#include "ceres/triplet_sparse_matrix.h"
41#include "ceres/types.h"
42#include "glog/logging.h"
43
44namespace ceres {
45namespace internal {
46
47BlockRandomAccessSparseMatrix::BlockRandomAccessSparseMatrix(
48    const vector<int>& blocks,
49    const set<pair<int, int> >& block_pairs)
50    : kMaxRowBlocks(10 * 1000 * 1000),
51      blocks_(blocks) {
52  CHECK_LT(blocks.size(), kMaxRowBlocks);
53
54  // Build the row/column layout vector and count the number of scalar
55  // rows/columns.
56  int num_cols = 0;
57  vector<int> col_layout;
58  for (int i = 0; i < blocks_.size(); ++i) {
59    col_layout.push_back(num_cols);
60    num_cols += blocks_[i];
61  }
62
63  // Count the number of scalar non-zero entries and build the layout
64  // object for looking into the values array of the
65  // TripletSparseMatrix.
66  int num_nonzeros = 0;
67  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
68       it != block_pairs.end();
69       ++it) {
70    const int row_block_size = blocks_[it->first];
71    const int col_block_size = blocks_[it->second];
72    num_nonzeros += row_block_size * col_block_size;
73  }
74
75  VLOG(1) << "Matrix Size [" << num_cols
76          << "," << num_cols
77          << "] " << num_nonzeros;
78
79  tsm_.reset(new TripletSparseMatrix(num_cols, num_cols, num_nonzeros));
80  tsm_->set_num_nonzeros(num_nonzeros);
81  int* rows = tsm_->mutable_rows();
82  int* cols = tsm_->mutable_cols();
83  double* values = tsm_->mutable_values();
84
85  int pos = 0;
86  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
87       it != block_pairs.end();
88       ++it) {
89    const int row_block_size = blocks_[it->first];
90    const int col_block_size = blocks_[it->second];
91    layout_[IntPairToLong(it->first, it->second)] =
92        new CellInfo(values + pos);
93    pos += row_block_size * col_block_size;
94  }
95
96  // Fill the sparsity pattern of the underlying matrix.
97  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
98       it != block_pairs.end();
99       ++it) {
100    const int row_block_id = it->first;
101    const int col_block_id = it->second;
102    const int row_block_size = blocks_[row_block_id];
103    const int col_block_size = blocks_[col_block_id];
104    int pos =
105        layout_[IntPairToLong(row_block_id, col_block_id)]->values - values;
106    for (int r = 0; r < row_block_size; ++r) {
107      for (int c = 0; c < col_block_size; ++c, ++pos) {
108          rows[pos] = col_layout[row_block_id] + r;
109          cols[pos] = col_layout[col_block_id] + c;
110          values[pos] = 1.0;
111          DCHECK_LT(rows[pos], tsm_->num_rows());
112          DCHECK_LT(cols[pos], tsm_->num_rows());
113      }
114    }
115  }
116}
117
118// Assume that the user does not hold any locks on any cell blocks
119// when they are calling SetZero.
120BlockRandomAccessSparseMatrix::~BlockRandomAccessSparseMatrix() {
121  for (LayoutType::iterator it = layout_.begin();
122       it != layout_.end();
123       ++it) {
124    delete it->second;
125  }
126}
127
128CellInfo* BlockRandomAccessSparseMatrix::GetCell(int row_block_id,
129                                                 int col_block_id,
130                                                 int* row,
131                                                 int* col,
132                                                 int* row_stride,
133                                                 int* col_stride) {
134  const LayoutType::iterator it  =
135      layout_.find(IntPairToLong(row_block_id, col_block_id));
136  if (it == layout_.end()) {
137    return NULL;
138  }
139
140  // Each cell is stored contiguously as its own little dense matrix.
141  *row = 0;
142  *col = 0;
143  *row_stride = blocks_[row_block_id];
144  *col_stride = blocks_[col_block_id];
145  return it->second;
146}
147
148// Assume that the user does not hold any locks on any cell blocks
149// when they are calling SetZero.
150void BlockRandomAccessSparseMatrix::SetZero() {
151  if (tsm_->num_nonzeros()) {
152    VectorRef(tsm_->mutable_values(),
153              tsm_->num_nonzeros()).setZero();
154  }
155}
156
157}  // namespace internal
158}  // namespace ceres
159