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      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/
      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 //
      8 // * Redistributions of source code must retain the above copyright notice,
      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
     19 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     20 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
     21 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     22 // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     23 // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     24 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     25 // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     26 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     27 // POSSIBILITY OF SUCH DAMAGE.
     28 //
     29 // Author: sameeragarwal (at) 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 
     44 namespace ceres {
     45 namespace internal {
     46 
     47 BlockRandomAccessSparseMatrix::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.
    120 BlockRandomAccessSparseMatrix::~BlockRandomAccessSparseMatrix() {
    121   for (LayoutType::iterator it = layout_.begin();
    122        it != layout_.end();
    123        ++it) {
    124     delete it->second;
    125   }
    126 }
    127 
    128 CellInfo* 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.
    150 void 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