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      1 // Ceres Solver - A fast non-linear least squares minimizer
      2 // Copyright 2013 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_crs_matrix.h"
     32 
     33 #include <algorithm>
     34 #include <set>
     35 #include <utility>
     36 #include <vector>
     37 #include "ceres/compressed_row_sparse_matrix.h"
     38 #include "ceres/internal/port.h"
     39 #include "ceres/internal/scoped_ptr.h"
     40 #include "ceres/mutex.h"
     41 #include "ceres/triplet_sparse_matrix.h"
     42 #include "ceres/types.h"
     43 #include "glog/logging.h"
     44 
     45 namespace ceres {
     46 namespace internal {
     47 
     48 BlockRandomAccessCRSMatrix::BlockRandomAccessCRSMatrix(
     49     const vector<int>& blocks,
     50     const set<pair<int, int> >& block_pairs)
     51     : kMaxRowBlocks(10 * 1000 * 1000),
     52       blocks_(blocks) {
     53   CHECK_LT(blocks.size(), kMaxRowBlocks);
     54 
     55   col_layout_.resize(blocks_.size(), 0);
     56   row_strides_.resize(blocks_.size(), 0);
     57 
     58   // Build the row/column layout vector and count the number of scalar
     59   // rows/columns.
     60   int num_cols = 0;
     61   for (int i = 0; i < blocks_.size(); ++i) {
     62     col_layout_[i] = num_cols;
     63     num_cols += blocks_[i];
     64   }
     65 
     66   // Walk the sparsity pattern and count the number of non-zeros.
     67   int num_nonzeros = 0;
     68   for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
     69        it != block_pairs.end();
     70        ++it) {
     71     const int row_block_size = blocks_[it->first];
     72     const int col_block_size = blocks_[it->second];
     73     num_nonzeros += row_block_size * col_block_size;
     74   }
     75 
     76   VLOG(2) << "Matrix Size [" << num_cols
     77           << "," << num_cols
     78           << "] " << num_nonzeros;
     79 
     80   crsm_.reset(new CompressedRowSparseMatrix(num_cols, num_cols, num_nonzeros));
     81   int* rows = crsm_->mutable_rows();
     82   int* cols = crsm_->mutable_cols();
     83   double* values = crsm_->mutable_values();
     84 
     85   // Iterate over the sparsity pattern and fill the scalar sparsity
     86   // pattern of the underlying compressed sparse row matrix. Along the
     87   // way also fill out the Layout object which will allow random
     88   // access into the CRS Matrix.
     89   set<pair<int, int> >::const_iterator it = block_pairs.begin();
     90   vector<int> col_blocks;
     91   int row_pos = 0;
     92   rows[0] = 0;
     93   while (it != block_pairs.end()) {
     94     // Add entries to layout_ for all the blocks for this row.
     95     col_blocks.clear();
     96     const int row_block_id = it->first;
     97     const int row_block_size = blocks_[row_block_id];
     98     int num_cols = 0;
     99     while ((it != block_pairs.end()) && (it->first == row_block_id)) {
    100       layout_[IntPairToLong(it->first, it->second)] =
    101           new CellInfo(values + num_cols);
    102       col_blocks.push_back(it->second);
    103       num_cols += blocks_[it->second];
    104       ++it;
    105     };
    106 
    107     // Count the number of non-zeros in the row block.
    108     for (int j = 0; j < row_block_size; ++j) {
    109       rows[row_pos + j + 1] = rows[row_pos + j] + num_cols;
    110     }
    111 
    112     // Fill out the sparsity pattern for each row.
    113     int col_pos = 0;
    114     for (int j = 0; j < col_blocks.size(); ++j) {
    115       const int col_block_id = col_blocks[j];
    116       const int col_block_size = blocks_[col_block_id];
    117       for (int r = 0; r < row_block_size; ++r) {
    118         const int column_block_begin = rows[row_pos + r] + col_pos;
    119         for (int c = 0; c < col_block_size; ++c) {
    120           cols[column_block_begin + c] = col_layout_[col_block_id] + c;
    121         }
    122       }
    123       col_pos += col_block_size;
    124     }
    125 
    126     row_pos += row_block_size;
    127     values += row_block_size * num_cols;
    128     row_strides_[row_block_id] = num_cols;
    129   }
    130 }
    131 
    132 // Assume that the user does not hold any locks on any cell blocks
    133 // when they are calling SetZero.
    134 BlockRandomAccessCRSMatrix::~BlockRandomAccessCRSMatrix() {
    135   // TODO(sameeragarwal) this should be rationalized going forward and
    136   // perhaps moved into BlockRandomAccessMatrix.
    137   for (LayoutType::iterator it = layout_.begin();
    138        it != layout_.end();
    139        ++it) {
    140     delete it->second;
    141   }
    142 }
    143 
    144 CellInfo* BlockRandomAccessCRSMatrix::GetCell(int row_block_id,
    145                                               int col_block_id,
    146                                               int* row,
    147                                               int* col,
    148                                               int* row_stride,
    149                                               int* col_stride) {
    150   const LayoutType::iterator it  =
    151       layout_.find(IntPairToLong(row_block_id, col_block_id));
    152   if (it == layout_.end()) {
    153     return NULL;
    154   }
    155 
    156   *row = 0;
    157   *col = 0;
    158   *row_stride = blocks_[row_block_id];
    159   *col_stride = row_strides_[row_block_id];
    160   return it->second;
    161 }
    162 
    163 // Assume that the user does not hold any locks on any cell blocks
    164 // when they are calling SetZero.
    165 void BlockRandomAccessCRSMatrix::SetZero() {
    166   crsm_->SetZero();
    167 }
    168 
    169 }  // namespace internal
    170 }  // namespace ceres
    171