diff --git a/internal/ceres/block_random_access_sparse_matrix.cc b/internal/ceres/block_random_access_sparse_matrix.cc
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+++ b/internal/ceres/block_random_access_sparse_matrix.cc
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+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
+// http://code.google.com/p/ceres-solver/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors may be
+//   used to endorse or promote products derived from this software without
+//   specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: sameeragarwal@google.com (Sameer Agarwal)
+
+#include "ceres/block_random_access_sparse_matrix.h"
+
+#include <algorithm>
+#include <set>
+#include <utility>
+#include <vector>
+#include <glog/logging.h>
+#include "ceres/mutex.h"
+#include "ceres/triplet_sparse_matrix.h"
+#include "ceres/internal/port.h"
+#include "ceres/internal/scoped_ptr.h"
+#include "ceres/types.h"
+
+namespace ceres {
+namespace internal {
+
+BlockRandomAccessSparseMatrix::BlockRandomAccessSparseMatrix(
+    const vector<int>& blocks,
+    const set<pair<int, int> >& block_pairs)
+    : kMaxRowBlocks(10 * 1000 * 1000),
+      blocks_(blocks) {
+  CHECK_LT(blocks.size(), kMaxRowBlocks);
+
+  // Build the row/column layout vector and count the number of scalar
+  // rows/columns.
+  int num_cols = 0;
+  vector<int> col_layout;
+  for (int i = 0; i < blocks_.size(); ++i) {
+    col_layout.push_back(num_cols);
+    num_cols += blocks_[i];
+  }
+
+  // Count the number of scalar non-zero entries and build the layout
+  // object for looking into the values array of the
+  // TripletSparseMatrix.
+  int num_nonzeros = 0;
+  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
+       it != block_pairs.end();
+       ++it) {
+    const int row_block_size = blocks_[it->first];
+    const int col_block_size = blocks_[it->second];
+    num_nonzeros += row_block_size * col_block_size;
+  }
+
+  VLOG(1) << "Matrix Size [" << num_cols
+          << "," << num_cols
+          << "] " << num_nonzeros;
+
+  tsm_.reset(new TripletSparseMatrix(num_cols, num_cols, num_nonzeros));
+  tsm_->set_num_nonzeros(num_nonzeros);
+  int* rows = tsm_->mutable_rows();
+  int* cols = tsm_->mutable_cols();
+  double* values = tsm_->mutable_values();
+
+  int pos = 0;
+  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
+       it != block_pairs.end();
+       ++it) {
+    const int row_block_size = blocks_[it->first];
+    const int col_block_size = blocks_[it->second];
+    layout_[IntPairToLong(it->first, it->second)] =
+        new CellInfo(values + pos);
+    pos += row_block_size * col_block_size;
+  }
+
+  // Fill the sparsity pattern of the underlying matrix.
+  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
+       it != block_pairs.end();
+       ++it) {
+    const int row_block_id = it->first;
+    const int col_block_id = it->second;
+    const int row_block_size = blocks_[row_block_id];
+    const int col_block_size = blocks_[col_block_id];
+    int pos =
+        layout_[IntPairToLong(row_block_id, col_block_id)]->values - values;
+    for (int r = 0; r < row_block_size; ++r) {
+      for (int c = 0; c < col_block_size; ++c, ++pos) {
+          rows[pos] = col_layout[row_block_id] + r;
+          cols[pos] = col_layout[col_block_id] + c;
+          values[pos] = 1.0;
+          DCHECK_LT(rows[pos], tsm_->num_rows());
+          DCHECK_LT(cols[pos], tsm_->num_rows());
+      }
+    }
+  }
+}
+
+// Assume that the user does not hold any locks on any cell blocks
+// when they are calling SetZero.
+BlockRandomAccessSparseMatrix::~BlockRandomAccessSparseMatrix() {
+  for (LayoutType::iterator it = layout_.begin();
+       it != layout_.end();
+       ++it) {
+    delete it->second;
+  }
+}
+
+CellInfo* BlockRandomAccessSparseMatrix::GetCell(int row_block_id,
+                                                 int col_block_id,
+                                                 int* row,
+                                                 int* col,
+                                                 int* row_stride,
+                                                 int* col_stride) {
+  const LayoutType::iterator it  =
+      layout_.find(IntPairToLong(row_block_id, col_block_id));
+  if (it == layout_.end()) {
+    return NULL;
+  }
+
+  // Each cell is stored contiguously as its own little dense matrix.
+  *row = 0;
+  *col = 0;
+  *row_stride = blocks_[row_block_id];
+  *col_stride = blocks_[col_block_id];
+  return it->second;
+}
+
+// Assume that the user does not hold any locks on any cell blocks
+// when they are calling SetZero.
+void BlockRandomAccessSparseMatrix::SetZero() {
+  if (tsm_->num_nonzeros()) {
+    VectorRef(tsm_->mutable_values(),
+              tsm_->num_nonzeros()).setZero();
+  }
+}
+
+}  // namespace internal
+}  // namespace ceres