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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
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     21 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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     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/compressed_row_sparse_matrix.h"
     32 
     33 #include <numeric>
     34 #include "ceres/casts.h"
     35 #include "ceres/crs_matrix.h"
     36 #include "ceres/cxsparse.h"
     37 #include "ceres/internal/eigen.h"
     38 #include "ceres/internal/scoped_ptr.h"
     39 #include "ceres/linear_least_squares_problems.h"
     40 #include "ceres/random.h"
     41 #include "ceres/triplet_sparse_matrix.h"
     42 #include "glog/logging.h"
     43 #include "gtest/gtest.h"
     44 
     45 namespace ceres {
     46 namespace internal {
     47 
     48 void CompareMatrices(const SparseMatrix* a, const SparseMatrix* b) {
     49   EXPECT_EQ(a->num_rows(), b->num_rows());
     50   EXPECT_EQ(a->num_cols(), b->num_cols());
     51 
     52   int num_rows = a->num_rows();
     53   int num_cols = a->num_cols();
     54 
     55   for (int i = 0; i < num_cols; ++i) {
     56     Vector x = Vector::Zero(num_cols);
     57     x(i) = 1.0;
     58 
     59     Vector y_a = Vector::Zero(num_rows);
     60     Vector y_b = Vector::Zero(num_rows);
     61 
     62     a->RightMultiply(x.data(), y_a.data());
     63     b->RightMultiply(x.data(), y_b.data());
     64 
     65     EXPECT_EQ((y_a - y_b).norm(), 0);
     66   }
     67 }
     68 
     69 class CompressedRowSparseMatrixTest : public ::testing::Test {
     70  protected :
     71   virtual void SetUp() {
     72     scoped_ptr<LinearLeastSquaresProblem> problem(
     73         CreateLinearLeastSquaresProblemFromId(1));
     74 
     75     CHECK_NOTNULL(problem.get());
     76 
     77     tsm.reset(down_cast<TripletSparseMatrix*>(problem->A.release()));
     78     crsm.reset(new CompressedRowSparseMatrix(*tsm));
     79 
     80     num_rows = tsm->num_rows();
     81     num_cols = tsm->num_cols();
     82 
     83     vector<int>* row_blocks = crsm->mutable_row_blocks();
     84     row_blocks->resize(num_rows);
     85     std::fill(row_blocks->begin(), row_blocks->end(), 1);
     86 
     87     vector<int>* col_blocks = crsm->mutable_col_blocks();
     88     col_blocks->resize(num_cols);
     89     std::fill(col_blocks->begin(), col_blocks->end(), 1);
     90   }
     91 
     92   int num_rows;
     93   int num_cols;
     94 
     95   scoped_ptr<TripletSparseMatrix> tsm;
     96   scoped_ptr<CompressedRowSparseMatrix> crsm;
     97 };
     98 
     99 TEST_F(CompressedRowSparseMatrixTest, RightMultiply) {
    100   CompareMatrices(tsm.get(), crsm.get());
    101 }
    102 
    103 TEST_F(CompressedRowSparseMatrixTest, LeftMultiply) {
    104   for (int i = 0; i < num_rows; ++i) {
    105     Vector a = Vector::Zero(num_rows);
    106     a(i) = 1.0;
    107 
    108     Vector b1 = Vector::Zero(num_cols);
    109     Vector b2 = Vector::Zero(num_cols);
    110 
    111     tsm->LeftMultiply(a.data(), b1.data());
    112     crsm->LeftMultiply(a.data(), b2.data());
    113 
    114     EXPECT_EQ((b1 - b2).norm(), 0);
    115   }
    116 }
    117 
    118 TEST_F(CompressedRowSparseMatrixTest, ColumnNorm) {
    119   Vector b1 = Vector::Zero(num_cols);
    120   Vector b2 = Vector::Zero(num_cols);
    121 
    122   tsm->SquaredColumnNorm(b1.data());
    123   crsm->SquaredColumnNorm(b2.data());
    124 
    125   EXPECT_EQ((b1 - b2).norm(), 0);
    126 }
    127 
    128 TEST_F(CompressedRowSparseMatrixTest, Scale) {
    129   Vector scale(num_cols);
    130   for (int i = 0; i < num_cols; ++i) {
    131     scale(i) = i + 1;
    132   }
    133 
    134   tsm->ScaleColumns(scale.data());
    135   crsm->ScaleColumns(scale.data());
    136   CompareMatrices(tsm.get(), crsm.get());
    137 }
    138 
    139 TEST_F(CompressedRowSparseMatrixTest, DeleteRows) {
    140   // Clear the row and column blocks as these are purely scalar tests.
    141   crsm->mutable_row_blocks()->clear();
    142   crsm->mutable_col_blocks()->clear();
    143   for (int i = 0; i < num_rows; ++i) {
    144     tsm->Resize(num_rows - i, num_cols);
    145     crsm->DeleteRows(crsm->num_rows() - tsm->num_rows());
    146     CompareMatrices(tsm.get(), crsm.get());
    147   }
    148 }
    149 
    150 TEST_F(CompressedRowSparseMatrixTest, AppendRows) {
    151   // Clear the row and column blocks as these are purely scalar tests.
    152   crsm->mutable_row_blocks()->clear();
    153   crsm->mutable_col_blocks()->clear();
    154 
    155   for (int i = 0; i < num_rows; ++i) {
    156     TripletSparseMatrix tsm_appendage(*tsm);
    157     tsm_appendage.Resize(i, num_cols);
    158 
    159     tsm->AppendRows(tsm_appendage);
    160     CompressedRowSparseMatrix crsm_appendage(tsm_appendage);
    161     crsm->AppendRows(crsm_appendage);
    162 
    163     CompareMatrices(tsm.get(), crsm.get());
    164   }
    165 }
    166 
    167 TEST_F(CompressedRowSparseMatrixTest, AppendAndDeleteBlockDiagonalMatrix) {
    168   int num_diagonal_rows = crsm->num_cols();
    169 
    170   scoped_array<double> diagonal(new double[num_diagonal_rows]);
    171   for (int i = 0; i < num_diagonal_rows; ++i) {
    172     diagonal[i] =i;
    173   }
    174 
    175   vector<int> row_and_column_blocks;
    176   row_and_column_blocks.push_back(1);
    177   row_and_column_blocks.push_back(2);
    178   row_and_column_blocks.push_back(2);
    179 
    180   const vector<int> pre_row_blocks = crsm->row_blocks();
    181   const vector<int> pre_col_blocks = crsm->col_blocks();
    182 
    183   scoped_ptr<CompressedRowSparseMatrix> appendage(
    184       CompressedRowSparseMatrix::CreateBlockDiagonalMatrix(
    185           diagonal.get(), row_and_column_blocks));
    186   LOG(INFO) << appendage->row_blocks().size();
    187 
    188   crsm->AppendRows(*appendage);
    189 
    190   const vector<int> post_row_blocks = crsm->row_blocks();
    191   const vector<int> post_col_blocks = crsm->col_blocks();
    192 
    193   vector<int> expected_row_blocks = pre_row_blocks;
    194   expected_row_blocks.insert(expected_row_blocks.end(),
    195                              row_and_column_blocks.begin(),
    196                              row_and_column_blocks.end());
    197 
    198   vector<int> expected_col_blocks = pre_col_blocks;
    199 
    200   EXPECT_EQ(expected_row_blocks, crsm->row_blocks());
    201   EXPECT_EQ(expected_col_blocks, crsm->col_blocks());
    202 
    203   crsm->DeleteRows(num_diagonal_rows);
    204   EXPECT_EQ(crsm->row_blocks(), pre_row_blocks);
    205   EXPECT_EQ(crsm->col_blocks(), pre_col_blocks);
    206 }
    207 
    208 TEST_F(CompressedRowSparseMatrixTest, ToDenseMatrix) {
    209   Matrix tsm_dense;
    210   Matrix crsm_dense;
    211 
    212   tsm->ToDenseMatrix(&tsm_dense);
    213   crsm->ToDenseMatrix(&crsm_dense);
    214 
    215   EXPECT_EQ((tsm_dense - crsm_dense).norm(), 0.0);
    216 }
    217 
    218 TEST_F(CompressedRowSparseMatrixTest, ToCRSMatrix) {
    219   CRSMatrix crs_matrix;
    220   crsm->ToCRSMatrix(&crs_matrix);
    221   EXPECT_EQ(crsm->num_rows(), crs_matrix.num_rows);
    222   EXPECT_EQ(crsm->num_cols(), crs_matrix.num_cols);
    223   EXPECT_EQ(crsm->num_rows() + 1, crs_matrix.rows.size());
    224   EXPECT_EQ(crsm->num_nonzeros(), crs_matrix.cols.size());
    225   EXPECT_EQ(crsm->num_nonzeros(), crs_matrix.values.size());
    226 
    227   for (int i = 0; i < crsm->num_rows() + 1; ++i) {
    228     EXPECT_EQ(crsm->rows()[i], crs_matrix.rows[i]);
    229   }
    230 
    231   for (int i = 0; i < crsm->num_nonzeros(); ++i) {
    232     EXPECT_EQ(crsm->cols()[i], crs_matrix.cols[i]);
    233     EXPECT_EQ(crsm->values()[i], crs_matrix.values[i]);
    234   }
    235 }
    236 
    237 TEST(CompressedRowSparseMatrix, CreateBlockDiagonalMatrix) {
    238   vector<int> blocks;
    239   blocks.push_back(1);
    240   blocks.push_back(2);
    241   blocks.push_back(2);
    242 
    243   Vector diagonal(5);
    244   for (int i = 0; i < 5; ++i) {
    245     diagonal(i) = i + 1;
    246   }
    247 
    248   scoped_ptr<CompressedRowSparseMatrix> matrix(
    249       CompressedRowSparseMatrix::CreateBlockDiagonalMatrix(
    250           diagonal.data(), blocks));
    251 
    252   EXPECT_EQ(matrix->num_rows(), 5);
    253   EXPECT_EQ(matrix->num_cols(), 5);
    254   EXPECT_EQ(matrix->num_nonzeros(), 9);
    255   EXPECT_EQ(blocks, matrix->row_blocks());
    256   EXPECT_EQ(blocks, matrix->col_blocks());
    257 
    258   Vector x(5);
    259   Vector y(5);
    260 
    261   x.setOnes();
    262   y.setZero();
    263   matrix->RightMultiply(x.data(), y.data());
    264   for (int i = 0; i < diagonal.size(); ++i) {
    265     EXPECT_EQ(y[i], diagonal[i]);
    266   }
    267 
    268   y.setZero();
    269   matrix->LeftMultiply(x.data(), y.data());
    270   for (int i = 0; i < diagonal.size(); ++i) {
    271     EXPECT_EQ(y[i], diagonal[i]);
    272   }
    273 
    274   Matrix dense;
    275   matrix->ToDenseMatrix(&dense);
    276   EXPECT_EQ((dense.diagonal() - diagonal).norm(), 0.0);
    277 }
    278 
    279 class SolveLowerTriangularTest : public ::testing::Test {
    280  protected:
    281   void SetUp() {
    282     matrix_.reset(new CompressedRowSparseMatrix(4, 4, 7));
    283     int* rows = matrix_->mutable_rows();
    284     int* cols = matrix_->mutable_cols();
    285     double* values = matrix_->mutable_values();
    286 
    287     rows[0] = 0;
    288     cols[0] = 0;
    289     values[0] = 0.50754;
    290 
    291     rows[1] = 1;
    292     cols[1] = 1;
    293     values[1] = 0.80483;
    294 
    295     rows[2] = 2;
    296     cols[2] = 1;
    297     values[2] = 0.14120;
    298     cols[3] = 2;
    299     values[3] = 0.3;
    300 
    301     rows[3] = 4;
    302     cols[4] = 0;
    303     values[4] = 0.77696;
    304     cols[5] = 1;
    305     values[5] = 0.41860;
    306     cols[6] = 3;
    307     values[6] = 0.88979;
    308 
    309     rows[4] = 7;
    310   }
    311 
    312   scoped_ptr<CompressedRowSparseMatrix> matrix_;
    313 };
    314 
    315 TEST_F(SolveLowerTriangularTest, SolveInPlace) {
    316   double rhs_and_solution[] = {1.0, 1.0, 2.0, 2.0};
    317   double expected[] = {1.970288,  1.242498,  6.081864, -0.057255};
    318   matrix_->SolveLowerTriangularInPlace(rhs_and_solution);
    319   for (int i = 0; i < 4; ++i) {
    320     EXPECT_NEAR(rhs_and_solution[i], expected[i], 1e-4) << i;
    321   }
    322 }
    323 
    324 TEST_F(SolveLowerTriangularTest, TransposeSolveInPlace) {
    325   double rhs_and_solution[] = {1.0, 1.0, 2.0, 2.0};
    326   const double expected[] = { -1.4706, -1.0962, 6.6667, 2.2477};
    327 
    328   matrix_->SolveLowerTriangularTransposeInPlace(rhs_and_solution);
    329   for (int i = 0; i < 4; ++i) {
    330     EXPECT_NEAR(rhs_and_solution[i], expected[i], 1e-4) << i;
    331   }
    332 }
    333 
    334 TEST(CompressedRowSparseMatrix, Transpose) {
    335   //  0  1  0  2  3  0
    336   //  4  6  7  0  0  8
    337   //  9 10  0 11 12  0
    338   // 13  0 14 15  9  0
    339   //  0 16 17  0  0  0
    340 
    341   // Block structure:
    342   //  A  A  A  A  B  B
    343   //  A  A  A  A  B  B
    344   //  A  A  A  A  B  B
    345   //  C  C  C  C  D  D
    346   //  C  C  C  C  D  D
    347   //  C  C  C  C  D  D
    348 
    349   CompressedRowSparseMatrix matrix(5, 6, 30);
    350   int* rows = matrix.mutable_rows();
    351   int* cols = matrix.mutable_cols();
    352   double* values = matrix.mutable_values();
    353   matrix.mutable_row_blocks()->push_back(3);
    354   matrix.mutable_row_blocks()->push_back(3);
    355   matrix.mutable_col_blocks()->push_back(4);
    356   matrix.mutable_col_blocks()->push_back(2);
    357 
    358   rows[0] = 0;
    359   cols[0] = 1;
    360   cols[1] = 3;
    361   cols[2] = 4;
    362 
    363   rows[1] = 3;
    364   cols[3] = 0;
    365   cols[4] = 1;
    366   cols[5] = 2;
    367   cols[6] = 5;
    368 
    369 
    370   rows[2] = 7;
    371   cols[7] = 0;
    372   cols[8] = 1;
    373   cols[9] = 3;
    374   cols[10] = 4;
    375 
    376   rows[3] = 11;
    377   cols[11] = 0;
    378   cols[12] = 2;
    379   cols[13] = 3;
    380   cols[14] = 4;
    381 
    382   rows[4] = 15;
    383   cols[15] = 1;
    384   cols[16] = 2;
    385   rows[5] = 17;
    386 
    387   copy(values, values + 17, cols);
    388 
    389   scoped_ptr<CompressedRowSparseMatrix> transpose(matrix.Transpose());
    390 
    391   ASSERT_EQ(transpose->row_blocks().size(), matrix.col_blocks().size());
    392   for (int i = 0; i < transpose->row_blocks().size(); ++i) {
    393     EXPECT_EQ(transpose->row_blocks()[i], matrix.col_blocks()[i]);
    394   }
    395 
    396   ASSERT_EQ(transpose->col_blocks().size(), matrix.row_blocks().size());
    397   for (int i = 0; i < transpose->col_blocks().size(); ++i) {
    398     EXPECT_EQ(transpose->col_blocks()[i], matrix.row_blocks()[i]);
    399   }
    400 
    401   Matrix dense_matrix;
    402   matrix.ToDenseMatrix(&dense_matrix);
    403 
    404   Matrix dense_transpose;
    405   transpose->ToDenseMatrix(&dense_transpose);
    406   EXPECT_NEAR((dense_matrix - dense_transpose.transpose()).norm(), 0.0, 1e-14);
    407 }
    408 
    409 #ifndef CERES_NO_CXSPARSE
    410 
    411 struct RandomMatrixOptions {
    412   int num_row_blocks;
    413   int min_row_block_size;
    414   int max_row_block_size;
    415   int num_col_blocks;
    416   int min_col_block_size;
    417   int max_col_block_size;
    418   double block_density;
    419 };
    420 
    421 CompressedRowSparseMatrix* CreateRandomCompressedRowSparseMatrix(
    422     const RandomMatrixOptions& options) {
    423   vector<int> row_blocks;
    424   for (int i = 0; i < options.num_row_blocks; ++i) {
    425     const int delta_block_size =
    426         Uniform(options.max_row_block_size - options.min_row_block_size);
    427     row_blocks.push_back(options.min_row_block_size + delta_block_size);
    428   }
    429 
    430   vector<int> col_blocks;
    431   for (int i = 0; i < options.num_col_blocks; ++i) {
    432     const int delta_block_size =
    433         Uniform(options.max_col_block_size - options.min_col_block_size);
    434     col_blocks.push_back(options.min_col_block_size + delta_block_size);
    435   }
    436 
    437   vector<int> rows;
    438   vector<int> cols;
    439   vector<double> values;
    440 
    441   while (values.size() == 0) {
    442     int row_block_begin = 0;
    443     for (int r = 0; r < options.num_row_blocks; ++r) {
    444       int col_block_begin = 0;
    445       for (int c = 0; c < options.num_col_blocks; ++c) {
    446         if (RandDouble() <= options.block_density) {
    447           for (int i = 0; i < row_blocks[r]; ++i) {
    448             for (int j = 0; j < col_blocks[c]; ++j) {
    449               rows.push_back(row_block_begin + i);
    450               cols.push_back(col_block_begin + j);
    451               values.push_back(RandNormal());
    452             }
    453           }
    454         }
    455         col_block_begin += col_blocks[c];
    456       }
    457       row_block_begin += row_blocks[r];
    458     }
    459   }
    460 
    461   const int num_rows = std::accumulate(row_blocks.begin(), row_blocks.end(), 0);
    462   const int num_cols = std::accumulate(col_blocks.begin(), col_blocks.end(), 0);
    463   const int num_nonzeros = values.size();
    464 
    465   TripletSparseMatrix tsm(num_rows, num_cols, num_nonzeros);
    466   std::copy(rows.begin(), rows.end(), tsm.mutable_rows());
    467   std::copy(cols.begin(), cols.end(), tsm.mutable_cols());
    468   std::copy(values.begin(), values.end(), tsm.mutable_values());
    469   tsm.set_num_nonzeros(num_nonzeros);
    470   CompressedRowSparseMatrix* matrix = new CompressedRowSparseMatrix(tsm);
    471   (*matrix->mutable_row_blocks())  = row_blocks;
    472   (*matrix->mutable_col_blocks())  = col_blocks;
    473   return matrix;
    474 }
    475 
    476 void ToDenseMatrix(const cs_di* matrix, Matrix* dense_matrix) {
    477   dense_matrix->resize(matrix->m, matrix->n);
    478   dense_matrix->setZero();
    479 
    480   for (int c = 0; c < matrix->n; ++c) {
    481    for (int idx = matrix->p[c]; idx < matrix->p[c + 1]; ++idx) {
    482      const int r = matrix->i[idx];
    483      (*dense_matrix)(r, c) = matrix->x[idx];
    484    }
    485  }
    486 }
    487 
    488 TEST(CompressedRowSparseMatrix, ComputeOuterProduct) {
    489   // "Randomly generated seed."
    490   SetRandomState(29823);
    491   int kMaxNumRowBlocks = 10;
    492   int kMaxNumColBlocks = 10;
    493   int kNumTrials = 10;
    494 
    495   CXSparse cxsparse;
    496   const double kTolerance = 1e-18;
    497 
    498   // Create a random matrix, compute its outer product using CXSParse
    499   // and ComputeOuterProduct. Convert both matrices to dense matrices
    500   // and compare their upper triangular parts. They should be within
    501   // kTolerance of each other.
    502   for (int num_row_blocks = 1;
    503        num_row_blocks < kMaxNumRowBlocks;
    504        ++num_row_blocks) {
    505     for (int num_col_blocks = 1;
    506          num_col_blocks < kMaxNumColBlocks;
    507          ++num_col_blocks) {
    508       for (int trial = 0; trial < kNumTrials; ++trial) {
    509 
    510 
    511         RandomMatrixOptions options;
    512         options.num_row_blocks = num_row_blocks;
    513         options.num_col_blocks = num_col_blocks;
    514         options.min_row_block_size = 1;
    515         options.max_row_block_size = 5;
    516         options.min_col_block_size = 1;
    517         options.max_col_block_size = 10;
    518         options.block_density = std::max(0.1, RandDouble());
    519 
    520         VLOG(2) << "num row blocks: " << options.num_row_blocks;
    521         VLOG(2) << "num col blocks: " << options.num_col_blocks;
    522         VLOG(2) << "min row block size: " << options.min_row_block_size;
    523         VLOG(2) << "max row block size: " << options.max_row_block_size;
    524         VLOG(2) << "min col block size: " << options.min_col_block_size;
    525         VLOG(2) << "max col block size: " << options.max_col_block_size;
    526         VLOG(2) << "block density: " << options.block_density;
    527 
    528         scoped_ptr<CompressedRowSparseMatrix> matrix(
    529             CreateRandomCompressedRowSparseMatrix(options));
    530 
    531         cs_di cs_matrix_transpose = cxsparse.CreateSparseMatrixTransposeView(matrix.get());
    532         cs_di* cs_matrix = cxsparse.TransposeMatrix(&cs_matrix_transpose);
    533         cs_di* expected_outer_product =
    534             cxsparse.MatrixMatrixMultiply(&cs_matrix_transpose, cs_matrix);
    535 
    536         vector<int> program;
    537         scoped_ptr<CompressedRowSparseMatrix> outer_product(
    538             CompressedRowSparseMatrix::CreateOuterProductMatrixAndProgram(
    539                 *matrix, &program));
    540         CompressedRowSparseMatrix::ComputeOuterProduct(*matrix,
    541                                                        program,
    542                                                        outer_product.get());
    543 
    544         cs_di actual_outer_product =
    545             cxsparse.CreateSparseMatrixTransposeView(outer_product.get());
    546 
    547         ASSERT_EQ(actual_outer_product.m, actual_outer_product.n);
    548         ASSERT_EQ(expected_outer_product->m, expected_outer_product->n);
    549         ASSERT_EQ(actual_outer_product.m, expected_outer_product->m);
    550 
    551         Matrix actual_matrix;
    552         Matrix expected_matrix;
    553 
    554         ToDenseMatrix(expected_outer_product, &expected_matrix);
    555         expected_matrix.triangularView<Eigen::StrictlyLower>().setZero();
    556 
    557         ToDenseMatrix(&actual_outer_product, &actual_matrix);
    558         const double diff_norm = (actual_matrix - expected_matrix).norm() / expected_matrix.norm();
    559         ASSERT_NEAR(diff_norm, 0.0, kTolerance)
    560             << "expected: \n"
    561             << expected_matrix
    562             << "\nactual: \n"
    563             << actual_matrix;
    564 
    565         cxsparse.Free(cs_matrix);
    566         cxsparse.Free(expected_outer_product);
    567       }
    568     }
    569   }
    570 }
    571 
    572 #endif  // CERES_NO_CXSPARSE
    573 
    574 }  // namespace internal
    575 }  // namespace ceres
    576