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      1 // Ceres Solver - A fast non-linear least squares minimizer
      2 // Copyright 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: strandmark (at) google.com (Petter Strandmark)
     30 
     31 // This include must come before any #ifndef check on Ceres compile options.
     32 #include "ceres/internal/port.h"
     33 
     34 #ifndef CERES_NO_CXSPARSE
     35 
     36 #include "ceres/cxsparse.h"
     37 
     38 #include <vector>
     39 #include "ceres/compressed_col_sparse_matrix_utils.h"
     40 #include "ceres/compressed_row_sparse_matrix.h"
     41 #include "ceres/internal/port.h"
     42 #include "ceres/triplet_sparse_matrix.h"
     43 #include "glog/logging.h"
     44 
     45 namespace ceres {
     46 namespace internal {
     47 
     48 CXSparse::CXSparse() : scratch_(NULL), scratch_size_(0) {
     49 }
     50 
     51 CXSparse::~CXSparse() {
     52   if (scratch_size_ > 0) {
     53     cs_di_free(scratch_);
     54   }
     55 }
     56 
     57 
     58 bool CXSparse::SolveCholesky(cs_di* A,
     59                              cs_dis* symbolic_factorization,
     60                              double* b) {
     61   // Make sure we have enough scratch space available.
     62   if (scratch_size_ < A->n) {
     63     if (scratch_size_ > 0) {
     64       cs_di_free(scratch_);
     65     }
     66     scratch_ =
     67         reinterpret_cast<CS_ENTRY*>(cs_di_malloc(A->n, sizeof(CS_ENTRY)));
     68     scratch_size_ = A->n;
     69   }
     70 
     71   // Solve using Cholesky factorization
     72   csn* numeric_factorization = cs_di_chol(A, symbolic_factorization);
     73   if (numeric_factorization == NULL) {
     74     LOG(WARNING) << "Cholesky factorization failed.";
     75     return false;
     76   }
     77 
     78   // When the Cholesky factorization succeeded, these methods are
     79   // guaranteed to succeeded as well. In the comments below, "x"
     80   // refers to the scratch space.
     81   //
     82   // Set x = P * b.
     83   cs_di_ipvec(symbolic_factorization->pinv, b, scratch_, A->n);
     84   // Set x = L \ x.
     85   cs_di_lsolve(numeric_factorization->L, scratch_);
     86   // Set x = L' \ x.
     87   cs_di_ltsolve(numeric_factorization->L, scratch_);
     88   // Set b = P' * x.
     89   cs_di_pvec(symbolic_factorization->pinv, scratch_, b, A->n);
     90 
     91   // Free Cholesky factorization.
     92   cs_di_nfree(numeric_factorization);
     93   return true;
     94 }
     95 
     96 cs_dis* CXSparse::AnalyzeCholesky(cs_di* A) {
     97   // order = 1 for Cholesky factorization.
     98   return cs_schol(1, A);
     99 }
    100 
    101 cs_dis* CXSparse::AnalyzeCholeskyWithNaturalOrdering(cs_di* A) {
    102   // order = 0 for Natural ordering.
    103   return cs_schol(0, A);
    104 }
    105 
    106 cs_dis* CXSparse::BlockAnalyzeCholesky(cs_di* A,
    107                                        const vector<int>& row_blocks,
    108                                        const vector<int>& col_blocks) {
    109   const int num_row_blocks = row_blocks.size();
    110   const int num_col_blocks = col_blocks.size();
    111 
    112   vector<int> block_rows;
    113   vector<int> block_cols;
    114   CompressedColumnScalarMatrixToBlockMatrix(A->i,
    115                                             A->p,
    116                                             row_blocks,
    117                                             col_blocks,
    118                                             &block_rows,
    119                                             &block_cols);
    120   cs_di block_matrix;
    121   block_matrix.m = num_row_blocks;
    122   block_matrix.n = num_col_blocks;
    123   block_matrix.nz  = -1;
    124   block_matrix.nzmax = block_rows.size();
    125   block_matrix.p = &block_cols[0];
    126   block_matrix.i = &block_rows[0];
    127   block_matrix.x = NULL;
    128 
    129   int* ordering = cs_amd(1, &block_matrix);
    130   vector<int> block_ordering(num_row_blocks, -1);
    131   copy(ordering, ordering + num_row_blocks, &block_ordering[0]);
    132   cs_free(ordering);
    133 
    134   vector<int> scalar_ordering;
    135   BlockOrderingToScalarOrdering(row_blocks, block_ordering, &scalar_ordering);
    136 
    137   cs_dis* symbolic_factorization =
    138       reinterpret_cast<cs_dis*>(cs_calloc(1, sizeof(cs_dis)));
    139   symbolic_factorization->pinv = cs_pinv(&scalar_ordering[0], A->n);
    140   cs* permuted_A = cs_symperm(A, symbolic_factorization->pinv, 0);
    141 
    142   symbolic_factorization->parent = cs_etree(permuted_A, 0);
    143   int* postordering = cs_post(symbolic_factorization->parent, A->n);
    144   int* column_counts = cs_counts(permuted_A,
    145                                  symbolic_factorization->parent,
    146                                  postordering,
    147                                  0);
    148   cs_free(postordering);
    149   cs_spfree(permuted_A);
    150 
    151   symbolic_factorization->cp = (int*) cs_malloc(A->n+1, sizeof(int));
    152   symbolic_factorization->lnz = cs_cumsum(symbolic_factorization->cp,
    153                                           column_counts,
    154                                           A->n);
    155   symbolic_factorization->unz = symbolic_factorization->lnz;
    156 
    157   cs_free(column_counts);
    158 
    159   if (symbolic_factorization->lnz < 0) {
    160     cs_sfree(symbolic_factorization);
    161     symbolic_factorization = NULL;
    162   }
    163 
    164   return symbolic_factorization;
    165 }
    166 
    167 cs_di CXSparse::CreateSparseMatrixTransposeView(CompressedRowSparseMatrix* A) {
    168   cs_di At;
    169   At.m = A->num_cols();
    170   At.n = A->num_rows();
    171   At.nz = -1;
    172   At.nzmax = A->num_nonzeros();
    173   At.p = A->mutable_rows();
    174   At.i = A->mutable_cols();
    175   At.x = A->mutable_values();
    176   return At;
    177 }
    178 
    179 cs_di* CXSparse::CreateSparseMatrix(TripletSparseMatrix* tsm) {
    180   cs_di_sparse tsm_wrapper;
    181   tsm_wrapper.nzmax = tsm->num_nonzeros();
    182   tsm_wrapper.nz = tsm->num_nonzeros();
    183   tsm_wrapper.m = tsm->num_rows();
    184   tsm_wrapper.n = tsm->num_cols();
    185   tsm_wrapper.p = tsm->mutable_cols();
    186   tsm_wrapper.i = tsm->mutable_rows();
    187   tsm_wrapper.x = tsm->mutable_values();
    188 
    189   return cs_compress(&tsm_wrapper);
    190 }
    191 
    192 void CXSparse::ApproximateMinimumDegreeOrdering(cs_di* A, int* ordering) {
    193   int* cs_ordering = cs_amd(1, A);
    194   copy(cs_ordering, cs_ordering + A->m, ordering);
    195   cs_free(cs_ordering);
    196 }
    197 
    198 cs_di* CXSparse::TransposeMatrix(cs_di* A) {
    199   return cs_di_transpose(A, 1);
    200 }
    201 
    202 cs_di* CXSparse::MatrixMatrixMultiply(cs_di* A, cs_di* B) {
    203   return cs_di_multiply(A, B);
    204 }
    205 
    206 void CXSparse::Free(cs_di* sparse_matrix) {
    207   cs_di_spfree(sparse_matrix);
    208 }
    209 
    210 void CXSparse::Free(cs_dis* symbolic_factorization) {
    211   cs_di_sfree(symbolic_factorization);
    212 }
    213 
    214 }  // namespace internal
    215 }  // namespace ceres
    216 
    217 #endif  // CERES_NO_CXSPARSE
    218