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
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28//
29// Author: sameeragarwal@google.com (Sameer Agarwal)
30
31#ifndef CERES_PUBLIC_CRS_MATRIX_H_
32#define CERES_PUBLIC_CRS_MATRIX_H_
33
34#include <vector>
35#include "ceres/internal/port.h"
36
37namespace ceres {
38
39// A compressed row sparse matrix used primarily for communicating the
40// Jacobian matrix to the user.
41struct CRSMatrix {
42  CRSMatrix() : num_rows(0), num_cols(0) {}
43
44  int num_rows;
45  int num_cols;
46
47  // A compressed row matrix stores its contents in three arrays,
48  // rows, cols and values.
49  //
50  // rows is a num_rows + 1 sized array that points into the cols and
51  // values array. For each row i:
52  //
53  // cols[rows[i]] ... cols[rows[i + 1] - 1] are the indices of the
54  // non-zero columns of row i.
55  //
56  // values[rows[i]] .. values[rows[i + 1] - 1] are the values of the
57  // corresponding entries.
58  //
59  // cols and values contain as many entries as there are non-zeros in
60  // the matrix.
61  //
62  // e.g, consider the 3x4 sparse matrix
63  //
64  //  [ 0 10  0  4 ]
65  //  [ 0  2 -3  2 ]
66  //  [ 1  2  0  0 ]
67  //
68  // The three arrays will be:
69  //
70  //
71  //            -row0-  ---row1---  -row2-
72  //  rows   = [ 0,      2,          5,     7]
73  //  cols   = [ 1,  3,  1,  2,  3,  0,  1]
74  //  values = [10,  4,  2, -3,  2,  1,  2]
75
76  vector<int> cols;
77  vector<int> rows;
78  vector<double> values;
79};
80
81}  // namespace ceres
82
83#endif  // CERES_PUBLIC_CRS_MATRIX_H_
84