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//
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6// modification, are permitted provided that the following conditions are met:
7//
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14//   used to endorse or promote products derived from this software without
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16//
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28//
29// Author: keir@google.com (Keir Mierle)
30
31#include "ceres/block_evaluate_preparer.h"
32
33#include <vector>
34#include "ceres/block_sparse_matrix.h"
35#include "ceres/casts.h"
36#include "ceres/parameter_block.h"
37#include "ceres/residual_block.h"
38#include "ceres/sparse_matrix.h"
39
40namespace ceres {
41namespace internal {
42
43void BlockEvaluatePreparer::Init(int const* const* jacobian_layout,
44                                 int max_derivatives_per_residual_block) {
45  jacobian_layout_ = jacobian_layout;
46  scratch_evaluate_preparer_.Init(max_derivatives_per_residual_block);
47}
48
49// Point the jacobian blocks directly into the block sparse matrix.
50void BlockEvaluatePreparer::Prepare(const ResidualBlock* residual_block,
51                                    int residual_block_index,
52                                    SparseMatrix* jacobian,
53                                    double** jacobians) {
54  // If the overall jacobian is not available, use the scratch space.
55  if (jacobian == NULL) {
56    scratch_evaluate_preparer_.Prepare(residual_block,
57                                       residual_block_index,
58                                       jacobian,
59                                       jacobians);
60    return;
61  }
62
63  double* jacobian_values =
64      down_cast<BlockSparseMatrix*>(jacobian)->mutable_values();
65
66  const int* jacobian_block_offset = jacobian_layout_[residual_block_index];
67  const int num_parameter_blocks = residual_block->NumParameterBlocks();
68  for (int j = 0; j < num_parameter_blocks; ++j) {
69    if (!residual_block->parameter_blocks()[j]->IsConstant()) {
70      jacobians[j] = jacobian_values + *jacobian_block_offset;
71
72      // The jacobian_block_offset can't be indexed with 'j' since the code
73      // that creates the layout strips out any blocks for inactive
74      // parameters. Instead, bump the pointer for active parameters only.
75      jacobian_block_offset++;
76    } else {
77      jacobians[j] = NULL;
78    }
79  }
80}
81
82}  // namespace internal
83}  // namespace ceres
84