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:
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16//
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28//
29// Author: keir@google.com (Keir Mierle)
30
31#include "ceres/scratch_evaluate_preparer.h"
32
33#include "ceres/parameter_block.h"
34#include "ceres/program.h"
35#include "ceres/residual_block.h"
36
37namespace ceres {
38namespace internal {
39
40ScratchEvaluatePreparer* ScratchEvaluatePreparer::Create(
41    const Program &program,
42    int num_threads) {
43  ScratchEvaluatePreparer* preparers = new ScratchEvaluatePreparer[num_threads];
44  int max_derivatives_per_residual_block =
45      program.MaxDerivativesPerResidualBlock();
46  for (int i = 0; i < num_threads; i++) {
47    preparers[i].Init(max_derivatives_per_residual_block);
48  }
49  return preparers;
50}
51
52void ScratchEvaluatePreparer::Init(int max_derivatives_per_residual_block) {
53  jacobian_scratch_.reset(
54      new double[max_derivatives_per_residual_block]);
55}
56
57// Point the jacobian blocks into the scratch area of this evaluate preparer.
58void ScratchEvaluatePreparer::Prepare(const ResidualBlock* residual_block,
59                                      int /* residual_block_index */,
60                                      SparseMatrix* /* jacobian */,
61                                      double** jacobians) {
62  double* jacobian_block_cursor = jacobian_scratch_.get();
63  int num_residuals = residual_block->NumResiduals();
64  int num_parameter_blocks = residual_block->NumParameterBlocks();
65  for (int j = 0; j < num_parameter_blocks; ++j) {
66    const ParameterBlock* parameter_block =
67        residual_block->parameter_blocks()[j];
68    if (parameter_block->IsConstant()) {
69      jacobians[j] = NULL;
70    } else {
71      jacobians[j] = jacobian_block_cursor;
72      jacobian_block_cursor += num_residuals * parameter_block->LocalSize();
73    }
74  }
75}
76
77}  // namespace internal
78}  // namespace ceres
79