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// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2015 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors may be
// used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Author: sameeragarwal@google.com (Sameer Agarwal)
// keir@google.com (Keir Mierle)
//
// Purpose : Class and struct definitions for parameter and residual blocks.
#ifndef CERES_INTERNAL_RESIDUAL_BLOCK_H_
#define CERES_INTERNAL_RESIDUAL_BLOCK_H_
#include <cstdint>
#include <memory>
#include <string>
#include <vector>
#include "ceres/cost_function.h"
#include "ceres/internal/disable_warnings.h"
#include "ceres/internal/export.h"
#include "ceres/stringprintf.h"
#include "ceres/types.h"
namespace ceres {
class LossFunction;
namespace internal {
class ParameterBlock;
// A term in the least squares problem. The mathematical form of each term in
// the overall least-squares cost function is:
//
// 1
// --- loss_function( || cost_function(block1, block2, ...) ||^2 ),
// 2
//
// Storing the cost function and the loss function separately permits optimizing
// the problem with standard non-linear least techniques, without requiring a
// more general non-linear solver.
//
// The residual block stores pointers to but does not own the cost functions,
// loss functions, and parameter blocks.
class CERES_NO_EXPORT ResidualBlock {
public:
// Construct the residual block with the given cost/loss functions. Loss may
// be null. The index is the index of the residual block in the Program's
// residual_blocks array.
ResidualBlock(const CostFunction* cost_function,
const LossFunction* loss_function,
const std::vector<ParameterBlock*>& parameter_blocks,
int index);
// Evaluates the residual term, storing the scalar cost in *cost, the residual
// components in *residuals, and the jacobians between the parameters and
// residuals in jacobians[i], in row-major order. If residuals is nullptr, the
// residuals are not computed. If jacobians is nullptr, no jacobians are
// computed. If jacobians[i] is nullptr, then the jacobian for that parameter
// is not computed.
//
// cost must not be null.
//
// Evaluate needs scratch space which must be supplied by the caller via
// scratch. The array should have at least NumScratchDoublesForEvaluate()
// space available.
//
// The return value indicates the success or failure. If the function returns
// false, the caller should expect the output memory locations to have
// been modified.
//
// The returned cost and jacobians have had robustification and manifold
// projection applied already; for example, the jacobian for a 4-dimensional
// quaternion parameter using the "Quaternion" manifold is num_residuals by 3
// instead of num_residuals by 4.
//
// apply_loss_function as the name implies allows the user to switch
// the application of the loss function on and off.
bool Evaluate(bool apply_loss_function,
double* cost,
double* residuals,
double** jacobians,
double* scratch) const;
const CostFunction* cost_function() const { return cost_function_; }
const LossFunction* loss_function() const { return loss_function_; }
// Access the parameter blocks for this residual. The array has size
// NumParameterBlocks().
ParameterBlock* const* parameter_blocks() const {
return parameter_blocks_.get();
}
// Number of variable blocks that this residual term depends on.
int NumParameterBlocks() const {
return cost_function_->parameter_block_sizes().size();
}
// The size of the residual vector returned by this residual function.
int NumResiduals() const { return cost_function_->num_residuals(); }
// The minimum amount of scratch space needed to pass to Evaluate().
int NumScratchDoublesForEvaluate() const;
// This residual block's index in an array.
int index() const { return index_; }
void set_index(int index) { index_ = index; }
std::string ToString() const {
return StringPrintf("{residual block; index=%d}", index_);
}
private:
const CostFunction* cost_function_;
const LossFunction* loss_function_;
std::unique_ptr<ParameterBlock*[]> parameter_blocks_;
// The index of the residual, typically in a Program. This is only to permit
// switching from a ResidualBlock* to an index in the Program's array, needed
// to do efficient removals.
int32_t index_;
};
} // namespace internal
} // namespace ceres
#include "ceres/internal/reenable_warnings.h"
#endif // CERES_INTERNAL_RESIDUAL_BLOCK_H_
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