| // Ceres Solver - A fast non-linear least squares minimizer |
| // Copyright 2017 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 |
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| // POSSIBILITY OF SUCH DAMAGE. |
| // |
| // Author: sameeragarwal@google.com (Sameer Agarwal) |
| // keir@google.m (Keir Mierle) |
| // |
| // This is the interface through which the least squares solver accesses the |
| // residual and Jacobian of the least squares problem. Users are expected to |
| // subclass CostFunction to define their own terms in the least squares problem. |
| // |
| // It is recommended that users define templated residual functors for use as |
| // arguments for AutoDiffCostFunction (see autodiff_cost_function.h), instead of |
| // directly implementing the CostFunction interface. This often results in both |
| // shorter code and faster execution than hand-coded derivatives. However, |
| // specialized cases may demand direct implementation of the lower-level |
| // CostFunction interface; for example, this is true when calling legacy code |
| // which is not templated on numeric types. |
| |
| #ifndef CERES_PUBLIC_COST_FUNCTION_H_ |
| #define CERES_PUBLIC_COST_FUNCTION_H_ |
| |
| #include <vector> |
| #include "ceres/internal/macros.h" |
| #include "ceres/internal/port.h" |
| #include "ceres/types.h" |
| #include "ceres/internal/disable_warnings.h" |
| |
| namespace ceres { |
| |
| // This class implements the computation of the cost (a.k.a. residual) terms as |
| // a function of the input (control) variables, and is the interface for users |
| // to describe their least squares problem to Ceres. In other words, this is the |
| // modeling layer between users and the Ceres optimizer. The signature of the |
| // function (number and sizes of input parameter blocks and number of outputs) |
| // is stored in parameter_block_sizes_ and num_residuals_ respectively. User |
| // code inheriting from this class is expected to set these two members with the |
| // corresponding accessors. This information will be verified by the Problem |
| // when added with AddResidualBlock(). |
| class CERES_EXPORT CostFunction { |
| public: |
| CostFunction() : num_residuals_(0) {} |
| |
| virtual ~CostFunction() {} |
| |
| // Inputs: |
| // |
| // parameters is an array of pointers to arrays containing the |
| // various parameter blocks. parameters has the same number of |
| // elements as parameter_block_sizes_. Parameter blocks are in the |
| // same order as parameter_block_sizes_.i.e., |
| // |
| // parameters_[i] = double[parameter_block_sizes_[i]] |
| // |
| // Outputs: |
| // |
| // residuals is an array of size num_residuals_. |
| // |
| // jacobians is an array of size parameter_block_sizes_ containing |
| // pointers to storage for jacobian blocks corresponding to each |
| // parameter block. Jacobian blocks are in the same order as |
| // parameter_block_sizes, i.e. jacobians[i], is an |
| // array that contains num_residuals_* parameter_block_sizes_[i] |
| // elements. Each jacobian block is stored in row-major order, i.e., |
| // |
| // jacobians[i][r*parameter_block_size_[i] + c] = |
| // d residual[r] / d parameters[i][c] |
| // |
| // If jacobians is NULL, then no derivatives are returned; this is |
| // the case when computing cost only. If jacobians[i] is NULL, then |
| // the jacobian block corresponding to the i'th parameter block must |
| // not to be returned. |
| // |
| // The return value indicates whether the computation of the |
| // residuals and/or jacobians was successful or not. |
| // |
| // This can be used to communicate numerical failures in jacobian |
| // computations for instance. |
| // |
| // A more interesting and common use is to impose constraints on the |
| // parameters. If the initial values of the parameter blocks satisfy |
| // the constraints, then returning false whenever the constraints |
| // are not satisfied will prevent the solver from moving into the |
| // infeasible region. This is not a very sophisticated mechanism for |
| // enforcing constraints, but is often good enough. |
| // |
| // Note that it is important that the initial values of the |
| // parameter block must be feasible, otherwise the solver will |
| // declare a numerical problem at iteration 0. |
| virtual bool Evaluate(double const* const* parameters, |
| double* residuals, |
| double** jacobians) const = 0; |
| |
| const std::vector<int32>& parameter_block_sizes() const { |
| return parameter_block_sizes_; |
| } |
| |
| int num_residuals() const { |
| return num_residuals_; |
| } |
| |
| protected: |
| std::vector<int32>* mutable_parameter_block_sizes() { |
| return ¶meter_block_sizes_; |
| } |
| |
| void set_num_residuals(int num_residuals) { |
| num_residuals_ = num_residuals; |
| } |
| |
| private: |
| // Cost function signature metadata: number of inputs & their sizes, |
| // number of outputs (residuals). |
| std::vector<int32> parameter_block_sizes_; |
| int num_residuals_; |
| CERES_DISALLOW_COPY_AND_ASSIGN(CostFunction); |
| }; |
| |
| } // namespace ceres |
| |
| #include "ceres/internal/reenable_warnings.h" |
| |
| #endif // CERES_PUBLIC_COST_FUNCTION_H_ |