Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include "DataContainer.h"
       4             : #include "Functional.h"
       5             : 
       6             : namespace elsa
       7             : {
       8             :     /**
       9             :      * @brief Class representing the Huber loss.
      10             :      *
      11             :      * The Huber loss evaluates to \f$ \sum_{i=1}^n \begin{cases} \frac{1}{2} x_i^2 & \text{for }
      12             :      * |x_i| \leq \delta \\ \delta\left(|x_i| - \frac{1}{2}\delta\right) & \text{else} \end{cases}
      13             :      * \f$ for \f$ x=(x_i)_{i=1}^n \f$ and a cut-off parameter \f$ \delta \f$.
      14             :      *
      15             :      * Reference: https://doi.org/10.1214%2Faoms%2F1177703732
      16             :      *
      17             :      * @tparam data_t data type for the domain of the residual of the functional, defaulting to
      18             :      * real_t
      19             :      *
      20             :      * @author
      21             :      * * Matthias Wieczorek - initial code
      22             :      * * Maximilian Hornung - modularization
      23             :      * * Tobias Lasser - modernization
      24             :      *
      25             :      */
      26             :     template <typename data_t = real_t>
      27             :     class Huber : public Functional<data_t>
      28             :     {
      29             :     public:
      30             :         /**
      31             :          * @brief Constructor for the Huber functional, mapping domain vector to scalar (without a
      32             :          * residual)
      33             :          *
      34             :          * @param[in] domainDescriptor describing the domain of the functional
      35             :          * @param[in] delta parameter for linear/square cutoff (defaults to 1e-6)
      36             :          */
      37             :         explicit Huber(const DataDescriptor& domainDescriptor,
      38             :                        real_t delta = static_cast<real_t>(1e-6));
      39             : 
      40             :         /// make copy constructor deletion explicit
      41             :         Huber(const Huber<data_t>&) = delete;
      42             : 
      43             :         /// default destructor
      44          12 :         ~Huber() override = default;
      45             : 
      46             :         bool isDifferentiable() const override;
      47             : 
      48             :     protected:
      49             :         /// the evaluation of the Huber loss
      50             :         data_t evaluateImpl(const DataContainer<data_t>& Rx) const override;
      51             : 
      52             :         /// the computation of the gradient (in place)
      53             :         void getGradientImpl(const DataContainer<data_t>& Rx,
      54             :                              DataContainer<data_t>& out) const override;
      55             : 
      56             :         /// the computation of the Hessian
      57             :         LinearOperator<data_t> getHessianImpl(const DataContainer<data_t>& Rx) const override;
      58             : 
      59             :         /// implement the polymorphic clone operation
      60             :         Huber<data_t>* cloneImpl() const override;
      61             : 
      62             :         /// implement the polymorphic comparison operation
      63             :         bool isEqual(const Functional<data_t>& other) const override;
      64             : 
      65             :     private:
      66             :         /// the cut-off delta
      67             :         data_t delta_;
      68             :     };
      69             : 
      70             : } // namespace elsa