Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include "Functional.h"
       4             : 
       5             : namespace elsa
       6             : {
       7             :     /**
       8             :      * @brief Class representing the Huber norm.
       9             :      *
      10             :      * @author Matthias Wieczorek - initial code
      11             :      * @author Maximilian Hornung - modularization
      12             :      * @author Tobias Lasser - modernization
      13             :      *
      14             :      * @tparam data_t data type for the domain of the residual of the functional, defaulting to
      15             :      * real_t
      16             :      *
      17             :      * The Huber norm evaluates to \f$ \sum_{i=1}^n \begin{cases} \frac{1}{2} x_i^2 & \text{for }
      18             :      * |x_i| \leq \delta \\ \delta\left(|x_i| - \frac{1}{2}\delta\right) & \text{else} \end{cases}
      19             :      * \f$ for \f$ x=(x_i)_{i=1}^n \f$ and a cut-off parameter \f$ \delta \f$.
      20             :      *
      21             :      * Reference: https://doi.org/10.1214%2Faoms%2F1177703732
      22             :      */
      23             :     template <typename data_t = real_t>
      24             :     class Huber : public Functional<data_t>
      25             :     {
      26             :     public:
      27             :         /**
      28             :          * @brief Constructor for the Huber functional, mapping domain vector to scalar (without a
      29             :          * residual)
      30             :          *
      31             :          * @param[in] domainDescriptor describing the domain of the functional
      32             :          * @param[in] delta parameter for linear/square cutoff (defaults to 1e-6)
      33             :          */
      34             :         explicit Huber(const DataDescriptor& domainDescriptor,
      35             :                        real_t delta = static_cast<real_t>(1e-6));
      36             : 
      37             :         /**
      38             :          * @brief Constructor for the Huber functional, using a residual as input to map to a scalar
      39             :          *
      40             :          * @param[in] residual to be used when evaluating the functional (or its derivative)
      41             :          * @param[in] delta parameter for linear/square cutoff (defaults to 1e-6)
      42             :          */
      43             :         explicit Huber(const Residual<data_t>& residual, real_t delta = static_cast<real_t>(1e-6));
      44             : 
      45             :         /// make copy constructor deletion explicit
      46             :         Huber(const Huber<data_t>&) = delete;
      47             : 
      48             :         /// default destructor
      49           0 :         ~Huber() override = default;
      50             : 
      51             :     protected:
      52             :         /// the evaluation of the Huber norm
      53             :         data_t evaluateImpl(const DataContainer<data_t>& Rx) override;
      54             : 
      55             :         /// the computation of the gradient (in place)
      56             :         void getGradientInPlaceImpl(DataContainer<data_t>& Rx) override;
      57             : 
      58             :         /// the computation of the Hessian
      59             :         LinearOperator<data_t> getHessianImpl(const DataContainer<data_t>& Rx) override;
      60             : 
      61             :         /// implement the polymorphic clone operation
      62             :         Huber<data_t>* cloneImpl() const override;
      63             : 
      64             :         /// implement the polymorphic comparison operation
      65             :         bool isEqual(const Functional<data_t>& other) const override;
      66             : 
      67             :     private:
      68             :         /// the cut-off delta
      69             :         const real_t _delta;
      70             :     };
      71             : 
      72             : } // namespace elsa