Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include "DataContainer.h"
       4             : #include "StrongTypes.h"
       5             : #include "elsaDefines.h"
       6             : 
       7             : namespace elsa
       8             : {
       9             :     /**
      10             :      * @brief Class representing the proximal operator of the l1 norm
      11             :      *
      12             :      * @author Andi Braimllari - initial code
      13             :      *
      14             :      * @tparam data_t data type for the values of the operator, defaulting to real_t
      15             :      *
      16             :      * This class represents the soft thresholding operator, expressed by its apply method through
      17             :      * the function i.e. @f$ prox(v) = sign(v)·(|v| - t)_+. @f$
      18             :      *
      19             :      * References:
      20             :      * http://sfb649.wiwi.hu-berlin.de/fedc_homepage/xplore/tutorials/xlghtmlnode93.html
      21             :      */
      22             :     template <typename data_t = real_t>
      23             :     class ProximalL1
      24             :     {
      25             :     public:
      26          26 :         ProximalL1() = default;
      27             : 
      28             :         explicit ProximalL1(data_t sigma);
      29             : 
      30             :         explicit ProximalL1(const DataContainer<data_t>& b);
      31             : 
      32             :         ProximalL1(const DataContainer<data_t>& b, SelfType_t<data_t> sigma);
      33             : 
      34             :         // default copy constructor
      35          30 :         ProximalL1(const ProximalL1<data_t>&) = default;
      36             : 
      37             :         // default copy assignment
      38             :         ProximalL1& operator=(const ProximalL1<data_t>&) = default;
      39             : 
      40             :         // move constructor
      41             :         ProximalL1(ProximalL1<data_t>&&) noexcept;
      42             : 
      43             :         // move assignment
      44             :         ProximalL1& operator=(ProximalL1<data_t>&&) noexcept;
      45             : 
      46             :         /// default destructor
      47         110 :         ~ProximalL1() = default;
      48             : 
      49             :         /**
      50             :          * @brief apply the proximal operator of the l1 norm to an element in the operator's domain
      51             :          *
      52             :          * @param[in] v input DataContainer
      53             :          * @param[in] t input Threshold
      54             :          * @param[out] prox output DataContainer
      55             :          */
      56             :         void apply(const DataContainer<data_t>& v, SelfType_t<data_t> t,
      57             :                    DataContainer<data_t>& prox) const;
      58             : 
      59             :         DataContainer<data_t> apply(const DataContainer<data_t>& v, SelfType_t<data_t> t) const;
      60             : 
      61             :     private:
      62             :         data_t sigma_{1};
      63             : 
      64             :         std::optional<DataContainer<data_t>> b_ = {};
      65             :     };
      66             : 
      67             :     template <class data_t>
      68             :     using SoftThresholding = ProximalL1<data_t>;
      69             : } // namespace elsa