Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include "Functional.h"
       4             : #include "LinearResidual.h"
       5             : 
       6             : namespace elsa
       7             : {
       8             :     /**
       9             :      * @brief Class representing a quadric functional.
      10             :      *
      11             :      * @author Matthias Wieczorek - initial code
      12             :      * @author Maximilian Hornung - modularization
      13             :      * @author Tobias Lasser - modernization
      14             :      * @author Nikola Dinev - add functionality
      15             :      *
      16             :      * @tparam data_t data type for the domain of the residual of the functional, defaulting to
      17             :      * real_t
      18             :      *
      19             :      * The Quadric functional evaluates to \f$ \frac{1}{2} x^tAx - x^tb \f$ for a symmetric positive
      20             :      * definite operator A and a vector b.
      21             :      *
      22             :      * Please note: contrary to other functionals, Quadric does not allow wrapping an explicit
      23             :      * residual.
      24             :      */
      25             :     template <typename data_t = real_t>
      26             :     class Quadric : public Functional<data_t>
      27             :     {
      28             :     public:
      29             :         /**
      30             :          * @brief Constructor for the Quadric functional, using operator A and vector b (no
      31             :          * residual).
      32             :          *
      33             :          * @param[in] A the operator (has to be symmetric positive definite)
      34             :          * @param[in] b the data vector
      35             :          */
      36             :         Quadric(const LinearOperator<data_t>& A, const DataContainer<data_t>& b);
      37             : 
      38             :         /**
      39             :          * @brief Constructor for the Quadric functional \f$ \frac{1}{2} x^tAx \f$ (trivial data
      40             :          * vector)
      41             :          *
      42             :          * @param[in] A the operator (has to be symmetric positive definite)
      43             :          */
      44             :         explicit Quadric(const LinearOperator<data_t>& A);
      45             : 
      46             :         /**
      47             :          * @brief Constructor for the Quadric functional \f$ \frac{1}{2} x^tx - x^tb \f$ (trivial
      48             :          * operator)
      49             :          *
      50             :          * @param[in] b the data vector
      51             :          */
      52             :         explicit Quadric(const DataContainer<data_t>& b);
      53             : 
      54             :         /**
      55             :          * @brief Constructor for the Quadric functional \f$ \frac{1}{2} x^tx \f$ (trivial operator
      56             :          * and data vector)
      57             :          *
      58             :          * @param[in] domainDescriptor the descriptor of x
      59             :          */
      60             :         explicit Quadric(const DataDescriptor& domainDescriptor);
      61             : 
      62             :         /// make copy constructor deletion explicit
      63             :         Quadric(const Quadric<data_t>&) = delete;
      64             : 
      65             :         /// default destructor
      66           0 :         ~Quadric() override = default;
      67             : 
      68             :         /// returns the residual \f$ Ax - b \f$, which also corresponds to the gradient of the
      69             :         /// functional
      70             :         const LinearResidual<data_t>& getGradientExpression() const;
      71             : 
      72             :     protected:
      73             :         /// the evaluation of the Quadric functional
      74             :         data_t evaluateImpl(const DataContainer<data_t>& Rx) override;
      75             : 
      76             :         /// the computation of the gradient (in place)
      77             :         void getGradientInPlaceImpl(DataContainer<data_t>& Rx) override;
      78             : 
      79             :         /// the computation of the Hessian
      80             :         LinearOperator<data_t> getHessianImpl(const DataContainer<data_t>& Rx) override;
      81             : 
      82             :         /// implement the polymorphic clone operation
      83             :         Quadric<data_t>* cloneImpl() const override;
      84             : 
      85             :         /// implement the polymorphic comparison operation
      86             :         bool isEqual(const Functional<data_t>& other) const override;
      87             : 
      88             :     private:
      89             :         /// storing A,b in a linear residual
      90             :         LinearResidual<data_t> _linearResidual;
      91             : 
      92             :         /// lift from base class
      93             :         using Functional<data_t>::_domainDescriptor;
      94             :     };
      95             : 
      96             : } // namespace elsa