text: /*=========================================================================
   *
   *  Copyright NumFOCUS
   *
   *  Licensed under the Apache License, Version 2.0 (the "License");
   *  you may not use this file except in compliance with the License.
   *  You may obtain a copy of the License at
   *
   *         https://www.apache.org/licenses/LICENSE-2.0.txt
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   *
   *=========================================================================*/
  #ifndef itkSingleValuedNonLinearVnlOptimizer_h
  #define itkSingleValuedNonLinearVnlOptimizer_h
  
  #include "itkSingleValuedNonLinearOptimizer.h"
  #include "itkSingleValuedVnlCostFunctionAdaptor.h"
  #include "itkCommand.h"
  #include "ITKOptimizersExport.h"
  
  namespace itk
  {
  /** \class SingleValuedNonLinearVnlOptimizer
   * \brief This class is a base for the Optimization methods that
   * optimize a single valued function.
   *
   * It is an Adaptor class for optimizers provided by the vnl library
   *
   * \ingroup Numerics Optimizers
   * \ingroup ITKOptimizers
   */
  class ITKOptimizers_EXPORT SingleValuedNonLinearVnlOptimizer : public SingleValuedNonLinearOptimizer
  {
  public:
    ITK_DISALLOW_COPY_AND_MOVE(SingleValuedNonLinearVnlOptimizer);
  
    /** Standard class type aliases. */
    using Self = SingleValuedNonLinearVnlOptimizer;
    using Superclass = SingleValuedNonLinearOptimizer;
    using Pointer = SmartPointer<Self>;
    using ConstPointer = SmartPointer<const Self>;
  
    /** Run-time type information (and related methods). */
    itkTypeMacro(SingleValuedNonLinearVnlOptimizer, SingleValueNonLinearOptimizer);
  
    /** Command observer that will interact with the ITKVNL cost-function
     * adaptor in order to generate iteration events. This will allow to overcome
     * the limitation of VNL optimizers not offering callbacks for every
     * iteration */
    using CommandType = ReceptorMemberCommand<Self>;
  
    /** Set the cost Function. This method has to be overloaded
     *  by derived classes because the CostFunctionAdaptor requires
     *  to know the number of parameters at construction time. This
     *  number of parameters is obtained at run-time from the itkCostFunction.
     *  As a consequence each derived optimizer should construct its own
     *  CostFunctionAdaptor when overloading this method  */
    void
    SetCostFunction(SingleValuedCostFunction * costFunction) override = 0;
  
    /** Methods to define whether the cost function will be maximized or
     * minimized. By default the VNL amoeba optimizer is only a minimizer.
     * Maximization is implemented here by notifying the CostFunctionAdaptor
     * which in its turn will multiply the function values and its derivative by
     * -1.0. */
    itkGetConstReferenceMacro(Maximize, bool);
    itkSetMacro(Maximize, bool);
    itkBooleanMacro(Maximize);
    bool
    GetMinimize() const
    {
      return !m_Maximize;
    }
    void
    SetMinimize(bool v)
    {
      this->SetMaximize(!v);
    }
    void
    MinimizeOn()
    {
      this->MaximizeOff();
    }
    void
    MinimizeOff()
    {
      this->MaximizeOn();
    }
  
    /** Return Cached Values. These method have the advantage of not triggering a
     * recomputation of the metric value, but it has the disadvantage of returning
     * a value that may not be the one corresponding to the current parameters. For
     * GUI update purposes, this method is a good option, for mathematical
     * validation you should rather call GetValue(). */
    itkGetConstReferenceMacro(CachedValue, MeasureType);
    itkGetConstReferenceMacro(CachedDerivative, DerivativeType);
    itkGetConstReferenceMacro(CachedCurrentPosition, ParametersType);
  
  protected:
    SingleValuedNonLinearVnlOptimizer();
    ~SingleValuedNonLinearVnlOptimizer() override;
  
    using CostFunctionAdaptorType = SingleValuedVnlCostFunctionAdaptor;
  
    void
    SetCostFunctionAdaptor(CostFunctionAdaptorType * adaptor);
  
    const CostFunctionAdaptorType *
    GetCostFunctionAdaptor() const;
  
    CostFunctionAdaptorType *
    GetCostFunctionAdaptor();
  
    /** The purpose of this method is to get around the lack of
     *  const-correctness in VNL cost-functions and optimizers */
    CostFunctionAdaptorType *
    GetNonConstCostFunctionAdaptor() const;
  
    /** Print out internal state */
    void
    PrintSelf(std::ostream & os, Indent indent) const override;
  
  private:
    /** Callback function for the Command Observer */
    void
    IterationReport(const EventObject & event);
  
    CostFunctionAdaptorType * m_CostFunctionAdaptor;
  
    bool m_Maximize;
  
    CommandType::Pointer m_Command;
  
    mutable ParametersType m_CachedCurrentPosition;
    mutable MeasureType    m_CachedValue;
    mutable DerivativeType m_CachedDerivative;
  };
  } // end namespace itk
  
  #endif
  