itkRegularStepGradientDescentBaseOptimizer.h

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 *
 *  Copyright Insight Software Consortium
 *
 *  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
 *
 *         http://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 itkRegularStepGradientDescentBaseOptimizer_h
#define itkRegularStepGradientDescentBaseOptimizer_h

#include "itkIntTypes.h"
#include "itkSingleValuedNonLinearOptimizer.h"
#include "ITKOptimizersExport.h"

namespace itk
{
class ITKOptimizers_EXPORT RegularStepGradientDescentBaseOptimizer:
  public SingleValuedNonLinearOptimizer
{
public:
  ITK_DISALLOW_COPY_AND_ASSIGN(RegularStepGradientDescentBaseOptimizer);

  using Self = RegularStepGradientDescentBaseOptimizer;
  using Superclass = SingleValuedNonLinearOptimizer;
  using Pointer = SmartPointer< Self >;
  using ConstPointer = SmartPointer< const Self >;

  itkNewMacro(Self);

  itkTypeMacro(RegularStepGradientDescentBaseOptimizer,
               SingleValuedNonLinearOptimizer);

  typedef enum {
    GradientMagnitudeTolerance = 1,
    StepTooSmall = 2,
    ImageNotAvailable = 3,
    CostFunctionError = 4,
    MaximumNumberOfIterations = 5,
    Unknown = 6
    } StopConditionType;

  itkSetMacro(Maximize, bool);
  itkGetConstReferenceMacro(Maximize, bool);
  itkBooleanMacro(Maximize);
  bool GetMinimize() const
  { return !m_Maximize; }
  void SetMinimize(bool v)
  { this->SetMaximize(!v); }
  void    MinimizeOn()
  { SetMaximize(false); }
  void    MinimizeOff()
  { SetMaximize(true); }

  void    StartOptimization() override;

  void    ResumeOptimization();

  void    StopOptimization();

  itkSetMacro(MaximumStepLength, double);
  itkSetMacro(MinimumStepLength, double);
  itkSetMacro(RelaxationFactor, double);
  itkSetMacro(NumberOfIterations, SizeValueType);
  itkSetMacro(GradientMagnitudeTolerance, double);
  itkGetConstReferenceMacro(CurrentStepLength, double);
  itkGetConstReferenceMacro(MaximumStepLength, double);
  itkGetConstReferenceMacro(MinimumStepLength, double);
  itkGetConstReferenceMacro(RelaxationFactor, double);
  itkGetConstReferenceMacro(NumberOfIterations, SizeValueType);
  itkGetConstReferenceMacro(GradientMagnitudeTolerance, double);
  itkGetConstMacro(CurrentIteration, unsigned int);
  itkGetConstReferenceMacro(StopCondition, StopConditionType);
  itkGetConstReferenceMacro(Value, MeasureType);
  itkGetConstReferenceMacro(Gradient, DerivativeType);

  const std::string GetStopConditionDescription() const override;

protected:
  RegularStepGradientDescentBaseOptimizer();
  ~RegularStepGradientDescentBaseOptimizer() override = default;
  void PrintSelf(std::ostream & os, Indent indent) const override;

  virtual void AdvanceOneStep();

  virtual void StepAlongGradient(
    double,
    const DerivativeType &)
  {
    ExceptionObject ex;

    ex.SetLocation(__FILE__);
    ex.SetDescription("This method MUST be overloaded in derived classes");
    throw ex;
  }

private:
protected:
  DerivativeType m_Gradient;
  DerivativeType m_PreviousGradient;

  bool               m_Stop{false};
  bool               m_Maximize;
  MeasureType        m_Value;
  double             m_GradientMagnitudeTolerance;
  double             m_MaximumStepLength;
  double             m_MinimumStepLength;
  double             m_CurrentStepLength;
  double             m_RelaxationFactor;
  StopConditionType  m_StopCondition;
  SizeValueType      m_NumberOfIterations;
  SizeValueType      m_CurrentIteration;
  std::ostringstream m_StopConditionDescription;
};
} // end namespace itk

#endif