itkBackPropagationLayer.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 __itkBackPropagationLayer_h
#define __itkBackPropagationLayer_h

#include "itkCompletelyConnectedWeightSet.h"
#include "itkLayerBase.h"
#include "itkObject.h"
#include "itkMacro.h"

namespace itk
{
namespace Statistics
{
template<class TMeasurementVector, class TTargetVector>
class BackPropagationLayer : public LayerBase<TMeasurementVector, TTargetVector>
{
public:
  typedef BackPropagationLayer                         Self;
  typedef LayerBase<TMeasurementVector, TTargetVector> Superclass;
  typedef SmartPointer<Self>                           Pointer;
  typedef SmartPointer<const Self>                     ConstPointer;

  itkTypeMacro(BackPropagationLayer, LayerBase);
  itkNewMacro(Self);

  typedef typename Superclass::ValueType              ValueType;
  typedef vnl_vector<ValueType>                       NodeVectorType;
  typedef typename Superclass::InternalVectorType     InternalVectorType;
  typedef typename Superclass::OutputVectorType       OutputVectorType;
  typedef typename Superclass::LayerInterfaceType     LayerInterfaceType;
  typedef CompletelyConnectedWeightSet<TMeasurementVector,TTargetVector>
                                                      WeightSetType;

  typedef typename Superclass::WeightSetInterfaceType WeightSetInterfaceType;
  typedef typename Superclass::InputFunctionInterfaceType
                                                      InputFunctionInterfaceType;
  typedef typename Superclass::TransferFunctionInterfaceType
                                                      TransferFunctionInterfaceType;
  //Member Functions
  virtual void SetNumberOfNodes(unsigned int numNodes);
  virtual ValueType GetInputValue(unsigned int i) const;
  virtual void SetInputValue(unsigned int i, ValueType value);

  virtual ValueType GetOutputValue(unsigned int) const;
  virtual void SetOutputValue(unsigned int, ValueType);

  virtual ValueType * GetOutputVector();
  void SetOutputVector(TMeasurementVector value);

  virtual void ForwardPropagate();
  virtual void ForwardPropagate(TMeasurementVector input);

  virtual void BackwardPropagate();
  virtual void BackwardPropagate(InternalVectorType errors);

  virtual void SetOutputErrorValues(TTargetVector);
  virtual ValueType GetOutputErrorValue(unsigned int node_id) const;

  virtual ValueType GetInputErrorValue(unsigned int node_id) const;
  virtual ValueType * GetInputErrorVector();
  virtual void SetInputErrorValue(ValueType, unsigned int node_id);

  virtual ValueType Activation(ValueType);
  virtual ValueType DActivation(ValueType);

  itkSetMacro( Bias, ValueType );
  itkGetConstReferenceMacro( Bias, ValueType );

protected:

  BackPropagationLayer();
  virtual ~BackPropagationLayer();

  virtual void PrintSelf( std::ostream& os, Indent indent ) const;

private:

  NodeVectorType   m_NodeInputValues;
  NodeVectorType   m_NodeOutputValues;
  NodeVectorType   m_InputErrorValues;
  NodeVectorType   m_OutputErrorValues;
  ValueType        m_Bias;
};

} // end namespace Statistics
} // end namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkBackPropagationLayer.hxx"
#endif

#endif