itkGaussianMembershipFunction.h

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/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkGaussianMembershipFunction.h,v $
  Language:  C++
  Date:      $Date: 2009-05-02 05:43:55 $
  Version:   $Revision: 1.1 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef __itkGaussianMembershipFunction_h
#define __itkGaussianMembershipFunction_h

#include "itkArray.h"
#include "itkMatrix.h"
#include "itkMembershipFunctionBase.h"

namespace itk { 
namespace Statistics {

template< class TMeasurementVector >
class ITK_EXPORT GaussianMembershipFunction :
    public MembershipFunctionBase< TMeasurementVector >
{
public:
  typedef GaussianMembershipFunction                    Self;
  typedef MembershipFunctionBase< TMeasurementVector >  Superclass;
  typedef SmartPointer<Self>                            Pointer;
  typedef SmartPointer<const Self>                      ConstPointer;

  itkTypeMacro(GaussianMembershipFunction, MembershipFunction);
  itkNewMacro(Self);

  typedef TMeasurementVector MeasurementVectorType;

  typedef typename Superclass::MeasurementVectorSizeType MeasurementVectorSizeType;

  typedef Array< double >                               MeanType;

  typedef VariableSizeMatrix< double >                  CovarianceType;

  void SetMean( const MeanType & mean );
  itkGetConstMacro( Mean, MeanType );

  void SetCovariance(const CovarianceType & cov); 
  itkGetConstMacro( Covariance, CovarianceType ); 

  double Evaluate(const MeasurementVectorType &measurement) const;

  Pointer Clone(); 

protected:
  GaussianMembershipFunction(void);
  virtual ~GaussianMembershipFunction(void) {}
  void PrintSelf(std::ostream& os, Indent indent) const;

private:
  MeanType        m_Mean;           // mean
  CovarianceType  m_Covariance;     // covariance matrix

  // inverse covariance matrix which is automatically calculated 
  // when covariace matirx is set.  This speed up the GetProbability()
  CovarianceType  m_InverseCovariance; 

  // pre_factor which is automatically calculated 
  // when covariace matirx is set.  This speeds up the GetProbability()  
  double m_PreFactor;

  bool m_IsCovarianceZero;
};

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

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkGaussianMembershipFunction.txx"
#endif

#endif

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