#ifndef __FPA__BASE__FUNCTORS__INVERTCOSTFUNCTION__H__
#define __FPA__BASE__FUNCTORS__INVERTCOSTFUNCTION__H__

#include <cmath>
#include <itkFunctionBase.h>

namespace fpa
{
  namespace Base
  {
    namespace Functors
    {
      /**
       */
      template< class C >
      class InvertCostFunction
        : public itk::FunctionBase< C, C >
      {
      public:
        /// Type-related and pointers
        typedef InvertCostFunction              Self;
        typedef itk::FunctionBase< C, C >       Superclass;
        typedef itk::SmartPointer< Self >       Pointer;
        typedef itk::SmartPointer< const Self > ConstPointer;

      public:
        itkNewMacro( Self );
        itkTypeMacro( InvertCostFunction, itkFunctionBase );

        itkGetConstMacro( Alpha, C );
        itkGetConstMacro( Beta, C );

        itkSetMacro( Alpha, C );
        itkSetMacro( Beta, C );

      public:
        virtual C Evaluate( const C& input ) const ITK_OVERRIDE
          {
            C a = std::pow( input, this->m_Alpha );
            if( input >= C( 0 ) )
              return( std::pow( C( 1 ) / ( C( 1 ) + a ), this->m_Beta ) );
            else
              return( std::pow( C( -1 ) / ( C( 1 ) - a ), this->m_Beta ) );
          }

      protected:
        InvertCostFunction( )
          : Superclass( ),
            m_Alpha( C( 1 ) ),
            m_Beta( C( 1 ) )
          { }
        virtual ~InvertCostFunction( )
          { }

      private:
        // Purposely not implemented
        InvertCostFunction( const Self& );
        void operator=( const Self& );

      protected:
        C m_Alpha;
        C m_Beta;
      };

    } // ecapseman

  } // ecapseman

} // ecapseman

#endif // __FPA__BASE__FUNCTORS__INVERTCOSTFUNCTION__H__

// eof - $RCSfile$