// =========================================================================
// @author Leonardo Florez Valencia
// @email florez-l@javeriana.edu.co
// =========================================================================
#ifndef __fpa__Functors__Dijkstra__Invert__h__
#define __fpa__Functors__Dijkstra__Invert__h__

#include <itkFunctionBase.h>

namespace fpa
{
  namespace Functors
  {
    namespace Dijkstra
    {
      /**
       */
      template< class _TValue >
      class Invert
        : public itk::FunctionBase< _TValue, _TValue >
      {
      public:
        typedef _TValue TValue;
        typedef itk::FunctionBase< _TValue, _TValue > Superclass;
        typedef Invert                                Self;
        typedef itk::SmartPointer< Self >             Pointer;
        typedef itk::SmartPointer< const Self >       ConstPointer;

      public:
        itkNewMacro( Self );
        itkTypeMacro( fpa::Functors::Dijkstra::Invert, itk::FunctionBase );

        itkGetConstMacro( Alpha, double );
        itkSetMacro( Alpha, double );

        itkGetConstMacro( Beta, double );
        itkSetMacro( Beta, double );

      public:
        virtual TValue Evaluate( const TValue& v ) const override
          {
            double a = double( v );
            double d = this->m_Alpha;
            d += std::pow( double( a ), this->m_Beta );
            double x = -1;
            if( std::fabs( d ) > double( 0 ) )
              x =
                double( 1 ) /
                ( this->m_Alpha + std::pow( double( a ), this->m_Beta ) );
            return( TValue( x ) );
          }

      protected:
        Invert( )
          : Superclass( ),
            m_Alpha( double( 1 ) ),
            m_Beta( double( 1 ) )
          {
          }
        virtual ~Invert( )
          {
          }

      private:
        // Purposely not implemented.
        Invert( const Self& other );
        Self& operator=( const Self& other );

      protected:
        double m_Alpha;
        double m_Beta;
      };

    } // ecapseman

  } // ecapseman

} // ecapseman

#endif // __fpa__Functors__Dijkstra__Invert__h__
// eof - $RCSfile$