// =========================================================================
// @author Leonardo Florez Valencia
// @email florez-l@javeriana.edu.co
// =========================================================================

#ifndef __fpa__Image__Functors__Dijkstra__Gaussian__h__
#define __fpa__Image__Functors__Dijkstra__Gaussian__h__

#include <cmath>
#include <fpa/Image/Functors/Dijkstra/Function.h>

namespace fpa
{
  namespace Image
  {
    namespace Functors
    {
      namespace Dijkstra
      {
        /**
         * w_{i,j}=\left(\exp\left(\left(\frac{w_{i}-w_{j}}{\beta}\right)^{2}\right)-1\right)^{\alpha}
         */
        template< class _TInputImage, class _TOutputValue >
        class Gaussian
          : public fpa::Image::Functors::Dijkstra::Function< _TInputImage, _TOutputValue >
        {
        public:
          typedef Gaussian Self;
          typedef fpa::Image::Functors::Dijkstra::Function< _TInputImage, _TOutputValue > Superclass;
          typedef itk::SmartPointer< Self >       Pointer;
          typedef itk::SmartPointer< const Self > ConstPointer;

          typedef typename Superclass::TVertex TVertex;

        public:
          itkNewMacro( Self );
          itkTypeMacro(
            fpa::Image::Functors::Dijkstra::Gaussian,
            fpa::Image::Functors::Dijkstra::Function
            );

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

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

        public:
          virtual _TOutputValue Evaluate(
            const TVertex& v, const TVertex& p
            ) const override
            {
              double d = double( this->m_Image->GetPixel( v ) );
              d       -= double( this->m_Image->GetPixel( p ) );
              d       /= this->m_Beta;
              d = std::exp( d * d ) - double( 1 );
              return( _TOutputValue( std::pow( d, this->m_Alpha ) ) );
            }

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

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

        protected:
          double m_Alpha;
          double m_Beta;
        };

      } // ecapseman

    } // ecapseman

  } // ecapseman

} // ecapseman

#endif // __fpa__Image__Functors__Dijkstra__Gaussian__h__

// eof - $RCSfile$