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

#ifndef __fpa__Base__Functors__InvertValue__h__
#define __fpa__Base__Functors__InvertValue__h__

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

namespace fpa
{
  namespace Base
  {
    namespace Functors
    {
      /**
       */
      template< class _TInputValue, class _TOutputValue >
      class InvertValue
        : public itk::FunctionBase< _TInputValue, _TOutputValue >
      {
      public:
        typedef InvertValue                                      Self;
        typedef itk::FunctionBase< _TInputValue, _TOutputValue > Superclass;
        typedef itk::SmartPointer< Self >                        Pointer;
        typedef itk::SmartPointer< const Self >                  ConstPointer;

        typedef _TInputValue  TInputValue;
        typedef _TOutputValue TOutputValue;

      public:
        itkNewMacro( Self );
        itkTypeMacro( InvertValue, itk::FunctionBase );

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

      public:
        virtual TOutputValue Evaluate( const TInputValue& a ) const override
          {
            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( TOutputValue( x ) );
          }

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

      private:
        InvertValue( const Self& other );
        Self& operator=( const Self& other );

      protected:
        double m_Alpha;
        double m_Beta;
      };

    } // ecapseman

  } // ecapseman

} // ecapseman

#endif // __fpa__Base__Functors__InvertValue__h__

// eof - $RCSfile$