text: /*
   * Copyright (C) 2005-2020 Centre National d'Etudes Spatiales (CNES)
   * Copyright (C) 2007-2012 Institut Mines Telecom / Telecom Bretagne
   *
   * This file is part of Orfeo Toolbox
   *
   *     https://www.orfeo-toolbox.org/
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  
  #ifndef otbSOMLearningBehaviorFunctor_h
  #define otbSOMLearningBehaviorFunctor_h
  
  namespace otb
  {
  
  namespace Functor
  {
  
  /** \class SOMLearningBehaviorFunctor
  * \brief Classical Beta behavior over SOM training phase
  *
  *  This class implements an standard evolution of the \f$ \beta \f$ weightening
  *  coefficient over the SOM training.
  *
  *  \f[
    \beta = \beta_0 + \left( \beta_{\textrm{end}} - \beta_0 \right)
      \frac{t}{t_{\textrm{end}}}
    \f]
  *
  *  \sa SOM
   *
   * \ingroup OTBSOM
  */
  class SOMLearningBehaviorFunctor
  {
  public:
    /** Empty constructor / descructor */
    SOMLearningBehaviorFunctor()
    {
    }
    virtual ~SOMLearningBehaviorFunctor()
    {
    }
  
    /** Functor */
    virtual double operator()(unsigned int currentIteration, unsigned int numberOfIterations, double betaInit, double betaEnd) const
    {
      return betaInit + (betaEnd - betaInit) * static_cast<double>(currentIteration) / static_cast<double>(numberOfIterations);
    }
  
  }; // end of class SOMLearningBehaviorFunctor
  
  } // end namespace Functor
  
  } // end namespace otb
  
  #endif
  