text: /*=========================================================================
   *
   *  Copyright NumFOCUS
   *
   *  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
   *
   *         https://www.apache.org/licenses/LICENSE-2.0.txt
   *
   *  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 itkHeavisideStepFunction_hxx
  #define itkHeavisideStepFunction_hxx
  
  #include "itkMath.h"
  
  namespace itk
  {
  template <typename TInput, typename TOutput>
  HeavisideStepFunction<TInput, TOutput>::HeavisideStepFunction()
    : Superclass()
  {}
  
  template <typename TInput, typename TOutput>
  auto
  HeavisideStepFunction<TInput, TOutput>::Evaluate(const InputType & input) const -> OutputType
  {
    return (input >= NumericTraits<InputType>::ZeroValue()) ? NumericTraits<OutputType>::OneValue()
                                                            : NumericTraits<OutputType>::ZeroValue();
  }
  
  template <typename TInput, typename TOutput>
  auto
  HeavisideStepFunction<TInput, TOutput>::EvaluateDerivative(const InputType & input) const -> OutputType
  {
    return (Math::ExactlyEquals(input, NumericTraits<InputType>::ZeroValue())) ? NumericTraits<OutputType>::OneValue()
                                                                               : NumericTraits<OutputType>::ZeroValue();
  }
  
  } // namespace itk
  
  #endif // itkHeavisideStepFunction_hxx
  