00001 /*========================================================================= 00002 00003 Program: Insight Segmentation & Registration Toolkit 00004 Module: $RCSfile: itkSinRegularizedHeavisideStepFunction.h,v $ 00005 Language: C++ 00006 Date: $Date: 2009-06-08 04:17:06 $ 00007 Version: $Revision: 1.3 $ 00008 00009 Copyright (c) Insight Software Consortium. All rights reserved. 00010 See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details. 00011 00012 This software is distributed WITHOUT ANY WARRANTY; without even 00013 the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 00014 PURPOSE. See the above copyright notices for more information. 00015 00016 =========================================================================*/ 00017 00018 #ifndef __itkSinRegularizedHeavisideStepFunction_h 00019 #define __itkSinRegularizedHeavisideStepFunction_h 00020 00021 #include "itkRegularizedHeavisideStepFunction.h" 00022 00023 namespace itk 00024 { 00025 00052 template< class TInput = float, class TOutput = double > 00053 class SinRegularizedHeavisideStepFunction : 00054 public RegularizedHeavisideStepFunction< TInput, TOutput > 00055 { 00056 public: 00057 typedef SinRegularizedHeavisideStepFunction Self; 00058 typedef RegularizedHeavisideStepFunction< TInput, TOutput > Superclass; 00059 typedef SmartPointer<Self> Pointer; 00060 typedef SmartPointer<const Self> ConstPointer; 00061 00062 itkNewMacro( Self ); 00063 00064 itkTypeMacro( SinRegularizedHeavisideStepFunction, RegularizedHeavisideStepFunction ); 00065 00066 typedef typename Superclass::InputType InputType; 00067 typedef typename Superclass::OutputType OutputType; 00068 typedef typename Superclass::RealType RealType; 00069 00071 virtual OutputType Evaluate( const InputType& input ) const 00072 { 00073 if( input >= this->GetEpsilon() ) 00074 { 00075 return 1.0; 00076 } 00077 else 00078 { 00079 if( input <= -this->GetEpsilon() ) 00080 { 00081 return 0.0; 00082 } 00083 else 00084 { 00085 const RealType angleFactor = 0.5 * vnl_math::pi * this->GetOneOverEpsilon(); 00086 const RealType angle = input * angleFactor; 00087 return 0.5 * ( 1.0 + vcl_sin( angle ) ); 00088 } 00089 } 00090 } 00092 00094 virtual OutputType EvaluateDerivative( const InputType& input ) const 00095 { 00096 if( vnl_math_abs( input ) >= this->GetEpsilon() ) 00097 { 00098 return 0.0; 00099 } 00100 else 00101 { 00102 const RealType angleFactor = 0.5 * vnl_math::pi * this->GetOneOverEpsilon(); 00103 const RealType angle = input * angleFactor; 00104 return 0.5 * angleFactor * vcl_cos( angle ); 00105 } 00106 } 00108 00109 protected: 00110 SinRegularizedHeavisideStepFunction() {} 00111 virtual ~SinRegularizedHeavisideStepFunction() {} 00112 00113 private: 00114 SinRegularizedHeavisideStepFunction(const Self& ); //purposely not implemented 00115 void operator=(const Self& ); //purposely not implemented 00116 00117 }; 00118 00119 } 00120 00121 #endif 00122