ITK  4.1.0
Insight Segmentation and Registration Toolkit
itkGaussianKernelFunction.h
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00001 /*=========================================================================
00002  *
00003  *  Copyright Insight Software Consortium
00004  *
00005  *  Licensed under the Apache License, Version 2.0 (the "License");
00006  *  you may not use this file except in compliance with the License.
00007  *  You may obtain a copy of the License at
00008  *
00009  *         http://www.apache.org/licenses/LICENSE-2.0.txt
00010  *
00011  *  Unless required by applicable law or agreed to in writing, software
00012  *  distributed under the License is distributed on an "AS IS" BASIS,
00013  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00014  *  See the License for the specific language governing permissions and
00015  *  limitations under the License.
00016  *
00017  *=========================================================================*/
00018 #ifndef __itkGaussianKernelFunction_h
00019 #define __itkGaussianKernelFunction_h
00020 
00021 #include "itkKernelFunctionBase.h"
00022 #include "vnl/vnl_math.h"
00023 #include <math.h>
00024 
00025 namespace itk
00026 {
00040 template< typename TRealValueType = double >
00041 class ITK_EXPORT GaussianKernelFunction:public KernelFunctionBase<TRealValueType>
00042 {
00043 public:
00045   typedef GaussianKernelFunction             Self;
00046   typedef KernelFunctionBase<TRealValueType> Superclass;
00047   typedef SmartPointer< Self >               Pointer;
00048 
00049   typedef typename Superclass::RealType  RealType;
00051   itkNewMacro(Self);
00052 
00054   itkTypeMacro(GaussianKernelFunction, KernelFunctionBase);
00055 
00057   inline TRealValueType Evaluate(const TRealValueType & u) const
00058   { return ( vcl_exp( static_cast< TRealValueType >(-0.5) * vnl_math_sqr(u) ) * m_Factor ); }
00059 protected:
00060   GaussianKernelFunction(): m_Factor(  NumericTraits< TRealValueType >::One / vcl_sqrt(static_cast< TRealValueType >(2.0 * vnl_math::pi )) ) {};
00061   virtual ~GaussianKernelFunction() {};
00062   void PrintSelf(std::ostream & os, Indent indent) const
00063   { Superclass::PrintSelf(os, indent); }
00064 private:
00065   GaussianKernelFunction(const Self &); //purposely not implemented
00066   void operator=(const Self &);         //purposely not implemented
00068 
00069   const TRealValueType m_Factor;
00070 };
00071 } // end namespace itk
00072 
00073 #endif
00074