/usr/include/InsightToolkit/Common/itkBSplineKernelFunction.h is in libinsighttoolkit3-dev 3.20.1-1.
This file is owned by root:root, with mode 0o644.
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Program: Insight Segmentation & Registration Toolkit
Module: itkBSplineKernelFunction.h
Language: C++
Date: $Date$
Version: $Revision$
Copyright (c) Insight Software Consortium. All rights reserved.
See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notices for more information.
=========================================================================*/
#ifndef __itkBSplineKernelFunction_h
#define __itkBSplineKernelFunction_h
#include "itkKernelFunction.h"
#include "vnl/vnl_math.h"
namespace itk
{
/** \class BSplineKernelFunction
* \brief BSpline kernel used for density estimation and nonparameteric
* regression.
*
* This class enscapsulates BSpline kernel for
* density estimation or nonparameteric regression.
* See documentation for KernelFunction for more details.
*
* This class is templated over the spline order.
* \warning Evaluate is only implemented for spline order 0 to 3
*
* \sa KernelFunction
*
* \ingroup Functions
*/
template <unsigned int VSplineOrder = 3>
class ITK_EXPORT BSplineKernelFunction : public KernelFunction
{
public:
/** Standard class typedefs. */
typedef BSplineKernelFunction Self;
typedef KernelFunction Superclass;
typedef SmartPointer<Self> Pointer;
/** Method for creation through the object factory. */
itkNewMacro(Self);
/** Run-time type information (and related methods). */
itkTypeMacro(BSplineKernelFunction, KernelFunction);
/** Enum of for spline order. */
itkStaticConstMacro(SplineOrder, unsigned int, VSplineOrder);
/** Evaluate the function. */
inline double Evaluate( const double & u ) const
{
return this->Evaluate( Dispatch<VSplineOrder>(), u );
}
protected:
BSplineKernelFunction(){};
~BSplineKernelFunction(){};
void PrintSelf(std::ostream& os, Indent indent) const
{
Superclass::PrintSelf( os, indent );
os << indent << "Spline Order: " << SplineOrder << std::endl;
}
private:
BSplineKernelFunction(const Self&); //purposely not implemented
void operator=(const Self&); //purposely not implemented
/** Structures to control overloaded versions of Evaluate */
struct DispatchBase {};
template<unsigned int>
struct Dispatch : DispatchBase {};
/** Zeroth order spline. */
inline double Evaluate (const Dispatch<0>&, const double & u) const
{
double absValue = vnl_math_abs( u );
if ( absValue < 0.5 )
{
return 1.0;
}
else if ( absValue == 0.5 )
{
return 0.5;
}
else
{
return 0.0;
}
}
/** First order spline */
inline double Evaluate ( const Dispatch<1>&, const double& u) const
{
double absValue = vnl_math_abs( u );
if ( absValue < 1.0 )
{
return 1.0 - absValue;
}
else
{
return 0.0;
}
}
/** Second order spline. */
inline double Evaluate ( const Dispatch<2>&, const double& u) const
{
double absValue = vnl_math_abs( u );
if ( absValue < 0.5 )
{
return 0.75 - vnl_math_sqr( absValue );
}
else if ( absValue < 1.5 )
{
return ( 9.0 - 12.0 * absValue + 4.0 * vnl_math_sqr( absValue ) ) / 8.0;
}
else
{
return 0.0;
}
}
/** Third order spline. */
inline double Evaluate ( const Dispatch<3>&, const double& u) const
{
double absValue = vnl_math_abs( u );
double sqrValue = vnl_math_sqr( u );
if ( absValue < 1.0 )
{
return ( 4.0 - 6.0 * sqrValue + 3.0 * sqrValue * absValue ) / 6.0;
}
else if ( absValue < 2.0 )
{
return ( 8.0 - 12 * absValue + 6.0 * sqrValue -
sqrValue * absValue ) / 6.0;
}
else
{
return 0.0;
}
}
/** Unimplemented spline order */
inline double Evaluate ( const DispatchBase&, const double&) const
{
itkExceptionMacro("Evaluate not implemented for spline\
order " << SplineOrder);
return 0.0; // This is to avoid compiler warning about missing
// return statement. It should never be evaluated.
}
};
} // end namespace itk
#endif
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