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STYLE: Prefer compile-time constexpr #5110

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merged 3 commits into from
Dec 30, 2024
Merged

STYLE: Prefer compile-time constexpr #5110

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8f5f9b1
STYLE: Prefer compile-time constexpr
hjmjohnson Dec 22, 2024
3ca7ee5
STYLE: Move static constexpr to local scope where needed
hjmjohnson Dec 27, 2024
1e0de79
STYLE: Prefer static member function Sinc
hjmjohnson Dec 27, 2024
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59 changes: 25 additions & 34 deletions Modules/Core/ImageFunction/include/itkWindowedSincInterpolateImageFunction.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@

namespace itk
{
// clang-format off
namespace Function
{
/**
Expand All @@ -41,12 +42,10 @@ class ITK_TEMPLATE_EXPORT CosineWindowFunction
inline TOutput
operator()(const TInput & A) const
{
return static_cast<TOutput>(std::cos(A * m_Factor));
/** Equal to \f$ \frac{\pi}{2 m} \f$ */
static constexpr double factor = Math::pi / (2 * VRadius);
return static_cast<TOutput>(std::cos(A * factor));
}

private:
/** Equal to \f$ \frac{\pi}{2 m} \f$ */
static const double m_Factor;
};

/**
Expand All @@ -63,12 +62,10 @@ class ITK_TEMPLATE_EXPORT HammingWindowFunction
inline TOutput
operator()(const TInput & A) const
{
return static_cast<TOutput>(0.54 + 0.46 * std::cos(A * m_Factor));
/** Equal to \f$ \frac{\pi}{m} \f$ */
static constexpr double factor = Math::pi / VRadius;
return static_cast<TOutput>(0.54 + 0.46 * std::cos(A * factor));
}

private:
/** Equal to \f$ \frac{\pi}{m} \f$ */
static const double m_Factor;
};

/**
Expand All @@ -85,12 +82,10 @@ class ITK_TEMPLATE_EXPORT WelchWindowFunction
inline TOutput
operator()(const TInput & A) const
{
return static_cast<TOutput>(1.0 - A * m_Factor * A);
/** Equal to \f$ \frac{1}{m^2} \f$ */
static constexpr double factor = 1.0 / (VRadius * VRadius);
return static_cast<TOutput>(1.0 - A * factor * A);
}

private:
/** Equal to \f$ \frac{1}{m^2} \f$ */
static const double m_Factor;
};

/**
Expand All @@ -112,14 +107,12 @@ class ITK_TEMPLATE_EXPORT LanczosWindowFunction
if (A == 0.0)
{
return static_cast<TOutput>(1.0);
}
const double z = m_Factor * A;
} // namespace Function
/** Equal to \f$ \frac{\pi}{m} \f$ */
static constexpr double factor = Math::pi / VRadius;
const double z = factor * A;
return static_cast<TOutput>(std::sin(z) / z);
}

private:
/** Equal to \f$ \frac{\pi}{m} \f$ */
static const double m_Factor;
} // namespace itk
};

/**
Expand All @@ -136,17 +129,16 @@ class ITK_TEMPLATE_EXPORT BlackmanWindowFunction
inline TOutput
operator()(const TInput & A) const
{
return static_cast<TOutput>(0.42 + 0.5 * std::cos(A * m_Factor1) + 0.08 * std::cos(A * m_Factor2));
}
/** Equal to \f$ \frac{\pi}{m} \f$ */
static constexpr double factor1 = Math::pi / VRadius;

private:
/** Equal to \f$ \frac{\pi}{m} \f$ */
static const double m_Factor1;

/** Equal to \f$ \frac{2 \pi}{m} \f$ */
static const double m_Factor2;
/** Equal to \f$ \frac{2 \pi}{m} \f$ */
static constexpr double factor2 = 2.0 * Math::pi / VRadius;
return static_cast<TOutput>(0.42 + 0.5 * std::cos(A * factor1) + 0.08 * std::cos(A * factor2));
}
};
} // namespace Function
// clang-format on

/**
* \class WindowedSincInterpolateImageFunction
Expand Down Expand Up @@ -353,11 +345,10 @@ class ITK_TEMPLATE_EXPORT WindowedSincInterpolateImageFunction
unsigned int m_WeightOffsetTable[m_OffsetTableSize][ImageDimension]{};

/** The sinc function */
inline double
Sinc(double x) const
static double
Sinc(const double x)
{
const double px = itk::Math::pi * x;

const double px = Math::pi * x;
return (x == 0.0) ? 1.0 : std::sin(px) / px;
}
};
Expand Down
23 changes: 0 additions & 23 deletions Modules/Core/ImageFunction/include/itkWindowedSincInterpolateImageFunction.hxx
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Original file line number Diff line number Diff line change
Expand Up @@ -23,29 +23,6 @@

namespace itk
{

// Constant definitions for functions
namespace Function
{
template <unsigned int VRadius, typename TInput, typename TOutput>
const double CosineWindowFunction<VRadius, TInput, TOutput>::m_Factor = itk::Math::pi / (2 * VRadius);

template <unsigned int VRadius, typename TInput, typename TOutput>
const double HammingWindowFunction<VRadius, TInput, TOutput>::m_Factor = itk::Math::pi / VRadius;

template <unsigned int VRadius, typename TInput, typename TOutput>
const double WelchWindowFunction<VRadius, TInput, TOutput>::m_Factor = 1.0 / (VRadius * VRadius);

template <unsigned int VRadius, typename TInput, typename TOutput>
const double LanczosWindowFunction<VRadius, TInput, TOutput>::m_Factor = itk::Math::pi / VRadius;

template <unsigned int VRadius, typename TInput, typename TOutput>
const double BlackmanWindowFunction<VRadius, TInput, TOutput>::m_Factor1 = itk::Math::pi / VRadius;

template <unsigned int VRadius, typename TInput, typename TOutput>
const double BlackmanWindowFunction<VRadius, TInput, TOutput>::m_Factor2 = 2.0 * itk::Math::pi / VRadius;
} // end namespace Function

template <typename TInputImage,
unsigned int VRadius,
typename TWindowFunction,
Expand Down
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