bessel_kn.hpp

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#pragma once
 
#include <cmath>
 
#if defined(__cpp_lib_math_special_functions) || !defined(NUMCPP_NO_USE_BOOST)
 
#include "NumCpp/Core/Internal/StaticAsserts.hpp"
#include "NumCpp/Core/Internal/StlAlgorithms.hpp"
#include "NumCpp/NdArray.hpp"
 
#ifndef __cpp_lib_math_special_functions
#include "boost/math/special_functions/bessel.hpp"
#endif
 
#include <type_traits>
 
namespace nc::special
{
    //============================================================================
    // Method Description:
    template<typename dtype1, typename dtype2>
    auto bessel_kn(dtype1 inV, dtype2 inX)
    {
        STATIC_ASSERT_ARITHMETIC(dtype1);
        STATIC_ASSERT_ARITHMETIC(dtype2);
 
#ifdef __cpp_lib_math_special_functions
        return std::cyl_bessel_k(static_cast<double>(inV), static_cast<double>(inX));
#else
        return boost::math::cyl_bessel_k(static_cast<double>(inV), static_cast<double>(inX));
#endif
    }
 
    //============================================================================
    // Method Description:
    template<typename dtype1, typename dtype2>
    auto bessel_kn(dtype1 inV, const NdArray<dtype2>& inArrayX)
    {
        NdArray<decltype(bessel_kn(dtype1{ 0 }, dtype2{ 0 }))> returnArray(inArrayX.shape());
 
        stl_algorithms::transform(inArrayX.cbegin(),
                                  inArrayX.cend(),
                                  returnArray.begin(),
                                  [inV](dtype2 inX) -> auto { return bessel_kn(inV, inX); });
 
        return returnArray;
    }
} // namespace nc::special
 
#endif // #if defined(__cpp_lib_math_special_functions) || !defined(NUMCPP_NO_USE_BOOST)