legendre_q.hpp

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#pragma once
 
#ifndef NUMCPP_NO_USE_BOOST
 
#include "boost/math/special_functions/legendre.hpp"
 
#include "NumCpp/Core/Internal/StaticAsserts.hpp"
#include "NumCpp/Core/Internal/StlAlgorithms.hpp"
#include "NumCpp/NdArray.hpp"
 
namespace nc::polynomial
{
    //============================================================================
    // Method Description:
    template<typename dtype>
    double legendre_q(int32 n, dtype x)
    {
        STATIC_ASSERT_ARITHMETIC(dtype);
 
        if (x < -1. || x > 1.)
        {
            THROW_INVALID_ARGUMENT_ERROR("input x must be of the range [-1, 1].");
        }
 
        return boost::math::legendre_q(n, static_cast<double>(x));
    }
 
    //============================================================================
    // Method Description:
    template<typename dtype>
    NdArray<double> legendre_q(int32 n, const NdArray<dtype>& inArrayX)
    {
        NdArray<double> returnArray(inArrayX.shape());
 
        const auto function = [n](dtype x) -> double { return legendre_q(n, x); };
 
        stl_algorithms::transform(inArrayX.cbegin(), inArrayX.cend(), returnArray.begin(), function);
 
        return returnArray;
    }
} // namespace nc::polynomial
 
#endif // #ifndef NUMCPP_NO_USE_BOOST