logaddexp2.hpp

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#pragma once
 
#include <cmath>
#include <sycl/sycl.hpp>
 
namespace dpnp::kernels::logaddexp2
{
constexpr double log2e = 1.442695040888963407359924681001892137;
 
template <typename T>
inline T log2_1p(T x)
{
    return T(log2e) * sycl::log1p(x);
}
 
template <typename T>
inline T logaddexp2(T x, T y)
{
    if (x == y) {
        // handles infinities of the same sign
        return x + 1;
    }
 
    const T tmp = x - y;
    if (tmp > 0) {
        return x + log2_1p(sycl::exp2(-tmp));
    }
    else if (tmp <= 0) {
        return y + log2_1p(sycl::exp2(tmp));
    }
    return std::numeric_limits<T>::quiet_NaN();
}
 
template <typename argT1, typename argT2, typename resT>
struct Logaddexp2Functor
{
    using supports_sg_loadstore = std::true_type;
    using supports_vec = std::false_type;
 
    resT operator()(const argT1 &in1, const argT2 &in2) const
    {
        return logaddexp2<resT>(in1, in2);
    }
};
} // namespace dpnp::kernels::logaddexp2