spacing.hpp

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#pragma once
 
#include <sycl/sycl.hpp>
 
namespace dpnp::kernels::spacing
{
template <typename argT, typename resT>
struct SpacingFunctor
{
    // is function constant for given argT
    using is_constant = typename std::false_type;
    // constant value, if constant
    // constexpr resT constant_value = resT{};
    // is function defined for sycl::vec
    using supports_vec = typename std::false_type;
    // do both argT and resT support subgroup store/load operation
    using supports_sg_loadstore = typename std::true_type;
 
    resT operator()(const argT &x) const
    {
        if (sycl::isnan(x)) {
            return x;
        }
 
        if (sycl::isinf(x)) {
            return std::numeric_limits<resT>::quiet_NaN();
        }
 
        constexpr argT inf = std::numeric_limits<argT>::infinity();
        if constexpr (std::is_same_v<argT, sycl::half>) {
            // numpy always computes spacing towards +inf for float16 dtype
            return sycl::nextafter(x, inf) - x;
        }
        else {
            return sycl::nextafter(x, sycl::copysign(inf, x)) - x;
        }
    }
};
} // namespace dpnp::kernels::spacing