compensated_sum.hpp

// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: Copyright 2020-2024 Heal Research
 
#ifndef VSTAT_COMPENSATED_SUM_HPP
#define VSTAT_COMPENSATED_SUM_HPP
 
#include <eve/module/core.hpp>
 
namespace VSTAT_NAMESPACE
{
 
template<typename T>
struct compensated_sum
{
    constexpr void operator()(T x) noexcept
    {
        auto [t, e] = eve::two_add(sum_, x);
        comp_ += e;
        sum_ = t;
    }
 
    [[nodiscard]] constexpr auto value() const noexcept -> T { return sum_ + comp_; }
 
  private:
    T sum_ {0};
    T comp_ {0};
};
 
}  // namespace VSTAT_NAMESPACE
 
#endif