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https://github.com/mpusz/mp-units.git
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measurement example updated with a starship operator
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@@ -26,95 +26,105 @@
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namespace {
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// root sum of squares
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template<typename T>
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T rss(const T& v1, const T& v2)
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// root sum of squares
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template<typename T>
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T rss(const T& v1, const T& v2)
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{
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return std::sqrt(std::pow(v1, 2) + std::pow(v2, 2));
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}
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template<class T>
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class measurement {
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public:
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using value_type = T;
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measurement() = default;
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constexpr /* explicit */ measurement(const value_type& val, const value_type& err = {}) :
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// cannot be explicit as `magma` concept requires implicit conversions :-(
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value_(val),
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uncertainty_(std::abs(err))
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{
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return std::sqrt(std::pow(v1, 2) + std::pow(v2, 2));
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}
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template<class T>
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class measurement {
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public:
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using value_type = T;
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constexpr const value_type& value() const { return value_; }
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constexpr const value_type& uncertainty() const { return uncertainty_; }
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measurement() = default;
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constexpr value_type relative_uncertainty() const { return uncertainty() / value(); }
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constexpr value_type lower_bound() const { return value() - uncertainty(); }
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constexpr value_type upper_bound() const { return value() + uncertainty(); }
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constexpr /* explicit */ measurement(const value_type& val, const value_type& err = {}): // cannot be explicit as `magma` concept requires implicit conversions :-(
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value_(val), uncertainty_(std::abs(err))
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{
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}
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[[nodiscard]] constexpr measurement operator-() const { return measurement(-value(), uncertainty()); }
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constexpr const value_type& value() const { return value_; }
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constexpr const value_type& uncertainty() const { return uncertainty_; }
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[[nodiscard]] friend constexpr measurement operator+(const measurement& lhs, const measurement& rhs)
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{
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return measurement(lhs.value() + rhs.value(), rss(lhs.uncertainty(), rhs.uncertainty()));
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}
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constexpr value_type relative_uncertainty() const { return uncertainty() / value(); }
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constexpr value_type lower_bound() const { return value() - uncertainty(); }
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constexpr value_type upper_bound() const { return value() + uncertainty(); }
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[[nodiscard]] friend constexpr measurement operator-(const measurement& lhs, const measurement& rhs)
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{
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return measurement(lhs.value() - rhs.value(), rss(lhs.uncertainty(), rhs.uncertainty()));
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}
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[[nodiscard]] constexpr measurement operator-() const { return measurement(-value(), uncertainty()); }
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[[nodiscard]] friend constexpr measurement operator*(const measurement& lhs, const measurement& rhs)
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{
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const auto val = lhs.value() * rhs.value();
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return measurement(val, val * rss(lhs.relative_uncertainty(), rhs.relative_uncertainty()));
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}
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[[nodiscard]] friend constexpr measurement operator+(const measurement& lhs, const measurement& rhs)
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{
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return measurement(lhs.value() + rhs.value(), rss(lhs.uncertainty(), rhs.uncertainty()));
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}
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[[nodiscard]] friend constexpr measurement operator/(const measurement& lhs, const measurement& rhs)
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{
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const auto val = lhs.value() / rhs.value();
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return measurement(val, val * rss(lhs.relative_uncertainty(), rhs.relative_uncertainty()));
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}
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[[nodiscard]] friend constexpr measurement operator-(const measurement& lhs, const measurement& rhs)
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{
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return measurement(lhs.value() - rhs.value(), rss(lhs.uncertainty(), rhs.uncertainty()));
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}
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#if __GNUC__ >= 10
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[[nodiscard]] friend constexpr measurement operator*(const measurement& lhs, const measurement& rhs)
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{
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const auto val = lhs.value() * rhs.value();
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return measurement(val, val * rss(lhs.relative_uncertainty(), rhs.relative_uncertainty()));
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}
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[[nodiscard]] friend constexpr auto operator<=>(const measurement& lhs, const measurement& rhs) = default;
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[[nodiscard]] friend constexpr bool operator==(const measurement& lhs, const measurement& rhs) = default;
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[[nodiscard]] friend constexpr measurement operator/(const measurement& lhs, const measurement& rhs)
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{
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const auto val = lhs.value() / rhs.value();
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return measurement(val, val * rss(lhs.relative_uncertainty(), rhs.relative_uncertainty()));
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}
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#else
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[[nodiscard]] friend constexpr bool operator==(const measurement& lhs, const measurement& rhs)
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{
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return lhs.value() == rhs.value() && lhs.uncertainty() == rhs.uncertainty();
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}
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[[nodiscard]] friend constexpr bool operator==(const measurement& lhs, const measurement& rhs)
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{
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return lhs.value() == rhs.value() && lhs.uncertainty() == rhs.uncertainty();
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}
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[[nodiscard]] friend constexpr bool operator!=(const measurement& lhs, const measurement& rhs)
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{
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return !(lhs == rhs);
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}
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[[nodiscard]] friend constexpr bool operator!=(const measurement& lhs, const measurement& rhs)
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{
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return !(lhs == rhs);
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}
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[[nodiscard]] friend constexpr bool operator<(const measurement& lhs, const measurement& rhs)
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{
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return lhs.value() == rhs.value() ? lhs.uncertainty() < rhs.uncertainty() : lhs.value() < rhs.value();
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}
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[[nodiscard]] friend constexpr bool operator<(const measurement& lhs, const measurement& rhs)
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{
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return lhs.value() == rhs.value() ? lhs.uncertainty() < rhs.uncertainty() : lhs.value() < rhs.value();
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}
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[[nodiscard]] friend constexpr bool operator>(const measurement& lhs, const measurement& rhs)
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{
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return rhs < lhs;
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}
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[[nodiscard]] friend constexpr bool operator>(const measurement& lhs, const measurement& rhs) { return rhs < lhs; }
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[[nodiscard]] friend constexpr bool operator<=(const measurement& lhs, const measurement& rhs)
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{
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return !(rhs < lhs);
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}
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[[nodiscard]] friend constexpr bool operator<=(const measurement& lhs, const measurement& rhs)
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{
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return !(rhs < lhs);
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}
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[[nodiscard]] friend constexpr bool operator>=(const measurement& lhs, const measurement& rhs)
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{
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return !(lhs < rhs);
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}
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[[nodiscard]] friend constexpr bool operator>=(const measurement& lhs, const measurement& rhs)
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{
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return !(lhs < rhs);
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}
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friend std::ostream& operator<<(std::ostream& os, const measurement& v)
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{
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return os << v.value() << " ± " << v.uncertainty();
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}
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#endif
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private:
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value_type value_{};
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value_type uncertainty_{};
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};
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friend std::ostream& operator<<(std::ostream& os, const measurement& v)
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{
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return os << v.value() << " ± " << v.uncertainty();
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}
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private:
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value_type value_{};
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value_type uncertainty_{};
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};
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static_assert(units::Scalar<measurement<double>>);
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} // namespace
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@@ -137,17 +147,15 @@ void example()
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std::cout << "10 * " << length << " = " << 10 * length << '\n';
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}
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} // namespace
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} // namespace
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int main()
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{
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try {
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example();
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}
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catch (const std::exception& ex) {
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} catch (const std::exception& ex) {
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std::cerr << "Unhandled std exception caught: " << ex.what() << '\n';
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}
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catch (...) {
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} catch (...) {
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std::cerr << "Unhandled unknown exception caught\n";
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}
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}
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