astro::sun::geocentric_coord::math::detail Namespace Reference

Functions
auto	solar_longitude (const double jde) -> double
	Calculate the apparent geocentric longitude of the Sun.
auto	get_start_jde (const int32_t year) -> double
	Return the JDE of the start of the year.
auto	get_end_jde (const int32_t year) -> double
	Return the JDE of the end of the year.
auto	get_start_lon (const int32_t year) -> double
	Return the apparent geocentric longitude of the Sun at the start of the year.
auto	get_end_lon (const int32_t year) -> double
	Return the apparent geocentric longitude of the Sun at the end of the year.
auto	has_root_before_spring_equinox (const int32_t year, const double lon) -> bool
	Return true if the given year has a root for the given lon before the spring equinox.
auto	has_root_after_spring_equinox (const int32_t year, const double lon) -> bool
	Return true if the given year has a root for the given lon after the spring equinox.
auto	make_f (const int32_t year, const double expected_lon)
	Lift solar longitude from the year's start for Newton refinement.

Detailed Description

See also

https://github.com/0xf3cd/celestial-calendar/blob/main/statistics/sun_longitude.ipynb

https://github.com/leetcola/nong/wiki/算法系列之十八：用天文方法计算二十四节气（上）

https://github.com/leetcola/nong/wiki/算法系列之十八：用天文方法计算二十四节气（下）

Function Documentation

get_end_jde()

auto astro::sun::geocentric_coord::math::detail::get_end_jde ( const int32_t year ) ->double

inlinenodiscard

Return the JDE of the end of the year.

Parameters

year	The Gregorian year, in [1, 32766]; see astro::julian_day::validate_annual_year.

get_end_lon()

auto astro::sun::geocentric_coord::math::detail::get_end_lon ( const int32_t year ) ->double

inlinenodiscard

Return the apparent geocentric longitude of the Sun at the end of the year.

get_start_jde()

auto astro::sun::geocentric_coord::math::detail::get_start_jde ( const int32_t year ) ->double

inlinenodiscard

Return the JDE of the start of the year.

Parameters

year	The Gregorian year, in [1, 32767]; see astro::julian_day::utc_year_start_jde.

get_start_lon()

auto astro::sun::geocentric_coord::math::detail::get_start_lon ( const int32_t year ) ->double

inlinenodiscard

Return the apparent geocentric longitude of the Sun at the start of the year.

has_root_after_spring_equinox()

auto astro::sun::geocentric_coord::math::detail::has_root_after_spring_equinox ( const int32_t year, const double lon )->bool

inlinenodiscard

Return true if the given year has a root for the given lon after the spring equinox.

has_root_before_spring_equinox()

auto astro::sun::geocentric_coord::math::detail::has_root_before_spring_equinox ( const int32_t year, const double lon )->bool

inlinenodiscard

Return true if the given year has a root for the given lon before the spring equinox.

make_f()

auto astro::sun::geocentric_coord::math::detail::make_f ( const int32_t year, const double expected_lon )

inlinenodiscard

Lift solar longitude from the year's start for Newton refinement.

Note

The mean-motion predictor must stay within 180 degrees of the continuous lift over the search span.

solar_longitude()

auto astro::sun::geocentric_coord::math::detail::solar_longitude ( const double jde ) ->double

inlinenodiscard

Calculate the apparent geocentric longitude of the Sun.

Parameters

jde	The julian ephemeris day number, which is based on TT.

Returns

The apparent geocentric longitude of the Sun in degrees.

Note

The solver's own view of the Sun: newton_method works on bare doubles, and this is where the typed astronomy layer is handed over to it. Callers after a solar longitude want geocentric_coord::apparent(jde).λ, which keeps the unit in the type (#125).