astro::delta_t::algo1 Namespace Reference

Classes
struct	Algo1Coefficients
	The coefficients of algorithm 1. More...

Functions
constexpr auto	find_coefficients (const int32_t year) -> std::optional< std::pair< Algo1Coefficients, Algo1Coefficients > >
	Get the coefficients of algorithm 1. Returns std::nullopt if not found.
constexpr auto	compute (const double year) -> double
	Compute ΔT for a decimal Gregorian year using algorithm 1.

Variables
constexpr double	MINIMUM_YEAR
constexpr std::array< Algo1Coefficients, 20 >	ALGO1_COEFFICIENTS

Function Documentation

compute()

auto astro::delta_t::algo1::compute ( const double year ) ->double

nodiscardconstexpr

Compute ΔT for a decimal Gregorian year using algorithm 1.

Parameters

year	The year, of double type.

Returns

ΔT in seconds.

Exceptions

std::invalid_argument

if the year is < -4000 or not finite.

Example

compute(2005.99999999....) returns ΔT for the last moment of year 2005.

Example

compute(1984.0) returns ΔT for the first moment of year 1984.

See also

Xu Jianwei, 寿星万年历2008版(V1.3.2) - https://web.archive.org/web/20080919020456id_/http://www.fjptsz.com/xxjs/xjw/rj/115.htm

Note

The original algorithm takes integers as input. But I am using doubles here, with the hope of getting more accurate results.

Frozen comparison model.

find_coefficients()

auto astro::delta_t::algo1::find_coefficients ( const int32_t year ) ->std::optional< std::pair< Algo1Coefficients, Algo1Coefficients > >

constexpr

Get the coefficients of algorithm 1. Returns std::nullopt if not found.

Variable Documentation

ALGO1_COEFFICIENTS

std::array<Algo1Coefficients, 20> astro::delta_t::algo1::ALGO1_COEFFICIENTS

inlineconstexpr

MINIMUM_YEAR

double astro::delta_t::algo1::MINIMUM_YEAR

inlineconstexpr