gplan.c File Reference

Routines to chew through tables of perturbations. More...

#include <math.h>
#include <stdlib.h>
#include "aephem.h"

Macros
#define	ae_gplan_mods3600(x)   ((x) - 1.296e6 * floor ((x)/1.296e6))
	A modulo macro.
#define	AE_GPLAN_N_HARMONIC   9
	The length of ae_gplan_freq and ae_gplan_phase.

Functions
void	ae_gplan_sscc (int k, double arg, int n)
	Prepare lookup table of sin and cos (i * Lj) for required multiple angles. More...
void	ae_gplan (double jd_tt, struct ae_plantbl_t *plan, double pobj[])
	Use a table to find a planet's polar, heliocentric position. More...
void	ae_gplan_mean_element (double jd_tt, double *arg)
	Compute mean elements. More...
void	ae_g3plan (double jd_tt, struct ae_plantbl_t *plan, double pobj[], int objnum)
	Accumulate the sum of trigonometric series in three variables. More...
void	ae_g2plan (double jd_tt, struct ae_plantbl_t *plan, double pobj[], double *lp_equinox)
	Accumulate the sum of trigonometric series in two variables. More...
double	ae_g1plan (double jd_tt, struct ae_plantbl_t *plan)
	Accumulate the sum of trigonometric series in one variable. More...
void	ae_gmoon (double jd_tt, double rect[], double pol[])
	Compute geocentric moon position. More...

Variables
double	ae_gplan_freq [AE_GPLAN_N_HARMONIC]
	Orbital frequency harmonics. More...
double	ae_gplan_phase [AE_GPLAN_N_HARMONIC]
	Orbital phase harmonics. More...
double	ae_gplan_ss [AE_PLANTBL_N_HARMONIC][31]
	Sine look-up table for the gplan() routines.
double	ae_gplan_cc [AE_PLANTBL_N_HARMONIC][31]
	Cosine look-up table for the gplan() routines.

Detailed Description

Routines to chew through tables of perturbations.

Function Documentation

double ae_g1plan	(	double	jd_tt,
		struct ae_plantbl_t *	plan
	)

Accumulate the sum of trigonometric series in one variable.

This is a generic routine to accumulate sum of trigonometric series in one variable of the same list of arguments.

Parameters

jd_tt	The Julian date in TT.
plan	A table of planetary orbit data.

Returns

The accumlated sum.

References ae_gplan_cc, ae_gplan_mean_element(), ae_gplan_ss, ae_gplan_sscc(), AE_J2000, AE_PLANTBL_N_HARMONIC, ae_plantbl_t::arg_tbl, ae_plantbl_t::lon_tbl, ae_plantbl_t::max_harmonic, ae_plantbl_t::timescale, and ae_plantbl_t::trunclvl.

Referenced by ae_gmoon().

void ae_g2plan	(	double	jd_tt,
		struct ae_plantbl_t *	plan,
		double	pobj[],
		double *	lp_equinox
	)

Accumulate the sum of trigonometric series in two variables.

This is a generic routine to accumulate sum of trigonometric series in two variables (e.g., longitude, radius) of the same list of arguments.

Parameters

jd_tt	The Julian date in TT.
plan	A table of planetary orbit data.
pobj	For returning the polar position of the planet.
lp_equinox	For returning the lp_equinox (?); set to NULL if it is not not needed

References ae_gplan_cc, ae_gplan_mean_element(), ae_gplan_ss, ae_gplan_sscc(), AE_J2000, AE_PLANTBL_N_HARMONIC, AE_STR, ae_plantbl_t::arg_tbl, ae_plantbl_t::lon_tbl, ae_plantbl_t::max_harmonic, ae_plantbl_t::maxargs, ae_plantbl_t::rad_tbl, ae_plantbl_t::timescale, and ae_plantbl_t::trunclvl.

Referenced by ae_gmoon().

void ae_g3plan	(	double	jd_tt,
		struct ae_plantbl_t *	plan,
		double	pobj[],
		int	objnum
	)

Accumulate the sum of trigonometric series in three variables.

This is a generic program to accumulate sum of trigonometric series in three variables (e.g., longitude, latitude, radius) of the same list of arguments.

Parameters

jd_tt	The Julian date in TT.
plan	A table of planetary orbit data.
pobj	For returning the polar position of the planet.
objnum	The planet number.

References ae_gplan_cc, ae_gplan_mean_element(), ae_gplan_ss, ae_gplan_sscc(), AE_J2000, AE_PLANTBL_N_HARMONIC, AE_STR, ae_plantbl_t::arg_tbl, ae_plantbl_t::distance, ae_plantbl_t::lat_tbl, ae_plantbl_t::lon_tbl, ae_plantbl_t::max_harmonic, ae_plantbl_t::maxargs, ae_plantbl_t::rad_tbl, ae_plantbl_t::timescale, and ae_plantbl_t::trunclvl.

Referenced by ae_kepler().

void ae_gmoon	(	double	jd_tt,
		double	rect[],
		double	pol[]
	)

Compute geocentric moon position.

Parameters

jd_tt	The Julian date in TT.
rect	For returning the position in rectangular coordinates.
pol	For returning the position in polar coordinates.

References ae_epsilon(), ae_g1plan(), ae_g2plan(), ae_mlat404, ae_mlr404, AE_STR, and ae_plantbl_t::distance.

Referenced by ae_geocentric_moon_from_orbit(), and ae_kepler_embofs().

void ae_gplan	(	double	jd_tt,
		struct ae_plantbl_t *	plan,
		double	pobj[]
	)

Use a table to find a planet's polar, heliocentric position.

Parameters

jd_tt	The Julian date in TT.
plan	The planet's orbital table.
pobj	For returning the polar position of the planet.

References ae_gplan_cc, ae_gplan_freq, ae_gplan_mods3600, AE_GPLAN_N_HARMONIC, ae_gplan_phase, ae_gplan_ss, ae_gplan_sscc(), AE_J2000, AE_STR, ae_plantbl_t::arg_tbl, ae_plantbl_t::distance, ae_plantbl_t::lat_tbl, ae_plantbl_t::lon_tbl, ae_plantbl_t::max_harmonic, ae_plantbl_t::maxargs, ae_plantbl_t::rad_tbl, and ae_plantbl_t::timescale.

Referenced by ae_kepler().

void ae_gplan_mean_element	(	double	jd_tt,
		double *	arg
	)

Compute mean elements.

The first nine arguments are for mean longitudes of planets (Simon et al, 1994), with 0.047" subtracted from constant term for offset to DE403 origin.

Parameters

jd_tt	The Julian date in TT.
arg	The mean element arguments.

References ae_gplan_mods3600, and AE_STR.

Referenced by ae_g1plan(), ae_g2plan(), and ae_g3plan().

void ae_gplan_sscc	(	int	k,
		double	arg,
		int	n
	)

Prepare lookup table of sin and cos (i * Lj) for required multiple angles.

Parameters

k	The first index.
arg	The sin/cos argument.
n	The second index.

References ae_gplan_cc, and ae_gplan_ss.

Referenced by ae_g1plan(), ae_g2plan(), ae_g3plan(), and ae_gplan().

Variable Documentation

double ae_gplan_freq[AE_GPLAN_N_HARMONIC]

Initial value:

= {
  53810162868.8982,
  21066413643.3548,
  12959774228.3429,
  6890507749.3988,
  1092566037.7991,
  439960985.5372,
  154248119.3933,
  78655032.0744,
  52272245.1795
}

Orbital frequency harmonics.

Units are seconds of arc per 10000 Julian years. From Simon et al. (1994).

Referenced by ae_gplan().

double ae_gplan_phase[AE_GPLAN_N_HARMONIC]

Initial value:

= {
  252.25090552 * 3600.,
  181.97980085 * 3600.,
  100.46645683 * 3600.,
  355.43299958 * 3600.,
  34.35151874 * 3600.,
  50.07744430 * 3600.,
  314.05500511 * 3600.,
  304.34866548 * 3600.,
  860492.1546
}

Orbital phase harmonics.

Units are seconds of arc. From Simon et al. (1994).

Referenced by ae_gplan().