File: lunar.c

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/*
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 

Copyright (C) 2003 Liam Girdwood <lgirdwood@gmail.com>


A simple example showing some lunar calculations.

*/

#include <stdio.h>
#include <libnova/lunar.h>
#include <libnova/julian_day.h>
#include <libnova/rise_set.h>
#include <libnova/transform.h>

static void print_date(char *title, struct ln_zonedate *date)
{
	fprintf(stdout, "\n%s\n",title);
	fprintf(stdout, " Year    : %d\n", date->years);
	fprintf(stdout, " Month   : %d\n", date->months);
	fprintf(stdout, " Day     : %d\n", date->days);
	fprintf(stdout, " Hours   : %d\n", date->hours);
	fprintf(stdout, " Minutes : %d\n", date->minutes);
	fprintf(stdout, " Seconds : %f\n", date->seconds);
}

int main(int argc, const char *argv[])
{
	struct ln_rect_posn moon;
	struct ln_equ_posn equ;
	struct ln_lnlat_posn ecl;
	struct ln_lnlat_posn observer;
	struct ln_rst_time rst;
	struct ln_zonedate rise, transit, set;
	double JD;

	/* observers location (Edinburgh), used to calc rst */
	observer.lat = 55.92; /* 55.92 N */
	observer.lng = -3.18; /* 3.18 W */
	
	/* get the julian day from the local system time */
	JD = ln_get_julian_from_sys();
	fprintf(stdout, "JD %f\n",JD);
	
	/* get the lunar geopcentric position in km, earth is at 0,0,0 */
	ln_get_lunar_geo_posn(JD, &moon, 0);
	fprintf(stdout, "lunar x %f  y %f  z %f\n", moon.X, moon.Y, moon.Z);
	
	/* Long Lat */
	ln_get_lunar_ecl_coords(JD, &ecl, 0);
	fprintf(stdout, "lunar long %f  lat %f\n", ecl.lng, ecl.lat);
	
	/* RA, DEC */
	ln_get_lunar_equ_coords(JD, &equ);
	fprintf(stdout, "lunar RA %f  Dec %f\n", equ.ra, equ.dec);
	
	/* moon earth distance */
	fprintf(stdout, "lunar distance km %f\n", ln_get_lunar_earth_dist(JD));
	
	/* lunar disk, phase and bright limb */
	fprintf(stdout, "lunar disk %f\n", ln_get_lunar_disk(JD));
	fprintf(stdout, "lunar phase %f\n", ln_get_lunar_phase(JD));
	fprintf(stdout, "lunar bright limb %f\n", ln_get_lunar_bright_limb(JD));
	
	/* rise, set and transit time */
	if (ln_get_lunar_rst(JD, &observer, &rst) != 0)
		fprintf(stdout, "Moon is circumpolar\n");
	else {
		ln_get_local_date(rst.rise, &rise);
		ln_get_local_date(rst.transit, &transit);
		ln_get_local_date(rst.set, &set);
		print_date("Rise", &rise);
		print_date("Transit", &transit);
		print_date("Set", &set);
	}
	
	/* rise, set and transit time */
	if (ln_get_lunar_rst(JD - 24, &observer, &rst) != 0)
		fprintf(stdout, "Moon is circumpolar\n");
	else {
		ln_get_local_date(rst.rise, &rise);
		ln_get_local_date(rst.transit, &transit);
		ln_get_local_date(rst.set, &set);
		print_date("Rise", &rise);
		print_date("Transit", &transit);
		print_date("Set", &set);
	}
	
	/* rise, set and transit time */
	if (ln_get_lunar_rst(JD - 25, &observer, &rst) != 0)
		fprintf(stdout, "Moon is circumpolar\n");
	else {
		ln_get_local_date(rst.rise, &rise);
		ln_get_local_date(rst.transit, &transit);
		ln_get_local_date(rst.set, &set);
		print_date("Rise", &rise);
		print_date("Transit", &transit);
		print_date("Set", &set);
	}
	
	return 0;
}