libnova  v 0.16.0

Examples of how to use solar functions.

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
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 <>
A simple example showing some solar calculations.
#include <stdio.h>
#include <libnova/solar.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_equ_posn equ;
struct ln_rst_time rst;
struct ln_zonedate rise, set, transit;
struct ln_lnlat_posn observer;
struct ln_helio_posn pos;
double JD;
/* observers location (Edinburgh), used to calc rst */ = 55.92; /* 55.92 N */
observer.lng = -3.18; /* 3.18 W */
/* get Julian day from local time */
fprintf(stdout, "JD %f\n", JD);
/* geometric coordinates */
fprintf(stdout, "Solar Coords longitude (deg) %f\n", pos.L);
fprintf(stdout, " latitude (deg) %f\n", pos.B);
fprintf(stdout, " radius vector (AU) %f\n", pos.R);
/* ra, dec */
fprintf(stdout, "Solar Position RA %f\n", equ.ra);
fprintf(stdout, " DEC %f\n", equ.dec);
/* rise, set and transit */
if (ln_get_solar_rst(JD, &observer, &rst) != 0)
fprintf(stdout, "Sun 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;