mars.c

Examples of how to use planetary 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
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 planetary calculations.

*/

#include <stdio.h>
#include <libnova/mars.h>
#include <libnova/julian_day.h>
#include <libnova/rise_set.h>
#include <libnova/transform.h>
#include <libnova/utility.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_helio_posn pos;
        struct lnh_equ_posn hequ;
        struct ln_equ_posn equ;
        struct ln_rst_time rst;
        struct ln_zonedate rise, set, transit;
        struct ln_lnlat_posn observer;
        double JD;
        double au;
        
        /* observers location (Edinburgh), used to calc rst */
        observer.lat = 55.92; /* 55.92 N */
        observer.lng = -3.18; /* 3.18 W */
        
        /* get Julian day from local time */
        JD = ln_get_julian_from_sys();  
        fprintf(stdout, "JD %f\n", JD);
        
        /* longitude, latitude and radius vector */
        ln_get_mars_helio_coords(JD, &pos);     
        fprintf(stdout, "Mars L %f B %f R %f\n", pos.L, pos.B, pos.R);
        
        /* RA, DEC */
        ln_get_mars_equ_coords(JD, &equ);
        ln_equ_to_hequ(&equ, &hequ);
        fprintf(stdout, "Mars RA %d:%d:%f Dec %d:%d:%f\n",
                hequ.ra.hours, hequ.ra.minutes, hequ.ra.seconds,
                hequ.dec.degrees, hequ.dec.minutes, hequ.dec.seconds);
        
        /* Earth - Mars dist AU */
        au = ln_get_mars_earth_dist(JD);
        fprintf(stdout, "mars -> Earth dist (AU) %f\n",au);
        
        /* Sun - Mars Dist AU */
        au = ln_get_mars_solar_dist(JD);
        fprintf(stdout, "mars -> Sun dist (AU) %f\n",au);
        
        /* Mars disk, magnitude and phase */
        au = ln_get_mars_disk(JD);
        fprintf(stdout, "mars -> illuminated disk %f\n",au);
        au = ln_get_mars_magnitude(JD);
        fprintf(stdout, "mars -> magnitude %f\n",au);
        au = ln_get_mars_phase(JD);
        fprintf(stdout, "mars -> phase %f\n",au);
        
                /* rise, set and transit time */
        if (ln_get_mars_rst(JD, &observer, &rst) != 0)
                fprintf(stdout, "Mars 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;
}