/* 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 <liam@gnova.org> A simple example showing some comet calculations. Comet Enckle */ #include <stdio.h> #include <libnova/comet.h> #include <libnova/julian_day.h> #include <libnova/rise_set.h> #include <libnova/transform.h> #include <libnova/elliptic_motion.h> void print_date (char * title, struct ln_zonedate* date) { printf ("\n%s\n",title); printf (" Year : %d\n", date->years); printf (" Month : %d\n", date->months); printf (" Day : %d\n", date->days); printf (" Hours : %d\n", date->hours); printf (" Minutes : %d\n", date->minutes); printf (" Seconds : %f\n", date->seconds); printf("gmtoff %ld\n", date->gmtoff); } int main (int argc, char * argv[]) { struct ln_equ_posn equ; struct ln_rst_time rst; struct ln_zonedate rise, set, transit; struct ln_date epoch_date; struct ln_lnlat_posn observer; struct ln_ell_orbit orbit; struct ln_rect_posn posn; double JD, e_JD; double E, v, V, r, l, dist; /* 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(); printf ("JD %f\n", JD); /* calc epoch JD */ epoch_date.years = 1990; epoch_date.months = 10; epoch_date.days = 28; epoch_date.hours = 12; epoch_date.minutes = 30; epoch_date.seconds = 0; e_JD = ln_get_julian_day (&epoch_date); /* Enckle orbital elements */ orbit.JD = e_JD; orbit.a = 2.2091404; orbit.e = 0.8502196; orbit.i = 11.94525; orbit.omega = 334.75006; orbit.w = 186.23352; orbit.n = 0; /* solve kepler for orbit */ E = ln_solve_kepler (0.1, 5.0); printf("(Equation of kepler) E when e is 0.1 and M is 5.0 %f\n ", E); /* true anomaly */ v = ln_get_ell_true_anomaly (0.1, E); printf("(True Anomaly) v when e is 0.1 and E is 5.5545 %f\n ", v); /* radius vector */ r = ln_get_ell_radius_vector (0.5, 0.1, E); printf ("(Radius Vector) r when v is , e is 0.1 and E is 5.5545 %f\n ", r); /* geocentric rect coords */ ln_get_ell_geo_rect_posn (&orbit, JD, &posn); printf ("(Geocentric Rect Coords X) for comet Enckle %f\n", posn.X); printf ("(Geocentric Rect Coords Y) for comet Enckle %f\n", posn.Y); printf ("(Geocentric Rect Coords Z) for comet Enckle %f\n", posn.Z); /* rectangular coords */ ln_get_ell_helio_rect_posn (&orbit, JD, &posn); printf ("(Heliocentric Rect Coords X) for comet Enckle %f\n ", posn.X); printf ("(Heliocentric Rect Coords Y) for comet Enckle %f\n ", posn.Y); printf ("(Heliocentric Rect Coords Z) for comet Enckle %f\n ", posn.Z); /* ra, dec */ ln_get_ell_body_equ_coords (JD, &orbit, &equ); printf ("(RA) for comet Enckle %f\n ", equ.ra); printf ("(Dec) for comet Enckle %f\n ", equ.dec); /* orbit length */ l = ln_get_ell_orbit_len (&orbit); printf ("(Orbit Length) for comet Enckle in AU %f\n ", l); /* orbital velocity at perihelion */ V = ln_get_ell_orbit_pvel (&orbit); printf ("(Orbit Perihelion Vel) for comet Enckle in kms %f\n ", V); /* orbital velocity at aphelion */ V = ln_get_ell_orbit_avel (&orbit); printf ("(Orbit Aphelion Vel) for comet Enckle in kms %f\n ", V); /* average orbital velocity */ V = ln_get_ell_orbit_vel (JD, &orbit); printf ("(Orbit Vel JD) for comet Enckle in kms %f\n ", V); /* comet sun distance */ dist = ln_get_ell_body_solar_dist (JD, &orbit); printf ("(Body Solar Dist) for comet Enckle in AU %f\n ", dist); /* comet earth distance */ dist = ln_get_ell_body_earth_dist (JD, &orbit); printf ("(Body Earth Dist) for comet Enckle in AU %f\n ", dist); /* rise, set and transit */ if (ln_get_ell_body_rst (JD, &observer, &orbit, &rst) == 1) printf ("Comet 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; }