1 /*
2 This program is free software; you can redistribute it and/or modify
3 it under the terms of the GNU Library General Public License as published by
4 the Free Software Foundation; either version 2 of the License, or
5 (at your option) any later version.
6
7 This program is distributed in the hope that it will be useful,
8 but WITHOUT ANY WARRANTY; without even the implied warranty of
9 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 GNU General Public License for more details.
11
12 You should have received a copy of the GNU General Public License
13 along with this program; if not, write to the Free Software
14 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
15
16 Copyright (C) 2003 Liam Girdwood <liam@gnova.org>
17
18
19 A simple example showing some comet calculations.
20
21 Comet Enckle
22
23 */
24
25 #include <stdio.h>
26 #include <libnova/comet.h>
27 #include <libnova/julian_day.h>
28 #include <libnova/rise_set.h>
29 #include <libnova/transform.h>
30 #include <libnova/elliptic_motion.h>
31
print_date(char * title,struct ln_zonedate * date)32 void print_date (char * title, struct ln_zonedate* date)
33 {
34 printf ("\n%s\n",title);
35 printf (" Year : %d\n", date->years);
36 printf (" Month : %d\n", date->months);
37 printf (" Day : %d\n", date->days);
38 printf (" Hours : %d\n", date->hours);
39 printf (" Minutes : %d\n", date->minutes);
40 printf (" Seconds : %f\n", date->seconds);
41 printf("gmtoff %ld\n", date->gmtoff);
42 }
43
main(int argc,char * argv[])44 int main (int argc, char * argv[])
45 {
46 struct ln_equ_posn equ;
47 struct ln_rst_time rst;
48 struct ln_zonedate rise, set, transit;
49 struct ln_date epoch_date;
50 struct ln_lnlat_posn observer;
51 struct ln_ell_orbit orbit;
52 struct ln_rect_posn posn;
53 double JD, e_JD;
54 double E, v, V, r, l, dist;
55
56 /* observers location (Edinburgh), used to calc rst */
57 observer.lat = 55.92; /* 55.92 N */
58 observer.lng = -3.18; /* 3.18 W */
59
60 /* get Julian day from local time */
61 JD = ln_get_julian_from_sys();
62 printf ("JD %f\n", JD);
63
64 /* calc epoch JD */
65 epoch_date.years = 1990;
66 epoch_date.months = 10;
67 epoch_date.days = 28;
68 epoch_date.hours = 12;
69 epoch_date.minutes = 30;
70 epoch_date.seconds = 0;
71 e_JD = ln_get_julian_day (&epoch_date);
72
73 /* Enckle orbital elements */
74 orbit.JD = e_JD;
75 orbit.a = 2.2091404;
76 orbit.e = 0.8502196;
77 orbit.i = 11.94525;
78 orbit.omega = 334.75006;
79 orbit.w = 186.23352;
80 orbit.n = 0;
81
82 /* solve kepler for orbit */
83 E = ln_solve_kepler (0.1, 5.0);
84 printf("(Equation of kepler) E when e is 0.1 and M is 5.0 %f\n ", E);
85
86 /* true anomaly */
87 v = ln_get_ell_true_anomaly (0.1, E);
88 printf("(True Anomaly) v when e is 0.1 and E is 5.5545 %f\n ", v);
89
90 /* radius vector */
91 r = ln_get_ell_radius_vector (0.5, 0.1, E);
92 printf ("(Radius Vector) r when v is , e is 0.1 and E is 5.5545 %f\n ", r);
93
94 /* geocentric rect coords */
95 ln_get_ell_geo_rect_posn (&orbit, JD, &posn);
96 printf ("(Geocentric Rect Coords X) for comet Enckle %f\n", posn.X);
97 printf ("(Geocentric Rect Coords Y) for comet Enckle %f\n", posn.Y);
98 printf ("(Geocentric Rect Coords Z) for comet Enckle %f\n", posn.Z);
99
100 /* rectangular coords */
101 ln_get_ell_helio_rect_posn (&orbit, JD, &posn);
102 printf ("(Heliocentric Rect Coords X) for comet Enckle %f\n ", posn.X);
103 printf ("(Heliocentric Rect Coords Y) for comet Enckle %f\n ", posn.Y);
104 printf ("(Heliocentric Rect Coords Z) for comet Enckle %f\n ", posn.Z);
105
106 /* ra, dec */
107 ln_get_ell_body_equ_coords (JD, &orbit, &equ);
108 printf ("(RA) for comet Enckle %f\n ", equ.ra);
109 printf ("(Dec) for comet Enckle %f\n ", equ.dec);
110
111 /* orbit length */
112 l = ln_get_ell_orbit_len (&orbit);
113 printf ("(Orbit Length) for comet Enckle in AU %f\n ", l);
114
115 /* orbital velocity at perihelion */
116 V = ln_get_ell_orbit_pvel (&orbit);
117 printf ("(Orbit Perihelion Vel) for comet Enckle in kms %f\n ", V);
118
119 /* orbital velocity at aphelion */
120 V = ln_get_ell_orbit_avel (&orbit);
121 printf ("(Orbit Aphelion Vel) for comet Enckle in kms %f\n ", V);
122
123 /* average orbital velocity */
124 V = ln_get_ell_orbit_vel (JD, &orbit);
125 printf ("(Orbit Vel JD) for comet Enckle in kms %f\n ", V);
126
127 /* comet sun distance */
128 dist = ln_get_ell_body_solar_dist (JD, &orbit);
129 printf ("(Body Solar Dist) for comet Enckle in AU %f\n ", dist);
130
131 /* comet earth distance */
132 dist = ln_get_ell_body_earth_dist (JD, &orbit);
133 printf ("(Body Earth Dist) for comet Enckle in AU %f\n ", dist);
134
135 /* rise, set and transit */
136 if (ln_get_ell_body_rst (JD, &observer, &orbit, &rst) == 1)
137 printf ("Comet is circumpolar\n");
138 else {
139 ln_get_local_date (rst.rise, &rise);
140 ln_get_local_date (rst.transit, &transit);
141 ln_get_local_date (rst.set, &set);
142 print_date ("Rise", &rise);
143 print_date ("Transit", &transit);
144 print_date ("Set", &set);
145 }
146
147 return 0;
148 }
149