1 /*
2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software posted to USENET.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 /*
33 * Phase of the Moon. Calculates the current phase of the moon.
34 * Based on routines from `Practical Astronomy with Your Calculator',
35 * by Duffett-Smith. Comments give the section from the book that
36 * particular piece of code was adapted from.
37 *
38 * -- Keith E. Brandt VIII 1984
39 *
40 */
41
42 #include <sys/capsicum.h>
43 #include <capsicum_helpers.h>
44
45 #include <err.h>
46 #include <errno.h>
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <math.h>
50 #include <string.h>
51 #include <sysexits.h>
52 #include <time.h>
53 #include <unistd.h>
54
55 #ifndef PI
56 #define PI 3.14159265358979323846
57 #endif
58 #define EPOCH 85
59 #define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */
60 #define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */
61 #define ECCEN 0.01671542 /* solar orbit eccentricity */
62 #define lzero 18.251907 /* lunar mean long at EPOCH */
63 #define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */
64 #define Nzero 55.204723 /* lunar mean long of node at EPOCH */
65 #define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
66
67 static void adj360(double *);
68 static double dtor(double);
69 static double potm(double);
70 static void usage(char *progname);
71
72 int
main(int argc,char ** argv)73 main(int argc, char **argv)
74 {
75 time_t tt;
76 struct tm GMT, tmd;
77 double days, today, tomorrow;
78 int ch, cnt, pflag = 0;
79 char *odate = NULL, *otime = NULL;
80 char *progname = argv[0];
81
82 if (caph_limit_stdio() < 0)
83 err(1, "unable to limit capabitilities for stdio");
84
85 caph_cache_catpages();
86 if (caph_enter() < 0)
87 err(1, "unable to enter capability mode");
88
89 while ((ch = getopt(argc, argv, "d:pt:")) != -1)
90 switch (ch) {
91 case 'd':
92 odate = optarg;
93 break;
94 case 'p':
95 pflag = 1;
96 break;
97 case 't':
98 otime = optarg;
99 break;
100 default:
101 usage(progname);
102 }
103
104 argc -= optind;
105 argv += optind;
106
107 if (argc)
108 usage(progname);
109
110 /* Adjust based on users preferences */
111 time(&tt);
112 if (otime != NULL || odate != NULL) {
113 /* Save today in case -d isn't specified */
114 localtime_r(&tt, &tmd);
115
116 if (odate != NULL) {
117 tmd.tm_year = strtol(odate, NULL, 10) - 1900;
118 tmd.tm_mon = strtol(odate + 5, NULL, 10) - 1;
119 tmd.tm_mday = strtol(odate + 8, NULL, 10);
120 /* Use midnight as the middle of the night */
121 tmd.tm_hour = 0;
122 tmd.tm_min = 0;
123 tmd.tm_sec = 0;
124 tmd.tm_isdst = -1;
125 }
126 if (otime != NULL) {
127 tmd.tm_hour = strtol(otime, NULL, 10);
128 tmd.tm_min = strtol(otime + 3, NULL, 10);
129 tmd.tm_sec = strtol(otime + 6, NULL, 10);
130 tmd.tm_isdst = -1;
131 }
132 tt = mktime(&tmd);
133 }
134
135 gmtime_r(&tt, &GMT);
136 days = (GMT.tm_yday + 1) + ((GMT.tm_hour +
137 (GMT.tm_min / 60.0) + (GMT.tm_sec / 3600.0)) / 24.0);
138 for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt)
139 days += isleap(1900 + cnt) ? 366 : 365;
140 today = potm(days);
141 if (pflag) {
142 (void)printf("%1.0f\n", today);
143 return (0);
144 }
145 (void)printf("The Moon is ");
146 if (today >= 99.5)
147 (void)printf("Full\n");
148 else if (today < 0.5)
149 (void)printf("New\n");
150 else {
151 tomorrow = potm(days + 1);
152 if (today >= 49.5 && today < 50.5)
153 (void)printf("%s\n", tomorrow > today ?
154 "at the First Quarter" : "at the Last Quarter");
155 else {
156 (void)printf("%s ", tomorrow > today ?
157 "Waxing" : "Waning");
158 if (today > 50)
159 (void)printf("Gibbous (%1.0f%% of Full)\n",
160 today);
161 else if (today < 50)
162 (void)printf("Crescent (%1.0f%% of Full)\n",
163 today);
164 }
165 }
166
167 return 0;
168 }
169
170 /*
171 * potm --
172 * return phase of the moon
173 */
174 static double
potm(double days)175 potm(double days)
176 {
177 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime;
178 double A4, lprime, V, ldprime, D, Nm;
179
180 N = 360 * days / 365.2422; /* sec 42 #3 */
181 adj360(&N);
182 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */
183 adj360(&Msol);
184 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */
185 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */
186 adj360(&LambdaSol);
187 l = 13.1763966 * days + lzero; /* sec 61 #4 */
188 adj360(&l);
189 Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */
190 adj360(&Mm);
191 Nm = Nzero - (0.0529539 * days); /* sec 61 #6 */
192 adj360(&Nm);
193 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */
194 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */
195 A3 = 0.37 * sin(dtor(Msol));
196 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */
197 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */
198 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */
199 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */
200 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */
201 ldprime = lprime + V; /* sec 61 #14 */
202 D = ldprime - LambdaSol; /* sec 63 #2 */
203 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */
204 }
205
206 /*
207 * dtor --
208 * convert degrees to radians
209 */
210 static double
dtor(double deg)211 dtor(double deg)
212 {
213
214 return(deg * PI / 180);
215 }
216
217 /*
218 * adj360 --
219 * adjust value so 0 <= deg <= 360
220 */
221 static void
adj360(double * deg)222 adj360(double *deg)
223 {
224
225 for (;;)
226 if (*deg < 0)
227 *deg += 360;
228 else if (*deg > 360)
229 *deg -= 360;
230 else
231 break;
232 }
233
234 static void
usage(char * progname)235 usage(char *progname)
236 {
237
238 fprintf(stderr, "Usage: %s [-p] [-d yyyy.mm.dd] [-t hh:mm:ss]\n",
239 progname);
240 exit(EX_USAGE);
241 }
242