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 caph_cache_tzdata();
87 if (caph_enter() < 0)
88 err(1, "unable to enter capability mode");
89
90 while ((ch = getopt(argc, argv, "d:pt:")) != -1)
91 switch (ch) {
92 case 'd':
93 odate = optarg;
94 break;
95 case 'p':
96 pflag = 1;
97 break;
98 case 't':
99 otime = optarg;
100 break;
101 default:
102 usage(progname);
103 }
104
105 argc -= optind;
106 argv += optind;
107
108 if (argc)
109 usage(progname);
110
111 /* Adjust based on users preferences */
112 time(&tt);
113 if (otime != NULL || odate != NULL) {
114 /* Save today in case -d isn't specified */
115 localtime_r(&tt, &tmd);
116
117 if (odate != NULL) {
118 tmd.tm_year = strtol(odate, NULL, 10) - 1900;
119 tmd.tm_mon = strtol(odate + 5, NULL, 10) - 1;
120 tmd.tm_mday = strtol(odate + 8, NULL, 10);
121 /* Use midnight as the middle of the night */
122 tmd.tm_hour = 0;
123 tmd.tm_min = 0;
124 tmd.tm_sec = 0;
125 tmd.tm_isdst = -1;
126 }
127 if (otime != NULL) {
128 tmd.tm_hour = strtol(otime, NULL, 10);
129 tmd.tm_min = strtol(otime + 3, NULL, 10);
130 tmd.tm_sec = strtol(otime + 6, NULL, 10);
131 tmd.tm_isdst = -1;
132 }
133 tt = mktime(&tmd);
134 }
135
136 gmtime_r(&tt, &GMT);
137 days = (GMT.tm_yday + 1) + ((GMT.tm_hour +
138 (GMT.tm_min / 60.0) + (GMT.tm_sec / 3600.0)) / 24.0);
139 for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt)
140 days += isleap(1900 + cnt) ? 366 : 365;
141 today = potm(days);
142 if (pflag) {
143 (void)printf("%1.0f\n", today);
144 return (0);
145 }
146 (void)printf("The Moon is ");
147 if (today >= 99.5)
148 (void)printf("Full\n");
149 else if (today < 0.5)
150 (void)printf("New\n");
151 else {
152 tomorrow = potm(days + 1);
153 if (today >= 49.5 && today < 50.5)
154 (void)printf("%s\n", tomorrow > today ?
155 "at the First Quarter" : "at the Last Quarter");
156 else {
157 (void)printf("%s ", tomorrow > today ?
158 "Waxing" : "Waning");
159 if (today > 50)
160 (void)printf("Gibbous (%1.0f%% of Full)\n",
161 today);
162 else if (today < 50)
163 (void)printf("Crescent (%1.0f%% of Full)\n",
164 today);
165 }
166 }
167
168 return 0;
169 }
170
171 /*
172 * potm --
173 * return phase of the moon
174 */
175 static double
potm(double days)176 potm(double days)
177 {
178 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime;
179 double A4, lprime, V, ldprime, D, Nm;
180
181 N = 360 * days / 365.2422; /* sec 42 #3 */
182 adj360(&N);
183 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */
184 adj360(&Msol);
185 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */
186 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */
187 adj360(&LambdaSol);
188 l = 13.1763966 * days + lzero; /* sec 61 #4 */
189 adj360(&l);
190 Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */
191 adj360(&Mm);
192 Nm = Nzero - (0.0529539 * days); /* sec 61 #6 */
193 adj360(&Nm);
194 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */
195 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */
196 A3 = 0.37 * sin(dtor(Msol));
197 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */
198 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */
199 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */
200 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */
201 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */
202 ldprime = lprime + V; /* sec 61 #14 */
203 D = ldprime - LambdaSol; /* sec 63 #2 */
204 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */
205 }
206
207 /*
208 * dtor --
209 * convert degrees to radians
210 */
211 static double
dtor(double deg)212 dtor(double deg)
213 {
214
215 return(deg * PI / 180);
216 }
217
218 /*
219 * adj360 --
220 * adjust value so 0 <= deg <= 360
221 */
222 static void
adj360(double * deg)223 adj360(double *deg)
224 {
225
226 for (;;)
227 if (*deg < 0)
228 *deg += 360;
229 else if (*deg > 360)
230 *deg -= 360;
231 else
232 break;
233 }
234
235 static void
usage(char * progname)236 usage(char *progname)
237 {
238
239 fprintf(stderr, "Usage: %s [-p] [-d yyyy.mm.dd] [-t hh:mm:ss]\n",
240 progname);
241 exit(EX_USAGE);
242 }
243