pom.c revision 201627
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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36#if 0 37#ifndef lint 38static const char copyright[] = 39"@(#) Copyright (c) 1989, 1993\n\ 40 The Regents of the University of California. All rights reserved.\n"; 41#endif /* not lint */ 42 43#ifndef lint 44static const char sccsid[] = "@(#)pom.c 8.1 (Berkeley) 5/31/93"; 45#endif /* not lint */ 46#endif 47#include <sys/cdefs.h> 48__FBSDID("$FreeBSD: head/games/pom/pom.c 201627 2010-01-06 00:20:37Z delphij $"); 49 50/* 51 * Phase of the Moon. Calculates the current phase of the moon. 52 * Based on routines from `Practical Astronomy with Your Calculator', 53 * by Duffett-Smith. Comments give the section from the book that 54 * particular piece of code was adapted from. 55 * 56 * -- Keith E. Brandt VIII 1984 57 * 58 */ 59 60#include <stdio.h> 61#include <stdlib.h> 62#include <math.h> 63#include <string.h> 64#include <sysexits.h> 65#include <time.h> 66#include <unistd.h> 67 68#ifndef PI 69#define PI 3.14159265358979323846 70#endif 71#define EPOCH 85 72#define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */ 73#define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */ 74#define ECCEN 0.01671542 /* solar orbit eccentricity */ 75#define lzero 18.251907 /* lunar mean long at EPOCH */ 76#define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */ 77#define Nzero 55.204723 /* lunar mean long of node at EPOCH */ 78#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) 79 80static void adj360(double *); 81static double dtor(double); 82static double potm(double); 83static void usage(char *progname); 84 85int 86main(int argc, char **argv) 87{ 88 time_t tt; 89 struct tm GMT, tmd; 90 double days, today, tomorrow; 91 int ch, cnt; 92 char *odate = NULL, *otime = NULL; 93 94 while ((ch = getopt(argc, argv, "d:t:")) != -1) 95 switch (ch) { 96 case 'd': 97 odate = optarg; 98 break; 99 case 't': 100 otime = optarg; 101 break; 102 default: 103 usage(argv[0]); 104 } 105 106 argc -= optind; 107 argv += optind; 108 109 if (argc) 110 usage(argv[0]); 111 112 /* Adjust based on users preferences */ 113 time(&tt); 114 if (otime != NULL || odate != NULL) { 115 /* Save today in case -d isn't specified */ 116 localtime_r(&tt, &tmd); 117 118 if (odate != NULL) { 119 tmd.tm_year = strtol(odate, NULL, 10) - 1900; 120 tmd.tm_mon = strtol(odate + 5, NULL, 10) - 1; 121 tmd.tm_mday = strtol(odate + 8, NULL, 10); 122 /* Use midnight as the middle of the night */ 123 tmd.tm_hour = 0; 124 tmd.tm_min = 0; 125 tmd.tm_sec = 0; 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 } 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) + .5; 141 (void)printf("The Moon is "); 142 if ((int)today == 100) 143 (void)printf("Full\n"); 144 else if (!(int)today) 145 (void)printf("New\n"); 146 else { 147 tomorrow = potm(days + 1); 148 if ((int)today == 50) 149 (void)printf("%s\n", tomorrow > today ? 150 "at the First Quarter" : "at the Last Quarter"); 151 else { 152 (void)printf("%s ", tomorrow > today ? 153 "Waxing" : "Waning"); 154 if (today > 50) 155 (void)printf("Gibbous (%1.0f%% of Full)\n", 156 today); 157 else if (today < 50) 158 (void)printf("Crescent (%1.0f%% of Full)\n", 159 today); 160 } 161 } 162 163 return 0; 164} 165 166/* 167 * potm -- 168 * return phase of the moon 169 */ 170static double 171potm(double days) 172{ 173 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; 174 double A4, lprime, V, ldprime, D, Nm; 175 176 N = 360 * days / 365.2422; /* sec 42 #3 */ 177 adj360(&N); 178 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */ 179 adj360(&Msol); 180 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */ 181 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */ 182 adj360(&LambdaSol); 183 l = 13.1763966 * days + lzero; /* sec 61 #4 */ 184 adj360(&l); 185 Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */ 186 adj360(&Mm); 187 Nm = Nzero - (0.0529539 * days); /* sec 61 #6 */ 188 adj360(&Nm); 189 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */ 190 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */ 191 A3 = 0.37 * sin(dtor(Msol)); 192 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */ 193 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */ 194 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */ 195 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */ 196 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */ 197 ldprime = lprime + V; /* sec 61 #14 */ 198 D = ldprime - LambdaSol; /* sec 63 #2 */ 199 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */ 200} 201 202/* 203 * dtor -- 204 * convert degrees to radians 205 */ 206static double 207dtor(double deg) 208{ 209 210 return(deg * PI / 180); 211} 212 213/* 214 * adj360 -- 215 * adjust value so 0 <= deg <= 360 216 */ 217static void 218adj360(double *deg) 219{ 220 221 for (;;) 222 if (*deg < 0) 223 *deg += 360; 224 else if (*deg > 360) 225 *deg -= 360; 226 else 227 break; 228} 229 230static void 231usage(char *progname) 232{ 233 234 fprintf(stderr, "Usage: %s [-d yyyy.mm.dd] [-t hh:mm:ss]\n", progname); 235 exit(EX_USAGE); 236} 237