pom.c revision 225736
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#if 0 33#ifndef lint 34static const char copyright[] = 35"@(#) Copyright (c) 1989, 1993\n\ 36 The Regents of the University of California. All rights reserved.\n"; 37#endif /* not lint */ 38 39#ifndef lint 40static const char sccsid[] = "@(#)pom.c 8.1 (Berkeley) 5/31/93"; 41#endif /* not lint */ 42#endif 43#include <sys/cdefs.h> 44__FBSDID("$FreeBSD: stable/9/games/pom/pom.c 210089 2010-07-15 00:16:04Z emaste $"); 45 46/* 47 * Phase of the Moon. Calculates the current phase of the moon. 48 * Based on routines from `Practical Astronomy with Your Calculator', 49 * by Duffett-Smith. Comments give the section from the book that 50 * particular piece of code was adapted from. 51 * 52 * -- Keith E. Brandt VIII 1984 53 * 54 */ 55 56#include <stdio.h> 57#include <stdlib.h> 58#include <math.h> 59#include <string.h> 60#include <sysexits.h> 61#include <time.h> 62#include <unistd.h> 63 64#ifndef PI 65#define PI 3.14159265358979323846 66#endif 67#define EPOCH 85 68#define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */ 69#define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */ 70#define ECCEN 0.01671542 /* solar orbit eccentricity */ 71#define lzero 18.251907 /* lunar mean long at EPOCH */ 72#define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */ 73#define Nzero 55.204723 /* lunar mean long of node at EPOCH */ 74#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) 75 76static void adj360(double *); 77static double dtor(double); 78static double potm(double); 79static void usage(char *progname); 80 81int 82main(int argc, char **argv) 83{ 84 time_t tt; 85 struct tm GMT, tmd; 86 double days, today, tomorrow; 87 int ch, cnt, pflag = 0; 88 char *odate = NULL, *otime = NULL; 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(argv[0]); 103 } 104 105 argc -= optind; 106 argv += optind; 107 108 if (argc) 109 usage(argv[0]); 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 } 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 } 131 tt = mktime(&tmd); 132 } 133 134 gmtime_r(&tt, &GMT); 135 days = (GMT.tm_yday + 1) + ((GMT.tm_hour + 136 (GMT.tm_min / 60.0) + (GMT.tm_sec / 3600.0)) / 24.0); 137 for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt) 138 days += isleap(1900 + cnt) ? 366 : 365; 139 today = potm(days) + .5; 140 if (pflag) { 141 (void)printf("%1.0f\n", today); 142 return (0); 143 } 144 (void)printf("The Moon is "); 145 if ((int)today == 100) 146 (void)printf("Full\n"); 147 else if (!(int)today) 148 (void)printf("New\n"); 149 else { 150 tomorrow = potm(days + 1); 151 if ((int)today == 50) 152 (void)printf("%s\n", tomorrow > today ? 153 "at the First Quarter" : "at the Last Quarter"); 154 else { 155 (void)printf("%s ", tomorrow > today ? 156 "Waxing" : "Waning"); 157 if (today > 50) 158 (void)printf("Gibbous (%1.0f%% of Full)\n", 159 today); 160 else if (today < 50) 161 (void)printf("Crescent (%1.0f%% of Full)\n", 162 today); 163 } 164 } 165 166 return 0; 167} 168 169/* 170 * potm -- 171 * return phase of the moon 172 */ 173static double 174potm(double days) 175{ 176 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; 177 double A4, lprime, V, ldprime, D, Nm; 178 179 N = 360 * days / 365.2422; /* sec 42 #3 */ 180 adj360(&N); 181 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */ 182 adj360(&Msol); 183 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */ 184 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */ 185 adj360(&LambdaSol); 186 l = 13.1763966 * days + lzero; /* sec 61 #4 */ 187 adj360(&l); 188 Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */ 189 adj360(&Mm); 190 Nm = Nzero - (0.0529539 * days); /* sec 61 #6 */ 191 adj360(&Nm); 192 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */ 193 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */ 194 A3 = 0.37 * sin(dtor(Msol)); 195 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */ 196 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */ 197 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */ 198 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */ 199 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */ 200 ldprime = lprime + V; /* sec 61 #14 */ 201 D = ldprime - LambdaSol; /* sec 63 #2 */ 202 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */ 203} 204 205/* 206 * dtor -- 207 * convert degrees to radians 208 */ 209static double 210dtor(double deg) 211{ 212 213 return(deg * PI / 180); 214} 215 216/* 217 * adj360 -- 218 * adjust value so 0 <= deg <= 360 219 */ 220static void 221adj360(double *deg) 222{ 223 224 for (;;) 225 if (*deg < 0) 226 *deg += 360; 227 else if (*deg > 360) 228 *deg -= 360; 229 else 230 break; 231} 232 233static void 234usage(char *progname) 235{ 236 237 fprintf(stderr, "Usage: %s [-p] [-d yyyy.mm.dd] [-t hh:mm:ss]\n", 238 progname); 239 exit(EX_USAGE); 240} 241