pom.c revision 1.11
1 /* $NetBSD: pom.c,v 1.11 1998/09/11 14:07:04 hubertf Exp $ */ 2 3 /* 4 * Copyright (c) 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software posted to USENET. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by the University of 20 * California, Berkeley and its contributors. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 */ 37 38 #include <sys/cdefs.h> 39 #ifndef lint 40 __COPYRIGHT("@(#) Copyright (c) 1989, 1993\n\ 41 The Regents of the University of California. All rights reserved.\n"); 42 #endif /* not lint */ 43 44 #ifndef lint 45 #if 0 46 static char sccsid[] = "@(#)pom.c 8.1 (Berkeley) 5/31/93"; 47 #else 48 __RCSID("$NetBSD: pom.c,v 1.11 1998/09/11 14:07:04 hubertf Exp $"); 49 #endif 50 #endif /* not lint */ 51 52 /* 53 * Phase of the Moon. Calculates the current phase of the moon. 54 * Based on routines from `Practical Astronomy with Your Calculator', 55 * by Duffett-Smith. Comments give the section from the book that 56 * particular piece of code was adapted from. 57 * 58 * -- Keith E. Brandt VIII 1984 59 * 60 */ 61 62 #include <sys/time.h> 63 #include <err.h> 64 #include <errno.h> 65 #include <math.h> 66 #include <stdio.h> 67 #include <string.h> 68 #include <stdlib.h> 69 #include <tzfile.h> 70 71 #ifndef PI 72 #define PI 3.14159265358979323846 73 #endif 74 #define EPOCH 85 /* really 1985 */ 75 #define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */ 76 #define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */ 77 #define ECCEN 0.01671542 /* solar orbit eccentricity */ 78 #define lzero 18.251907 /* lunar mean long at EPOCH */ 79 #define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */ 80 #define Nzero 55.204723 /* lunar mean long of node at EPOCH */ 81 82 void adj360 __P((double *)); 83 double dtor __P((double)); 84 int main __P((int, char *[])); 85 double potm __P((double)); 86 87 int 88 main(argc, argv) 89 int argc; 90 char *argv[]; 91 { 92 struct timeval tp; 93 struct timezone tzp; 94 struct tm *GMT; 95 time_t tmpt; 96 double days, today, tomorrow; 97 int cnt; 98 99 if (argc > 1) { 100 tp.tv_sec = atoi(argv[1]); 101 tp.tv_usec = 0; 102 } else { 103 if (gettimeofday(&tp,&tzp)) 104 err(1, "gettimeofday"); 105 } 106 tmpt = tp.tv_sec; 107 GMT = gmtime(&tmpt); 108 days = (GMT->tm_yday + 1) + ((GMT->tm_hour + 109 (GMT->tm_min / 60.0) + (GMT->tm_sec / 3600.0)) / 24.0); 110 for (cnt = EPOCH; cnt < GMT->tm_year; ++cnt) 111 days += isleap(cnt + 1900) ? 366 : 365; 112 today = potm(days) + .5; 113 (void)printf("The Moon is "); 114 if ((int)today == 100) 115 (void)printf("Full\n"); 116 else if (!(int)today) 117 (void)printf("New\n"); 118 else { 119 tomorrow = potm(days + 1); 120 if ((int)today == 50) 121 (void)printf("%s\n", tomorrow > today ? 122 "at the First Quarter" : "at the Last Quarter"); 123 else { 124 (void)printf("%s ", tomorrow > today ? 125 "Waxing" : "Waning"); 126 if (today > 50) 127 (void)printf("Gibbous (%1.0f%% of Full)\n", 128 today); 129 else if (today < 50) 130 (void)printf("Crescent (%1.0f%% of Full)\n", 131 today); 132 } 133 } 134 exit(0); 135 } 136 137 /* 138 * potm -- 139 * return phase of the moon 140 */ 141 double 142 potm(days) 143 double days; 144 { 145 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; 146 double A4, lprime, V, ldprime, D, Nm; 147 148 N = 360 * days / 365.2422; /* sec 42 #3 */ 149 adj360(&N); 150 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */ 151 adj360(&Msol); 152 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */ 153 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */ 154 adj360(&LambdaSol); 155 l = 13.1763966 * days + lzero; /* sec 61 #4 */ 156 adj360(&l); 157 Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */ 158 adj360(&Mm); 159 Nm = Nzero - (0.0529539 * days); /* sec 61 #6 */ 160 adj360(&Nm); 161 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */ 162 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */ 163 A3 = 0.37 * sin(dtor(Msol)); 164 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */ 165 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */ 166 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */ 167 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */ 168 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */ 169 ldprime = lprime + V; /* sec 61 #14 */ 170 D = ldprime - LambdaSol; /* sec 63 #2 */ 171 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */ 172 } 173 174 /* 175 * dtor -- 176 * convert degrees to radians 177 */ 178 double 179 dtor(deg) 180 double deg; 181 { 182 return(deg * PI / 180); 183 } 184 185 /* 186 * adj360 -- 187 * adjust value so 0 <= deg <= 360 188 */ 189 void 190 adj360(deg) 191 double *deg; 192 { 193 for (;;) 194 if (*deg < 0) 195 *deg += 360; 196 else if (*deg > 360) 197 *deg -= 360; 198 else 199 break; 200 } 201
Indexes created Thu Oct 02 07:10:07 GMT 2025