pom.c revision 1.7
1 /* $NetBSD: pom.c,v 1.7 1997/10/10 16:47:05 lukem 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 1.7 1997/10/10 16:47:05 lukem 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 <errno.h> 64 #include <math.h> 65 #include <stdio.h> 66 #include <string.h> 67 #include <tzfile.h> 68 69 #define PI 3.141592654 70 #define EPOCH 85 71 #define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */ 72 #define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */ 73 #define ECCEN 0.01671542 /* solar orbit eccentricity */ 74 #define lzero 18.251907 /* lunar mean long at EPOCH */ 75 #define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */ 76 #define Nzero 55.204723 /* lunar mean long of node at EPOCH */ 77 78 void adj360 __P((double *)); 79 double dtor __P((double)); 80 int main __P((int, char *[])); 81 double potm __P((double)); 82 83 int 84 main(argc, argv) 85 int argc; 86 char *argv[]; 87 { 88 struct timeval tp; 89 struct timezone tzp; 90 struct tm *GMT; 91 time_t tmpt; 92 double days, today, tomorrow; 93 int cnt; 94 95 if (gettimeofday(&tp,&tzp)) { 96 (void)fprintf(stderr, "pom: %s\n", strerror(errno)); 97 exit(1); 98 } 99 tmpt = tp.tv_sec; 100 GMT = gmtime(&tmpt); 101 days = (GMT->tm_yday + 1) + ((GMT->tm_hour + 102 (GMT->tm_min / 60.0) + (GMT->tm_sec / 3600.0)) / 24.0); 103 for (cnt = EPOCH; cnt < GMT->tm_year; ++cnt) 104 days += isleap(cnt) ? 366 : 365; 105 today = potm(days) + .5; 106 (void)printf("The Moon is "); 107 if ((int)today == 100) 108 (void)printf("Full\n"); 109 else if (!(int)today) 110 (void)printf("New\n"); 111 else { 112 tomorrow = potm(days + 1); 113 if ((int)today == 50) 114 (void)printf("%s\n", tomorrow > today ? 115 "at the First Quarter" : "at the Last Quarter"); 116 else { 117 (void)printf("%s ", tomorrow > today ? 118 "Waxing" : "Waning"); 119 if (today > 50) 120 (void)printf("Gibbous (%1.0f%% of Full)\n", 121 today); 122 else if (today < 50) 123 (void)printf("Crescent (%1.0f%% of Full)\n", 124 today); 125 } 126 } 127 exit(0); 128 } 129 130 /* 131 * potm -- 132 * return phase of the moon 133 */ 134 double 135 potm(days) 136 double days; 137 { 138 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; 139 double A4, lprime, V, ldprime, D, Nm; 140 141 N = 360 * days / 365.2422; /* sec 42 #3 */ 142 adj360(&N); 143 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */ 144 adj360(&Msol); 145 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */ 146 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */ 147 adj360(&LambdaSol); 148 l = 13.1763966 * days + lzero; /* sec 61 #4 */ 149 adj360(&l); 150 Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */ 151 adj360(&Mm); 152 Nm = Nzero - (0.0529539 * days); /* sec 61 #6 */ 153 adj360(&Nm); 154 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */ 155 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */ 156 A3 = 0.37 * sin(dtor(Msol)); 157 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */ 158 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */ 159 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */ 160 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */ 161 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */ 162 ldprime = lprime + V; /* sec 61 #14 */ 163 D = ldprime - LambdaSol; /* sec 63 #2 */ 164 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */ 165 } 166 167 /* 168 * dtor -- 169 * convert degrees to radians 170 */ 171 double 172 dtor(deg) 173 double deg; 174 { 175 return(deg * PI / 180); 176 } 177 178 /* 179 * adj360 -- 180 * adjust value so 0 <= deg <= 360 181 */ 182 void 183 adj360(deg) 184 double *deg; 185 { 186 for (;;) 187 if (*deg < 0) 188 *deg += 360; 189 else if (*deg > 360) 190 *deg -= 360; 191 else 192 break; 193 } 194
Indexes created Wed Oct 01 19:09:53 GMT 2025