pom.c revision 1.5
1 /* $NetBSD: pom.c,v 1.5 1995/06/07 16:30:46 cgd 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 #ifndef lint 39 static char copyright[] = 40 "@(#) 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 static char rcsid[] = "$NetBSD: pom.c,v 1.5 1995/06/07 16:30:46 cgd 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 <stdio.h> 64 #include <string.h> 65 #include <tzfile.h> 66 #include <math.h> 67 68 #define PI 3.141592654 69 #define EPOCH 85 70 #define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */ 71 #define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */ 72 #define ECCEN 0.01671542 /* solar orbit eccentricity */ 73 #define lzero 18.251907 /* lunar mean long at EPOCH */ 74 #define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */ 75 #define Nzero 55.204723 /* lunar mean long of node at EPOCH */ 76 77 double dtor(), potm(), adj360(); 78 79 main() 80 { 81 extern int errno; 82 struct timeval tp; 83 struct timezone tzp; 84 struct tm *GMT, *gmtime(); 85 time_t tmpt; 86 double days, today, tomorrow; 87 int cnt; 88 89 if (gettimeofday(&tp,&tzp)) { 90 (void)fprintf(stderr, "pom: %s\n", strerror(errno)); 91 exit(1); 92 } 93 tmpt = tp.tv_sec; 94 GMT = gmtime(&tmpt); 95 days = (GMT->tm_yday + 1) + ((GMT->tm_hour + 96 (GMT->tm_min / 60.0) + (GMT->tm_sec / 3600.0)) / 24.0); 97 for (cnt = EPOCH; cnt < GMT->tm_year; ++cnt) 98 days += isleap(cnt) ? 366 : 365; 99 today = potm(days) + .5; 100 (void)printf("The Moon is "); 101 if ((int)today == 100) 102 (void)printf("Full\n"); 103 else if (!(int)today) 104 (void)printf("New\n"); 105 else { 106 tomorrow = potm(days + 1); 107 if ((int)today == 50) 108 (void)printf("%s\n", tomorrow > today ? 109 "at the First Quarter" : "at the Last Quarter"); 110 else { 111 (void)printf("%s ", tomorrow > today ? 112 "Waxing" : "Waning"); 113 if (today > 50) 114 (void)printf("Gibbous (%1.0f%% of Full)\n", 115 today); 116 else if (today < 50) 117 (void)printf("Crescent (%1.0f%% of Full)\n", 118 today); 119 } 120 } 121 exit(0); 122 } 123 124 /* 125 * potm -- 126 * return phase of the moon 127 */ 128 double 129 potm(days) 130 double days; 131 { 132 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; 133 double A4, lprime, V, ldprime, D, Nm; 134 135 N = 360 * days / 365.2422; /* sec 42 #3 */ 136 adj360(&N); 137 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */ 138 adj360(&Msol); 139 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */ 140 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */ 141 adj360(&LambdaSol); 142 l = 13.1763966 * days + lzero; /* sec 61 #4 */ 143 adj360(&l); 144 Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */ 145 adj360(&Mm); 146 Nm = Nzero - (0.0529539 * days); /* sec 61 #6 */ 147 adj360(&Nm); 148 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */ 149 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */ 150 A3 = 0.37 * sin(dtor(Msol)); 151 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */ 152 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */ 153 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */ 154 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */ 155 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */ 156 ldprime = lprime + V; /* sec 61 #14 */ 157 D = ldprime - LambdaSol; /* sec 63 #2 */ 158 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */ 159 } 160 161 /* 162 * dtor -- 163 * convert degrees to radians 164 */ 165 double 166 dtor(deg) 167 double deg; 168 { 169 return(deg * PI / 180); 170 } 171 172 /* 173 * adj360 -- 174 * adjust value so 0 <= deg <= 360 175 */ 176 double 177 adj360(deg) 178 double *deg; 179 { 180 for (;;) 181 if (*deg < 0) 182 *deg += 360; 183 else if (*deg > 360) 184 *deg -= 360; 185 else 186 break; 187 } 188
Indexes created Wed Oct 01 15:09:59 GMT 2025