pom.c revision 205821
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/usr.bin/calendar/pom.c 205821 2010-03-29 06:49:20Z edwin $"); 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#include "calendar.h" 69 70#ifndef PI 71#define PI 3.14159265358979323846 72#endif 73#define EPOCH 85 74#define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */ 75#define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */ 76#define ECCEN 0.01671542 /* solar orbit eccentricity */ 77#define lzero 18.251907 /* lunar mean long at EPOCH */ 78#define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */ 79#define Nzero 55.204723 /* lunar mean long of node at EPOCH */ 80#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) 81 82static void adj360(double *); 83static double dtor(double); 84static double potm(double onday); 85static double potm_minute(double onday, int olddir); 86 87void 88pom(int year, double utcoffset, int *fms, int *nms) 89{ 90 double ffms[MAXMOONS]; 91 double fnms[MAXMOONS]; 92 int i, j; 93 94 fpom(year, utcoffset, ffms, fnms); 95 96 j = 0; 97 for (i = 0; ffms[i] != 0; i++) 98 fms[j++] = round(ffms[i]); 99 fms[i] = -1; 100 for (i = 0; fnms[i] != 0; i++) 101 nms[i] = round(fnms[i]); 102 nms[i] = -1; 103} 104 105void 106fpom(int year, double utcoffset, double *ffms, double *fnms) 107{ 108 time_t tt; 109 struct tm GMT, tmd_today, tmd_tomorrow; 110 double days_today, days_tomorrow, today, tomorrow; 111 int cnt, d; 112 int yeardays; 113 int olddir, newdir; 114 double *pfnms, *pffms, t; 115 116 pfnms = fnms; 117 pffms = ffms; 118 119 /* 120 * We take the phase of the moon one second before and one second 121 * after midnight. 122 */ 123 memset(&tmd_today, 0, sizeof(tmd_today)); 124 tmd_today.tm_year = year - 1900; 125 tmd_today.tm_mon = 0; 126 tmd_today.tm_mday = -1; /* 31 December */ 127 tmd_today.tm_hour = 23; 128 tmd_today.tm_min = 59; 129 tmd_today.tm_sec = 59; 130 memset(&tmd_tomorrow, 0, sizeof(tmd_tomorrow)); 131 tmd_tomorrow.tm_year = year - 1900; 132 tmd_tomorrow.tm_mon = 0; 133 tmd_tomorrow.tm_mday = 0; /* 01 January */ 134 tmd_tomorrow.tm_hour = 0; 135 tmd_tomorrow.tm_min = 0; 136 tmd_tomorrow.tm_sec = 1; 137 138 tt = mktime(&tmd_today); 139 gmtime_r(&tt, &GMT); 140 yeardays = 0; 141 for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt) 142 yeardays += isleap(1900 + cnt) ? DAYSPERLEAPYEAR : DAYSPERYEAR; 143 days_today = (GMT.tm_yday + 1) + ((GMT.tm_hour + 144 (GMT.tm_min / FSECSPERMINUTE) + (GMT.tm_sec / FSECSPERHOUR)) / 145 FHOURSPERDAY); 146 days_today += yeardays; 147 148 tt = mktime(&tmd_tomorrow); 149 gmtime_r(&tt, &GMT); 150 yeardays = 0; 151 for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt) 152 yeardays += isleap(1900 + cnt) ? DAYSPERLEAPYEAR : DAYSPERYEAR; 153 days_tomorrow = (GMT.tm_yday + 1) + ((GMT.tm_hour + 154 (GMT.tm_min / FSECSPERMINUTE) + (GMT.tm_sec / FSECSPERHOUR)) / 155 FHOURSPERDAY); 156 days_tomorrow += yeardays; 157 158 today = potm(days_today); /* 30 December 23:59:59 */ 159 tomorrow = potm(days_tomorrow); /* 31 December 00:00:01 */ 160 olddir = today > tomorrow ? -1 : +1; 161 162 yeardays = 1 + isleap(year) ? DAYSPERLEAPYEAR : DAYSPERYEAR; /* reuse */ 163 for (d = 0; d <= yeardays; d++) { 164 today = potm(days_today); 165 tomorrow = potm(days_tomorrow); 166 newdir = today > tomorrow ? -1 : +1; 167 if (olddir != newdir) { 168 t = potm_minute(days_today - 1, olddir) + 169 utcoffset / FHOURSPERDAY; 170 if (olddir == -1 && newdir == +1) { 171 *pfnms = d - 1 + t; 172 pfnms++; 173 } else if (olddir == +1 && newdir == -1) { 174 *pffms = d - 1 + t; 175 pffms++; 176 } 177 } 178 olddir = newdir; 179 days_today++; 180 days_tomorrow++; 181 } 182 *pffms = -1; 183 *pfnms = -1; 184} 185 186static double 187potm_minute(double onday, int olddir) { 188 double period = FSECSPERDAY / 2.0; 189 double p1, p2; 190 double before, after; 191 int newdir; 192 193// printf("---> days:%g olddir:%d\n", days, olddir); 194 195 p1 = onday + (period / SECSPERDAY); 196 period /= 2; 197 198 while (period > 30) { /* half a minute */ 199// printf("period:%g - p1:%g - ", period, p1); 200 p2 = p1 + (2.0 / SECSPERDAY); 201 before = potm(p1); 202 after = potm(p2); 203// printf("before:%10.10g - after:%10.10g\n", before, after); 204 newdir = before < after ? -1 : +1; 205 if (olddir != newdir) 206 p1 += (period / SECSPERDAY); 207 else 208 p1 -= (period / SECSPERDAY); 209 period /= 2; 210// printf("newdir:%d - p1:%10.10f - period:%g\n", 211// newdir, p1, period); 212 } 213 p1 -= floor(p1); 214 //exit(0); 215 return (p1); 216} 217 218/* 219 * potm -- 220 * return phase of the moon, as a percentage [0 ... 100] 221 */ 222static double 223potm(double onday) 224{ 225 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; 226 double A4, lprime, V, ldprime, D, Nm; 227 228 N = 360 * onday / 365.2422; /* sec 42 #3 */ 229 adj360(&N); 230 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */ 231 adj360(&Msol); 232 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */ 233 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */ 234 adj360(&LambdaSol); 235 l = 13.1763966 * onday + lzero; /* sec 61 #4 */ 236 adj360(&l); 237 Mm = l - (0.1114041 * onday) - Pzero; /* sec 61 #5 */ 238 adj360(&Mm); 239 Nm = Nzero - (0.0529539 * onday); /* sec 61 #6 */ 240 adj360(&Nm); 241 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */ 242 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */ 243 A3 = 0.37 * sin(dtor(Msol)); 244 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */ 245 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */ 246 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */ 247 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */ 248 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */ 249 ldprime = lprime + V; /* sec 61 #14 */ 250 D = ldprime - LambdaSol; /* sec 63 #2 */ 251 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */ 252} 253 254/* 255 * dtor -- 256 * convert degrees to radians 257 */ 258static double 259dtor(double deg) 260{ 261 262 return(deg * PI / 180); 263} 264 265/* 266 * adj360 -- 267 * adjust value so 0 <= deg <= 360 268 */ 269static void 270adj360(double *deg) 271{ 272 273 for (;;) 274 if (*deg < 0) 275 *deg += 360; 276 else if (*deg > 360) 277 *deg -= 360; 278 else 279 break; 280} 281