1/*- 2 * SPDX-License-Identifier: BSD-3-Clause 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. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34/* 35 * Phase of the Moon. Calculates the current phase of the moon. 36 * Based on routines from `Practical Astronomy with Your Calculator', 37 * by Duffett-Smith. Comments give the section from the book that 38 * particular piece of code was adapted from. 39 * 40 * -- Keith E. Brandt VIII 1984 41 * 42 */ 43 44#include <stdio.h> 45#include <stdlib.h> 46#include <math.h> 47#include <string.h> 48#include <sysexits.h> 49#include <time.h> 50#include <unistd.h> 51 52#include "calendar.h" 53 54#ifndef PI 55#define PI 3.14159265358979323846 56#endif 57#define EPOCH 85 58#define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */ 59#define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */ 60#define ECCEN 0.01671542 /* solar orbit eccentricity */ 61#define lzero 18.251907 /* lunar mean long at EPOCH */ 62#define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */ 63#define Nzero 55.204723 /* lunar mean long of node at EPOCH */ 64#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) 65 66static void adj360(double *); 67static double dtor(double); 68static double potm(double onday); 69static double potm_minute(double onday, int olddir); 70 71void 72pom(int year, double utcoffset, int *fms, int *nms) 73{ 74 double ffms[MAXMOONS]; 75 double fnms[MAXMOONS]; 76 int i, j; 77 78 fpom(year, utcoffset, ffms, fnms); 79 80 j = 0; 81 for (i = 0; ffms[i] != 0; i++) 82 fms[j++] = round(ffms[i]); 83 fms[i] = -1; 84 for (i = 0; fnms[i] != 0; i++) 85 nms[i] = round(fnms[i]); 86 nms[i] = -1; 87} 88 89void 90fpom(int year, double utcoffset, double *ffms, double *fnms) 91{ 92 time_t tt; 93 struct tm GMT, tmd_today, tmd_tomorrow; 94 double days_today, days_tomorrow, today, tomorrow; 95 int cnt, d; 96 int yeardays; 97 int olddir, newdir; 98 double *pfnms, *pffms, t; 99 100 pfnms = fnms; 101 pffms = ffms; 102 103 /* 104 * We take the phase of the moon one second before and one second 105 * after midnight. 106 */ 107 memset(&tmd_today, 0, sizeof(tmd_today)); 108 tmd_today.tm_year = year - 1900; 109 tmd_today.tm_mon = 0; 110 tmd_today.tm_mday = -1; /* 31 December */ 111 tmd_today.tm_hour = 23; 112 tmd_today.tm_min = 59; 113 tmd_today.tm_sec = 59; 114 memset(&tmd_tomorrow, 0, sizeof(tmd_tomorrow)); 115 tmd_tomorrow.tm_year = year - 1900; 116 tmd_tomorrow.tm_mon = 0; 117 tmd_tomorrow.tm_mday = 0; /* 01 January */ 118 tmd_tomorrow.tm_hour = 0; 119 tmd_tomorrow.tm_min = 0; 120 tmd_tomorrow.tm_sec = 1; 121 122 tt = mktime(&tmd_today); 123 gmtime_r(&tt, &GMT); 124 yeardays = 0; 125 for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt) 126 yeardays += isleap(1900 + cnt) ? DAYSPERLEAPYEAR : DAYSPERYEAR; 127 days_today = (GMT.tm_yday + 1) + ((GMT.tm_hour + 128 (GMT.tm_min / FSECSPERMINUTE) + (GMT.tm_sec / FSECSPERHOUR)) / 129 FHOURSPERDAY); 130 days_today += yeardays; 131 132 tt = mktime(&tmd_tomorrow); 133 gmtime_r(&tt, &GMT); 134 yeardays = 0; 135 for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt) 136 yeardays += isleap(1900 + cnt) ? DAYSPERLEAPYEAR : DAYSPERYEAR; 137 days_tomorrow = (GMT.tm_yday + 1) + ((GMT.tm_hour + 138 (GMT.tm_min / FSECSPERMINUTE) + (GMT.tm_sec / FSECSPERHOUR)) / 139 FHOURSPERDAY); 140 days_tomorrow += yeardays; 141 142 today = potm(days_today); /* 30 December 23:59:59 */ 143 tomorrow = potm(days_tomorrow); /* 31 December 00:00:01 */ 144 olddir = today > tomorrow ? -1 : +1; 145 146 yeardays = 1 + (isleap(year) ? DAYSPERLEAPYEAR : DAYSPERYEAR); /* reuse */ 147 for (d = 0; d <= yeardays; d++) { 148 today = potm(days_today); 149 tomorrow = potm(days_tomorrow); 150 newdir = today > tomorrow ? -1 : +1; 151 if (olddir != newdir) { 152 t = potm_minute(days_today - 1, olddir) + 153 utcoffset / FHOURSPERDAY; 154 if (olddir == -1 && newdir == +1) { 155 *pfnms = d - 1 + t; 156 pfnms++; 157 } else if (olddir == +1 && newdir == -1) { 158 *pffms = d - 1 + t; 159 pffms++; 160 } 161 } 162 olddir = newdir; 163 days_today++; 164 days_tomorrow++; 165 } 166 *pffms = -1; 167 *pfnms = -1; 168} 169 170static double 171potm_minute(double onday, int olddir) { 172 double period = FSECSPERDAY / 2.0; 173 double p1, p2; 174 double before, after; 175 int newdir; 176 177// printf("---> days:%g olddir:%d\n", days, olddir); 178 179 p1 = onday + (period / SECSPERDAY); 180 period /= 2; 181 182 while (period > 30) { /* half a minute */ 183// printf("period:%g - p1:%g - ", period, p1); 184 p2 = p1 + (2.0 / SECSPERDAY); 185 before = potm(p1); 186 after = potm(p2); 187// printf("before:%10.10g - after:%10.10g\n", before, after); 188 newdir = before < after ? -1 : +1; 189 if (olddir != newdir) 190 p1 += (period / SECSPERDAY); 191 else 192 p1 -= (period / SECSPERDAY); 193 period /= 2; 194// printf("newdir:%d - p1:%10.10f - period:%g\n", 195// newdir, p1, period); 196 } 197 p1 -= floor(p1); 198 //exit(0); 199 return (p1); 200} 201 202/* 203 * potm -- 204 * return phase of the moon, as a percentage [0 ... 100] 205 */ 206static double 207potm(double onday) 208{ 209 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; 210 double A4, lprime, V, ldprime, D, Nm; 211 212 N = 360 * onday / 365.2422; /* sec 42 #3 */ 213 adj360(&N); 214 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */ 215 adj360(&Msol); 216 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */ 217 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */ 218 adj360(&LambdaSol); 219 l = 13.1763966 * onday + lzero; /* sec 61 #4 */ 220 adj360(&l); 221 Mm = l - (0.1114041 * onday) - Pzero; /* sec 61 #5 */ 222 adj360(&Mm); 223 Nm = Nzero - (0.0529539 * onday); /* sec 61 #6 */ 224 adj360(&Nm); 225 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */ 226 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */ 227 A3 = 0.37 * sin(dtor(Msol)); 228 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */ 229 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */ 230 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */ 231 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */ 232 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */ 233 ldprime = lprime + V; /* sec 61 #14 */ 234 D = ldprime - LambdaSol; /* sec 63 #2 */ 235 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */ 236} 237 238/* 239 * dtor -- 240 * convert degrees to radians 241 */ 242static double 243dtor(double deg) 244{ 245 246 return(deg * PI / 180); 247} 248 249/* 250 * adj360 -- 251 * adjust value so 0 <= deg <= 360 252 */ 253static void 254adj360(double *deg) 255{ 256 257 for (;;) 258 if (*deg < 0) 259 *deg += 360; 260 else if (*deg > 360) 261 *deg -= 360; 262 else 263 break; 264} 265