/* * Copyright (c) 1989, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software posted to USENET. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #if 0 #ifndef lint static const char copyright[] = "@(#) Copyright (c) 1989, 1993\n\ The Regents of the University of California. All rights reserved.\n"; #endif /* not lint */ #ifndef lint static const char sccsid[] = "@(#)pom.c 8.1 (Berkeley) 5/31/93"; #endif /* not lint */ #endif #include __FBSDID("$FreeBSD$"); /* * Phase of the Moon. Calculates the current phase of the moon. * Based on routines from `Practical Astronomy with Your Calculator', * by Duffett-Smith. Comments give the section from the book that * particular piece of code was adapted from. * * -- Keith E. Brandt VIII 1984 * */ #include #include #include #include #include #include #include #include "calendar.h" #ifndef PI #define PI 3.14159265358979323846 #endif #define EPOCH 85 #define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */ #define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */ #define ECCEN 0.01671542 /* solar orbit eccentricity */ #define lzero 18.251907 /* lunar mean long at EPOCH */ #define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */ #define Nzero 55.204723 /* lunar mean long of node at EPOCH */ #define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) static void adj360(double *); static double dtor(double); static double potm(double onday); static double potm_minute(double onday, int olddir); void pom(int year, double utcoffset, int *fms, int *nms) { double ffms[MAXMOONS]; double fnms[MAXMOONS]; int i, j; fpom(year, utcoffset, ffms, fnms); j = 0; for (i = 0; ffms[i] != 0; i++) fms[j++] = round(ffms[i]); fms[i] = -1; for (i = 0; fnms[i] != 0; i++) nms[i] = round(fnms[i]); nms[i] = -1; } void fpom(int year, double utcoffset, double *ffms, double *fnms) { time_t tt; struct tm GMT, tmd_today, tmd_tomorrow; double days_today, days_tomorrow, today, tomorrow; int cnt, d; int yeardays; int olddir, newdir; double *pfnms, *pffms, t; pfnms = fnms; pffms = ffms; /* * We take the phase of the moon one second before and one second * after midnight. */ memset(&tmd_today, 0, sizeof(tmd_today)); tmd_today.tm_year = year - 1900; tmd_today.tm_mon = 0; tmd_today.tm_mday = -1; /* 31 December */ tmd_today.tm_hour = 23; tmd_today.tm_min = 59; tmd_today.tm_sec = 59; memset(&tmd_tomorrow, 0, sizeof(tmd_tomorrow)); tmd_tomorrow.tm_year = year - 1900; tmd_tomorrow.tm_mon = 0; tmd_tomorrow.tm_mday = 0; /* 01 January */ tmd_tomorrow.tm_hour = 0; tmd_tomorrow.tm_min = 0; tmd_tomorrow.tm_sec = 1; tt = mktime(&tmd_today); gmtime_r(&tt, &GMT); yeardays = 0; for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt) yeardays += isleap(1900 + cnt) ? DAYSPERLEAPYEAR : DAYSPERYEAR; days_today = (GMT.tm_yday + 1) + ((GMT.tm_hour + (GMT.tm_min / FSECSPERMINUTE) + (GMT.tm_sec / FSECSPERHOUR)) / FHOURSPERDAY); days_today += yeardays; tt = mktime(&tmd_tomorrow); gmtime_r(&tt, &GMT); yeardays = 0; for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt) yeardays += isleap(1900 + cnt) ? DAYSPERLEAPYEAR : DAYSPERYEAR; days_tomorrow = (GMT.tm_yday + 1) + ((GMT.tm_hour + (GMT.tm_min / FSECSPERMINUTE) + (GMT.tm_sec / FSECSPERHOUR)) / FHOURSPERDAY); days_tomorrow += yeardays; today = potm(days_today); /* 30 December 23:59:59 */ tomorrow = potm(days_tomorrow); /* 31 December 00:00:01 */ olddir = today > tomorrow ? -1 : +1; yeardays = 1 + (isleap(year) ? DAYSPERLEAPYEAR : DAYSPERYEAR); /* reuse */ for (d = 0; d <= yeardays; d++) { today = potm(days_today); tomorrow = potm(days_tomorrow); newdir = today > tomorrow ? -1 : +1; if (olddir != newdir) { t = potm_minute(days_today - 1, olddir) + utcoffset / FHOURSPERDAY; if (olddir == -1 && newdir == +1) { *pfnms = d - 1 + t; pfnms++; } else if (olddir == +1 && newdir == -1) { *pffms = d - 1 + t; pffms++; } } olddir = newdir; days_today++; days_tomorrow++; } *pffms = -1; *pfnms = -1; } static double potm_minute(double onday, int olddir) { double period = FSECSPERDAY / 2.0; double p1, p2; double before, after; int newdir; // printf("---> days:%g olddir:%d\n", days, olddir); p1 = onday + (period / SECSPERDAY); period /= 2; while (period > 30) { /* half a minute */ // printf("period:%g - p1:%g - ", period, p1); p2 = p1 + (2.0 / SECSPERDAY); before = potm(p1); after = potm(p2); // printf("before:%10.10g - after:%10.10g\n", before, after); newdir = before < after ? -1 : +1; if (olddir != newdir) p1 += (period / SECSPERDAY); else p1 -= (period / SECSPERDAY); period /= 2; // printf("newdir:%d - p1:%10.10f - period:%g\n", // newdir, p1, period); } p1 -= floor(p1); //exit(0); return (p1); } /* * potm -- * return phase of the moon, as a percentage [0 ... 100] */ static double potm(double onday) { double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; double A4, lprime, V, ldprime, D, Nm; N = 360 * onday / 365.2422; /* sec 42 #3 */ adj360(&N); Msol = N + EPSILONg - RHOg; /* sec 42 #4 */ adj360(&Msol); Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */ LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */ adj360(&LambdaSol); l = 13.1763966 * onday + lzero; /* sec 61 #4 */ adj360(&l); Mm = l - (0.1114041 * onday) - Pzero; /* sec 61 #5 */ adj360(&Mm); Nm = Nzero - (0.0529539 * onday); /* sec 61 #6 */ adj360(&Nm); Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */ Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */ A3 = 0.37 * sin(dtor(Msol)); Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */ Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */ A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */ lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */ V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */ ldprime = lprime + V; /* sec 61 #14 */ D = ldprime - LambdaSol; /* sec 63 #2 */ return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */ } /* * dtor -- * convert degrees to radians */ static double dtor(double deg) { return(deg * PI / 180); } /* * adj360 -- * adjust value so 0 <= deg <= 360 */ static void adj360(double *deg) { for (;;) if (*deg < 0) *deg += 360; else if (*deg > 360) *deg -= 360; else break; }