/* $NetBSD: pom.c,v 1.20 2010/12/05 04:34:22 pgoyette Exp $ */ /* * 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. * 3. 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. */ #include #ifndef lint __COPYRIGHT("@(#) Copyright (c) 1989, 1993\ The Regents of the University of California. All rights reserved."); #endif /* not lint */ #ifndef lint #if 0 static char sccsid[] = "@(#)pom.c 8.1 (Berkeley) 5/31/93"; #else __RCSID("$NetBSD: pom.c,v 1.20 2010/12/05 04:34:22 pgoyette Exp $"); #endif #endif /* not lint */ /* * 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 * * Updated to the Third Edition of Duffett-Smith's book, Paul Janzen, IX 1998 * */ #include #include #include #include #include #include #include #include #ifndef PI #define PI 3.14159265358979323846 #endif /* * The EPOCH in the third edition of the book is 1990 Jan 0.0 TDT. * In this program, we do not bother to correct for the differences * between UTC (as shown by the UNIX clock) and TDT. (TDT = TAI + 32.184s; * TAI-UTC = 32s in Jan 1999.) */ #define EPOCH_MINUS_1970 (20 * 365 + 5 - 1) /* 20 years, 5 leaps, back 1 day to Jan 0 */ #define EPSILONg 279.403303 /* solar ecliptic long at EPOCH */ #define RHOg 282.768422 /* solar ecliptic long of perigee at EPOCH */ #define ECCEN 0.016713 /* solar orbit eccentricity */ #define lzero 318.351648 /* lunar mean long at EPOCH */ #define Pzero 36.340410 /* lunar mean long of perigee at EPOCH */ #define Nzero 318.510107 /* lunar mean long of node at EPOCH */ int main(int, char *[]); static void adj360(double *); static double dtor(double); static double potm(double); static time_t parsetime(char *); static void badformat(void) __dead; int main(int argc, char *argv[]) { time_t tmpt, now; double days, today, tomorrow; char buf[1024]; if (time(&now) == (time_t)-1) err(1, "time"); if (argc > 1) { tmpt = parsetime(argv[1]); strftime(buf, sizeof(buf), "%a %Y %b %e %H:%M:%S (%Z)", localtime(&tmpt)); printf("%s: ", buf); } else { tmpt = now; } days = (tmpt - EPOCH_MINUS_1970 * 86400) / 86400.0; today = potm(days) + .5; if (tmpt < now) (void)printf("The Moon was "); else if (tmpt == now) (void)printf("The Moon is "); else (void)printf("The Moon will be "); if ((int)today == 100) (void)printf("Full\n"); else if (!(int)today) (void)printf("New\n"); else { tomorrow = potm(days + 1); if ((int)today == 50) (void)printf("%s\n", tomorrow > today ? "at the First Quarter" : "at the Last Quarter"); /* today is 0.5 too big, but it doesn't matter here * since the phase is changing fast enough */ else { today -= 0.5; /* Now it might matter */ (void)printf("%s ", tomorrow > today ? "Waxing" : "Waning"); if (today > 50) (void)printf("Gibbous (%1.0f%% of Full)\n", today); else if (today < 50) (void)printf("Crescent (%1.0f%% of Full)\n", today); } } return EXIT_SUCCESS; } /* * potm -- * return phase of the moon */ static double potm(double days) { double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; double A4, lprime, V, ldprime, D, Nm; N = 360 * days / 365.242191; /* sec 46 #3 */ adj360(&N); Msol = N + EPSILONg - RHOg; /* sec 46 #4 */ adj360(&Msol); Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 46 #5 */ LambdaSol = N + Ec + EPSILONg; /* sec 46 #6 */ adj360(&LambdaSol); l = 13.1763966 * days + lzero; /* sec 65 #4 */ adj360(&l); Mm = l - (0.1114041 * days) - Pzero; /* sec 65 #5 */ adj360(&Mm); Nm = Nzero - (0.0529539 * days); /* sec 65 #6 */ adj360(&Nm); Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 65 #7 */ Ac = 0.1858 * sin(dtor(Msol)); /* sec 65 #8 */ A3 = 0.37 * sin(dtor(Msol)); Mmprime = Mm + Ev - Ac - A3; /* sec 65 #9 */ Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 65 #10 */ A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 65 #11 */ lprime = l + Ev + Ec - Ac + A4; /* sec 65 #12 */ V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 65 #13 */ ldprime = lprime + V; /* sec 65 #14 */ D = ldprime - LambdaSol; /* sec 67 #2 */ return(50.0 * (1 - cos(dtor(D)))); /* sec 67 #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; } #define ATOI2(ar) ((ar)[0] - '0') * 10 + ((ar)[1] - '0'); (ar) += 2; static time_t parsetime(char *p) { struct tm *lt; int bigyear; int yearset = 0; time_t tval; char *t; for (t = p; *t; ++t) { if (isdigit((unsigned char) *t)) continue; badformat(); } tval = time(NULL); lt = localtime(&tval); lt->tm_sec = 0; lt->tm_min = 0; switch (strlen(p)) { case 10: /* yyyy */ bigyear = ATOI2(p); lt->tm_year = bigyear * 100 - 1900; yearset = 1; /* FALLTHROUGH */ case 8: /* yy */ if (yearset) { lt->tm_year += ATOI2(p); } else { lt->tm_year = ATOI2(p); if (lt->tm_year < 69) /* hack for 2000 */ lt->tm_year += 100; } /* FALLTHROUGH */ case 6: /* mm */ lt->tm_mon = ATOI2(p); if ((lt->tm_mon > 12) || !lt->tm_mon) badformat(); --lt->tm_mon; /* time struct is 0 - 11 */ /* FALLTHROUGH */ case 4: /* dd */ lt->tm_mday = ATOI2(p); if ((lt->tm_mday > 31) || !lt->tm_mday) badformat(); /* FALLTHROUGH */ case 2: /* HH */ lt->tm_hour = ATOI2(p); if (lt->tm_hour > 23) badformat(); break; default: badformat(); } /* The calling code needs a valid tm_ydays and this is the easiest * way to get one */ if ((tval = mktime(lt)) == -1) errx(1, "specified date is outside allowed range"); return (tval); } static void badformat(void) { warnx("illegal time format"); (void)fprintf(stderr, "usage: %s [[[[[cc]yy]mm]dd]HH]\n", getprogname()); exit(EXIT_FAILURE); }