/* $OpenBSD: pom.c,v 1.14 2009/12/31 13:02:08 sobrado Exp $ */ /* $NetBSD: pom.c,v 1.6 1996/02/06 22:47:29 jtc 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. */ /* * 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, IX 1998 * */ #include <sys/time.h> #include <sys/types.h> #include <ctype.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h> #include <err.h> #include <tzfile.h> #include <unistd.h> #ifndef M_PI #define M_PI 3.14159265358979323846 #endif #define EPOCH 90 #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 */ void adj360(double *); double dtor(double); double potm(double); time_t parsetime(char *); void badformat(void); int main(int argc, char *argv[]) { struct timeval tp; struct timezone tzp; struct tm *GMT; time_t tmpt; double days, today, tomorrow; int cnt; char buf[1024]; 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 { if (gettimeofday(&tp,&tzp)) err(1, "gettimeofday"); tmpt = tp.tv_sec; } GMT = gmtime(&tmpt); days = (GMT->tm_yday + 1) + ((GMT->tm_hour + (GMT->tm_min / 60.0) + (GMT->tm_sec / 3600.0)) / 24.0); for (cnt = EPOCH; cnt < GMT->tm_year; ++cnt) days += isleap(cnt + TM_YEAR_BASE) ? 366 : 365; /* Selected time could be before EPOCH */ for (cnt = GMT->tm_year; cnt < EPOCH; ++cnt) days -= isleap(cnt + TM_YEAR_BASE) ? 366 : 365; today = potm(days) + 0.5; (void)printf("The Moon is "); 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); } } exit(0); } /* * potm -- * return phase of the moon */ double potm(double days) { double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime; double A4, lprime, V, ldprime, D, Nm; N = 360.0 * days / 365.242191; /* sec 46 #3 */ adj360(&N); Msol = N + EPSILONg - RHOg; /* sec 46 #4 */ adj360(&Msol); Ec = 360 / M_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 */ double dtor(double deg) { return(deg * M_PI / 180); } /* * adj360 -- * adjust value so 0 <= deg <= 360 */ void adj360(double *deg) { for (;;) if (*deg < 0.0) *deg += 360.0; else if (*deg > 360.0) *deg -= 360.0; else break; } #define ATOI2(ar) ((ar)[0] - '0') * 10 + ((ar)[1] - '0'); (ar) += 2; 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(*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 - TM_YEAR_BASE; yearset = 1; /* FALLTHROUGH */ case 8: /* yy */ if (yearset) { lt->tm_year += ATOI2(p); } else { lt->tm_year = ATOI2(p) + 1900 - TM_YEAR_BASE; 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); } void badformat(void) { warnx("illegal time format"); (void)fprintf(stderr, "usage: pom [[[[[cc]yy]mm]dd]HH]\n"); exit(1); }