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- /*
- * Copyright (c) 1989 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. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * This product includes software developed by the University of
- * California, Berkeley and its contributors.
- * 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.
- */
-
- #ifndef lint
- char copyright[] =
- "@(#) Copyright (c) 1989 The Regents of the University of California.\n\
- All rights reserved.\n";
- #endif /* not lint */
-
- #ifndef lint
- static char sccsid[] = "@(#)pom.c 5.3 (Berkeley) 2/28/91";
- #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
- *
- */
-
- #include <sys/time.h>
- #include <stdio.h>
- #include <tzfile.h>
- #include <math.h>
-
- #define PI 3.141592654
- #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 */
-
- double dtor(), potm(), adj360();
-
- main()
- {
- extern int errno;
- struct timeval tp;
- struct timezone tzp;
- struct tm *GMT, *gmtime();
- double days, today, tomorrow;
- int cnt;
- char *strerror();
-
- if (gettimeofday(&tp,&tzp)) {
- (void)fprintf(stderr, "pom: %s\n", strerror(errno));
- exit(1);
- }
- GMT = gmtime(&tp.tv_sec);
- 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) ? 366 : 365;
- today = potm(days) + .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");
- else {
- (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);
- }
- }
- }
-
- /*
- * potm --
- * return phase of the moon
- */
- double
- potm(days)
- double days;
- {
- double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime;
- double A4, lprime, V, ldprime, D, Nm;
-
- N = 360 * days / 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 * days + lzero; /* sec 61 #4 */
- adj360(&l);
- Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */
- adj360(&Mm);
- Nm = Nzero - (0.0529539 * days); /* 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
- */
- double
- dtor(deg)
- double deg;
- {
- return(deg * PI / 180);
- }
-
- /*
- * adj360 --
- * adjust value so 0 <= deg <= 360
- */
- double
- adj360(deg)
- double *deg;
- {
- for (;;)
- if (*deg < 0)
- *deg += 360;
- else if (*deg > 360)
- *deg -= 360;
- else
- break;
- }
-