Use formulae from newer edition of Duffett-Smith's book (and acknowledge in

	man page)
Allow command-line selection of dates other than now
Use M_PI
Fix bug occurring just before a new or full moon.

2 files changed, 164 insertions, 47 deletions

diff --git a/games/pom/pom.6 b/games/pom/pom.6
index 3529a465bde..69140130819 100644
--- a/games/pom/pom.6
+++ b/games/pom/pom.6
@@ -1,4 +1,4 @@
-.\"	$NetBSD: pom.6,v 1.4 1995/03/23 08:35:35 cgd Exp $
+.\"	$OpenBSD: pom.6,v 1.2 1998/09/06 12:29:23 pjanzen Exp $
 .\"
 .\" Copyright (c) 1989, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -40,10 +40,28 @@
 .Nm pom 
 .Nd display the phase of the moon
 .Sh SYNOPSIS
-.Nm pom
+.Nm
+.Op [[[[[cc]yy]mm]dd]HH]
 .Sh DESCRIPTION
 The
-.Nm pom
+.Nm
 utility displays the current phase of the moon.
 Useful for selecting software completion target dates and predicting 
 managerial behavior.
+.Pp
+.Bl -tag -width [[[[[cc]yy]mm]dd]HH]
+.It Ar [[[[[cc]yy]mm]dd]HH]
+Display the phase of the moon for a given time.  The format is similar to
+the canonical representation used by
+.Xr date 1 .
+.El
+.Sh SEE ALSO
+.Xr date 1
+.Sh BUGS
+Times must be within range of the
+.Ux
+epoch.
+.Sh ACKNOWLEDGEMENTS
+This program is based on routines from 
+.%B Practical Astronomy with Your Calculator, Third Edition
+by Peter Duffett-Smith.
diff --git a/games/pom/pom.c b/games/pom/pom.c
index 50201e4cf2c..d05529306c8 100644
--- a/games/pom/pom.c
+++ b/games/pom/pom.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pom.c,v 1.5 1998/07/26 06:27:39 pjanzen Exp $	*/
+/*	$OpenBSD: pom.c,v 1.6 1998/09/06 12:29:25 pjanzen Exp $	*/
 /*    $NetBSD: pom.c,v 1.6 1996/02/06 22:47:29 jtc Exp $      */
 
 /*
@@ -46,7 +46,7 @@ static char copyright[] =
 #if 0
 static char sccsid[] = "@(#)pom.c	8.1 (Berkeley) 5/31/93";
 #else
-static char rcsid[] = "$NetBSD: pom.c,v 1.6 1996/02/06 22:47:29 jtc Exp $";
+static char rcsid[] = "$OpenBSD: pom.c,v 1.6 1998/09/06 12:29:25 pjanzen Exp $";
 #endif
 #endif /* not lint */
 
@@ -58,50 +58,74 @@ static char rcsid[] = "$NetBSD: pom.c,v 1.6 1996/02/06 22:47:29 jtc Exp $";
  *
  * -- 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 <string.h>
-#include <tzfile.h>
 #include <math.h>
-#include <errno.h>
+#include <err.h>
+#include <tzfile.h>
+#include <unistd.h>
+
+#ifndef M_PI
+#define	M_PI	  3.14159265358979323846
+#endif
 
-#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 */
+#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 */
 
-double dtor(), potm(), adj360();
+void	adj360 __P((double *));
+double	dtor __P((double));
+double	potm __P((double));
+time_t	parsetime __P((char *));
+void	badformat __P((void));
 
-main()
+int
+main(argc, argv)
+	int argc;
+	char *argv[];
 {
 	struct timeval tp;
 	struct timezone tzp;
-	struct tm *GMT, *gmtime();
+	struct tm *GMT;
 	time_t tmpt;
 	double days, today, tomorrow;
 	int cnt;
+	char buf[1024];
 
 	/* revoke */
 	setegid(getgid());
 	setgid(getgid());
 
-	if (gettimeofday(&tp,&tzp)) {
-		(void)fprintf(stderr, "pom: %s\n", strerror(errno));
-		exit(1);
+	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;
 	}
-	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 + 1900) ? 366 : 365;
-	today = potm(days) + .5;
+		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");
@@ -112,7 +136,11 @@ main()
 		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)
@@ -137,30 +165,30 @@ potm(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 */
+	N = 360.0 * days / 365.242191;				/* sec 46 #3 */
 	adj360(&N);
-	Msol = N + EPSILONg - RHOg;				/* sec 42 #4 */
+	Msol = N + EPSILONg - RHOg;				/* sec 46 #4 */
 	adj360(&Msol);
-	Ec = 360 / PI * ECCEN * sin(dtor(Msol));		/* sec 42 #5 */
-	LambdaSol = N + Ec + EPSILONg;				/* sec 42 #6 */
+	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 61 #4 */
+	l = 13.1763966 * days + lzero;				/* sec 65 #4 */
 	adj360(&l);
-	Mm = l - (0.1114041 * days) - Pzero;			/* sec 61 #5 */
+	Mm = l - (0.1114041 * days) - Pzero;			/* sec 65 #5 */
 	adj360(&Mm);
-	Nm = Nzero - (0.0529539 * days);			/* sec 61 #6 */
+	Nm = Nzero - (0.0529539 * days);			/* sec 65 #6 */
 	adj360(&Nm);
-	Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm));	/* sec 61 #7 */
-	Ac = 0.1858 * sin(dtor(Msol));				/* sec 61 #8 */
+	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 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 */
+	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 */
 }
 
 /*
@@ -171,22 +199,93 @@ double
 dtor(deg)
 	double deg;
 {
-	return(deg * PI / 180);
+	return(deg * M_PI / 180);
 }
 
 /*
  * adj360 --
  *	adjust value so 0 <= deg <= 360
  */
-double
+void
 adj360(deg)
 	double *deg;
 {
 	for (;;)
-		if (*deg < 0)
-			*deg += 360;
-		else if (*deg > 360)
-			*deg -= 360;
+		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(p)
+	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()
+{
+	warnx("illegal time format");
+	(void)fprintf(stderr, "usage: pom [[[[[cc]yy]mm]dd]HH]\n");
+	exit(1);
+}