33  * Phase of the Moon.  Calculates the current phase of the moon.
35  * by Duffett-Smith.  Comments give the section from the book that
38  * -- Keith E. Brandt  VIII 1984
67 static void	adj360(double *);
68 static double	dtor(double);
69 static double	potm(double);
77 	double days, today, tomorrow;  in main()
89 	while ((ch = getopt(argc, argv, "d:pt:")) != -1)  in main()
104         argc -= optind;  in main()
113 		/* Save today in case -d isn't specified */  in main()
117 			tmd.tm_year = strtol(odate, NULL, 10) - 1900;  in main()
118 			tmd.tm_mon = strtol(odate + 5, NULL, 10) - 1;  in main()
124 			tmd.tm_isdst = -1;  in main()
130 			tmd.tm_isdst = -1;  in main()
171  * potm --
172  *	return phase of the moon
174 static double
175 potm(double days)  in potm()
177 	double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime;  in potm()
178 	double A4, lprime, V, ldprime, D, Nm;  in potm()
182 	Msol = N + EPSILONg - RHOg;				/* sec 42 #4 */  in potm()
189 	Mm = l - (0.1114041 * days) - Pzero;			/* sec 61 #5 */  in potm()
191 	Nm = Nzero - (0.0529539 * days);			/* sec 61 #6 */  in potm()
193 	Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm));	/* sec 61 #7 */  in potm()
196 	Mmprime = Mm + Ev - Ac - A3;				/* sec 61 #9 */  in potm()
199 	lprime = l + Ev + Ec - Ac + A4;				/* sec 61 #12 */  in potm()
200 	V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol)));	/* sec 61 #13 */  in potm()
202 	D = ldprime - LambdaSol;				/* sec 63 #2 */  in potm()
203 	return(50 * (1 - cos(dtor(D))));			/* sec 63 #3 */  in potm()
207  * dtor --
210 static double
211 dtor(double deg)  in dtor()
218  * adj360 --
222 adj360(double *deg)  in adj360()
229 			*deg -= 360;  in adj360()
238 	fprintf(stderr, "Usage: %s [-p] [-d yyyy.mm.dd] [-t hh:mm:ss]\n",  in usage()