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Annotation of 43BSDReno/games/pom/pom.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1989 The Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * This code is derived from software posted to USENET.
        !             6:  *
        !             7:  * Redistribution and use in source and binary forms are permitted
        !             8:  * provided that: (1) source distributions retain this entire copyright
        !             9:  * notice and comment, and (2) distributions including binaries display
        !            10:  * the following acknowledgement:  ``This product includes software
        !            11:  * developed by the University of California, Berkeley and its contributors''
        !            12:  * in the documentation or other materials provided with the distribution
        !            13:  * and in all advertising materials mentioning features or use of this
        !            14:  * software. Neither the name of the University nor the names of its
        !            15:  * contributors may be used to endorse or promote products derived
        !            16:  * from this software without specific prior written permission.
        !            17:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            18:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            19:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            20:  */
        !            21: 
        !            22: #ifndef lint
        !            23: char copyright[] =
        !            24: "@(#) Copyright (c) 1989 The Regents of the University of California.\n\
        !            25:  All rights reserved.\n";
        !            26: #endif /* not lint */
        !            27: 
        !            28: #ifndef lint
        !            29: static char sccsid[] = "@(#)pom.c      5.2 (Berkeley) 6/1/90";
        !            30: #endif /* not lint */
        !            31: 
        !            32: /*
        !            33:  * Phase of the Moon.  Calculates the current phase of the moon.
        !            34:  * Based on routines from `Practical Astronomy with Your Calculator',
        !            35:  * by Duffett-Smith.  Comments give the section from the book that
        !            36:  * particular piece of code was adapted from.
        !            37:  *
        !            38:  * -- Keith E. Brandt  VIII 1984
        !            39:  *
        !            40:  */
        !            41: 
        !            42: #include <sys/time.h>
        !            43: #include <stdio.h>
        !            44: #include <tzfile.h>
        !            45: #include <math.h>
        !            46: 
        !            47: #define        PI        3.141592654
        !            48: #define        EPOCH     85
        !            49: #define        EPSILONg  279.611371    /* solar ecliptic long at EPOCH */
        !            50: #define        RHOg      282.680403    /* solar ecliptic long of perigee at EPOCH */
        !            51: #define        ECCEN     0.01671542    /* solar orbit eccentricity */
        !            52: #define        lzero     18.251907     /* lunar mean long at EPOCH */
        !            53: #define        Pzero     192.917585    /* lunar mean long of perigee at EPOCH */
        !            54: #define        Nzero     55.204723     /* lunar mean long of node at EPOCH */
        !            55: 
        !            56: main()
        !            57: {
        !            58:        extern int errno;
        !            59:        struct timeval tp;
        !            60:        struct timezone tzp;
        !            61:        struct tm *GMT, *gmtime();
        !            62:        double days, today, tomorrow, dtor(), adj360(), potm();
        !            63:        int cnt;
        !            64:        char *strerror();
        !            65: 
        !            66:        if (gettimeofday(&tp,&tzp)) {
        !            67:                (void)fprintf(stderr, "pom: %s\n", strerror(errno));
        !            68:                exit(1);
        !            69:        }
        !            70:        GMT = gmtime(&tp.tv_sec);
        !            71:        days = (GMT->tm_yday + 1) + ((GMT->tm_hour +
        !            72:            (GMT->tm_min / 60.0) + (GMT->tm_sec / 3600.0)) / 24.0);
        !            73:        for (cnt = EPOCH; cnt < GMT->tm_year; ++cnt)
        !            74:                days += isleap(cnt) ? 366 : 365;
        !            75:        today = potm(days) + .5;
        !            76:        (void)printf("The Moon is ");
        !            77:        if ((int)today == 100)
        !            78:                (void)printf("Full\n");
        !            79:        else if (!(int)today)
        !            80:                (void)printf("New\n");
        !            81:        else {
        !            82:                tomorrow = potm(days + 1);
        !            83:                if ((int)today == 50)
        !            84:                        (void)printf("%s\n", tomorrow > today ?
        !            85:                            "at the First Quarter" : "at the Last Quarter");
        !            86:                else {
        !            87:                        (void)printf("%s ", tomorrow > today ?
        !            88:                            "Waxing" : "Waning");
        !            89:                        if (today > 50)
        !            90:                                (void)printf("Gibbous (%1.0f%% of Full)\n",
        !            91:                                    today);
        !            92:                        else if (today < 50)
        !            93:                                (void)printf("Crescent (%1.0f%% of Full)\n",
        !            94:                                    today);
        !            95:                }
        !            96:        }
        !            97: }
        !            98: 
        !            99: /*
        !           100:  * potm --
        !           101:  *     return phase of the moon
        !           102:  */
        !           103: double
        !           104: potm(days)
        !           105:        double days;
        !           106: {
        !           107:        double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime;
        !           108:        double A4, lprime, V, ldprime, D, Nm;
        !           109: 
        !           110:        N = 360 * days / 365.2422;                              /* sec 42 #3 */
        !           111:        adj360(&N);
        !           112:        Msol = N + EPSILONg - RHOg;                             /* sec 42 #4 */
        !           113:        adj360(&Msol);
        !           114:        Ec = 360 / PI * ECCEN * sin(dtor(Msol));                /* sec 42 #5 */
        !           115:        LambdaSol = N + Ec + EPSILONg;                          /* sec 42 #6 */
        !           116:        adj360(&LambdaSol);
        !           117:        l = 13.1763966 * days + lzero;                          /* sec 61 #4 */
        !           118:        adj360(&l);
        !           119:        Mm = l - (0.1114041 * days) - Pzero;                    /* sec 61 #5 */
        !           120:        adj360(&Mm);
        !           121:        Nm = Nzero - (0.0529539 * days);                        /* sec 61 #6 */
        !           122:        adj360(&Nm);
        !           123:        Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm));        /* sec 61 #7 */
        !           124:        Ac = 0.1858 * sin(dtor(Msol));                          /* sec 61 #8 */
        !           125:        A3 = 0.37 * sin(dtor(Msol));
        !           126:        Mmprime = Mm + Ev - Ac - A3;                            /* sec 61 #9 */
        !           127:        Ec = 6.2886 * sin(dtor(Mmprime));                       /* sec 61 #10 */
        !           128:        A4 = 0.214 * sin(dtor(2 * Mmprime));                    /* sec 61 #11 */
        !           129:        lprime = l + Ev + Ec - Ac + A4;                         /* sec 61 #12 */
        !           130:        V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol)));       /* sec 61 #13 */
        !           131:        ldprime = lprime + V;                                   /* sec 61 #14 */
        !           132:        D = ldprime - LambdaSol;                                /* sec 63 #2 */
        !           133:        return(50 * (1 - cos(dtor(D))));                        /* sec 63 #3 */
        !           134: }
        !           135: 
        !           136: /*
        !           137:  * dtor --
        !           138:  *     convert degrees to radians
        !           139:  */
        !           140: double
        !           141: dtor(deg)
        !           142:        double deg;
        !           143: {
        !           144:        return(deg * PI / 180);
        !           145: }
        !           146: 
        !           147: /*
        !           148:  * adj360 --
        !           149:  *     adjust value so 0 <= deg <= 360
        !           150:  */
        !           151: double
        !           152: adj360(deg)
        !           153:        double *deg;
        !           154: {
        !           155:        for (;;)
        !           156:                if (*deg < 0)
        !           157:                        *deg += 360;
        !           158:                else if (*deg > 360)
        !           159:                        *deg -= 360;
        !           160:                else
        !           161:                        break;
        !           162: }

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