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| Current File : //usr/src/usr.bin/calendar/pom.c |
/*
* 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.
* 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.
*/
#if 0
#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1989, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static const char sccsid[] = "@(#)pom.c 8.1 (Berkeley) 5/31/93";
#endif /* not lint */
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/usr.bin/calendar/pom.c 223923 2011-07-11 05:40:46Z delphij $");
/*
* 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 <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <sysexits.h>
#include <time.h>
#include <unistd.h>
#include "calendar.h"
#ifndef PI
#define PI 3.14159265358979323846
#endif
#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 isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
static void adj360(double *);
static double dtor(double);
static double potm(double onday);
static double potm_minute(double onday, int olddir);
void
pom(int year, double utcoffset, int *fms, int *nms)
{
double ffms[MAXMOONS];
double fnms[MAXMOONS];
int i, j;
fpom(year, utcoffset, ffms, fnms);
j = 0;
for (i = 0; ffms[i] != 0; i++)
fms[j++] = round(ffms[i]);
fms[i] = -1;
for (i = 0; fnms[i] != 0; i++)
nms[i] = round(fnms[i]);
nms[i] = -1;
}
void
fpom(int year, double utcoffset, double *ffms, double *fnms)
{
time_t tt;
struct tm GMT, tmd_today, tmd_tomorrow;
double days_today, days_tomorrow, today, tomorrow;
int cnt, d;
int yeardays;
int olddir, newdir;
double *pfnms, *pffms, t;
pfnms = fnms;
pffms = ffms;
/*
* We take the phase of the moon one second before and one second
* after midnight.
*/
memset(&tmd_today, 0, sizeof(tmd_today));
tmd_today.tm_year = year - 1900;
tmd_today.tm_mon = 0;
tmd_today.tm_mday = -1; /* 31 December */
tmd_today.tm_hour = 23;
tmd_today.tm_min = 59;
tmd_today.tm_sec = 59;
memset(&tmd_tomorrow, 0, sizeof(tmd_tomorrow));
tmd_tomorrow.tm_year = year - 1900;
tmd_tomorrow.tm_mon = 0;
tmd_tomorrow.tm_mday = 0; /* 01 January */
tmd_tomorrow.tm_hour = 0;
tmd_tomorrow.tm_min = 0;
tmd_tomorrow.tm_sec = 1;
tt = mktime(&tmd_today);
gmtime_r(&tt, &GMT);
yeardays = 0;
for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt)
yeardays += isleap(1900 + cnt) ? DAYSPERLEAPYEAR : DAYSPERYEAR;
days_today = (GMT.tm_yday + 1) + ((GMT.tm_hour +
(GMT.tm_min / FSECSPERMINUTE) + (GMT.tm_sec / FSECSPERHOUR)) /
FHOURSPERDAY);
days_today += yeardays;
tt = mktime(&tmd_tomorrow);
gmtime_r(&tt, &GMT);
yeardays = 0;
for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt)
yeardays += isleap(1900 + cnt) ? DAYSPERLEAPYEAR : DAYSPERYEAR;
days_tomorrow = (GMT.tm_yday + 1) + ((GMT.tm_hour +
(GMT.tm_min / FSECSPERMINUTE) + (GMT.tm_sec / FSECSPERHOUR)) /
FHOURSPERDAY);
days_tomorrow += yeardays;
today = potm(days_today); /* 30 December 23:59:59 */
tomorrow = potm(days_tomorrow); /* 31 December 00:00:01 */
olddir = today > tomorrow ? -1 : +1;
yeardays = 1 + (isleap(year) ? DAYSPERLEAPYEAR : DAYSPERYEAR); /* reuse */
for (d = 0; d <= yeardays; d++) {
today = potm(days_today);
tomorrow = potm(days_tomorrow);
newdir = today > tomorrow ? -1 : +1;
if (olddir != newdir) {
t = potm_minute(days_today - 1, olddir) +
utcoffset / FHOURSPERDAY;
if (olddir == -1 && newdir == +1) {
*pfnms = d - 1 + t;
pfnms++;
} else if (olddir == +1 && newdir == -1) {
*pffms = d - 1 + t;
pffms++;
}
}
olddir = newdir;
days_today++;
days_tomorrow++;
}
*pffms = -1;
*pfnms = -1;
}
static double
potm_minute(double onday, int olddir) {
double period = FSECSPERDAY / 2.0;
double p1, p2;
double before, after;
int newdir;
// printf("---> days:%g olddir:%d\n", days, olddir);
p1 = onday + (period / SECSPERDAY);
period /= 2;
while (period > 30) { /* half a minute */
// printf("period:%g - p1:%g - ", period, p1);
p2 = p1 + (2.0 / SECSPERDAY);
before = potm(p1);
after = potm(p2);
// printf("before:%10.10g - after:%10.10g\n", before, after);
newdir = before < after ? -1 : +1;
if (olddir != newdir)
p1 += (period / SECSPERDAY);
else
p1 -= (period / SECSPERDAY);
period /= 2;
// printf("newdir:%d - p1:%10.10f - period:%g\n",
// newdir, p1, period);
}
p1 -= floor(p1);
//exit(0);
return (p1);
}
/*
* potm --
* return phase of the moon, as a percentage [0 ... 100]
*/
static double
potm(double onday)
{
double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime;
double A4, lprime, V, ldprime, D, Nm;
N = 360 * onday / 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 * onday + lzero; /* sec 61 #4 */
adj360(&l);
Mm = l - (0.1114041 * onday) - Pzero; /* sec 61 #5 */
adj360(&Mm);
Nm = Nzero - (0.0529539 * onday); /* 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
*/
static double
dtor(double deg)
{
return(deg * PI / 180);
}
/*
* adj360 --
* adjust value so 0 <= deg <= 360
*/
static void
adj360(double *deg)
{
for (;;)
if (*deg < 0)
*deg += 360;
else if (*deg > 360)
*deg -= 360;
else
break;
}