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freebsd-nq/usr.bin/calendar/sunpos.c
Greg Lehey 90c72ba909 Handle some expression regressions. 
Explicitly use GNU cpp for preprocessing.
Remove explicit debugging code.
Change some variable names to be less confusing.
Improve some comments.
Improve indentation.

PR:		162211
		168785
MFC after:	2 weeks
2013-06-12 07:52:49 +00:00

449 lines
12 KiB
C
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/*-
* Copyright (c) 2009-2010 Edwin Groothuis <edwin@FreeBSD.org>.
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* This code is created to match the formulas available at:
* Formula and examples obtained from "How to Calculate alt/az: SAAO" at
* http://www.saao.ac.za/public-info/sun-moon-stars/sun-index/how-to-calculate-altaz/
*/
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <math.h>
#include <string.h>
#include <time.h>
#include "calendar.h"
#define D2R(m) ((m) / 180 * M_PI)
#define R2D(m) ((m) * 180 / M_PI)
#define SIN(x) (sin(D2R(x)))
#define COS(x) (cos(D2R(x)))
#define TAN(x) (tan(D2R(x)))
#define ASIN(x) (R2D(asin(x)))
#define ATAN(x) (R2D(atan(x)))
#ifdef NOTDEF
static void
comp(char *s, double v, double c)
{
printf("%-*s %*g %*g %*g\n", 15, s, 15, v, 15, c, 15, v - c);
}
int expY;
double expZJ = 30.5;
double expUTHM = 8.5;
double expD = 34743.854;
double expT = 0.9512349;
double expL = 324.885;
double expM = 42.029;
double expepsilon = 23.4396;
double explambda = 326.186;
double expalpha = 328.428;
double expDEC = -12.789;
double expeastlongitude = 17.10;
double explatitude = -22.57;
double expHA = -37.673;
double expALT = 49.822;
double expAZ = 67.49;
#endif
static double
fixup(double *d)
{
if (*d < 0) {
while (*d < 0)
*d += 360;
} else {
while (*d > 360)
*d -= 360;
}
return (*d);
}
static double ZJtable[] = {
0, -0.5, 30.5, 58.5, 89.5, 119.5, 150.5, 180.5, 211.5, 242.5, 272.5, 303.5, 333.5 };
static void
sunpos(int inYY, int inMM, int inDD, double UTCOFFSET, int inHOUR, int inMIN,
int inSEC, double eastlongitude, double latitude, double *L, double *DEC)
{
int Y;
double ZJ, D, T, M, epsilon, lambda, alpha, HA, UTHM;
ZJ = ZJtable[inMM];
if (inMM <= 2 && isleap(inYY))
ZJ -= 1.0;
UTHM = inHOUR + inMIN / FMINSPERHOUR + inSEC / FSECSPERHOUR - UTCOFFSET;
Y = inYY - 1900; /* 1 */
D = floor(365.25 * Y) + ZJ + inDD + UTHM / FHOURSPERDAY; /* 3 */
T = D / 36525.0; /* 4 */
*L = 279.697 + 36000.769 * T; /* 5 */
fixup(L);
M = 358.476 + 35999.050 * T; /* 6 */
fixup(&M);
epsilon = 23.452 - 0.013 * T; /* 7 */
fixup(&epsilon);
lambda = *L + (1.919 - 0.005 * T) * SIN(M) + 0.020 * SIN(2 * M);/* 8 */
fixup(&lambda);
alpha = ATAN(TAN(lambda) * COS(epsilon)); /* 9 */
/* Alpha should be in the same quadrant as lamba */
{
int lssign = sin(D2R(lambda)) < 0 ? -1 : 1;
int lcsign = cos(D2R(lambda)) < 0 ? -1 : 1;
while (((sin(D2R(alpha)) < 0) ? -1 : 1) != lssign
|| ((cos(D2R(alpha)) < 0) ? -1 : 1) != lcsign)
alpha += 90.0;
}
fixup(&alpha);
*DEC = ASIN(SIN(lambda) * SIN(epsilon)); /* 10 */
fixup(DEC);
fixup(&eastlongitude);
HA = *L - alpha + 180 + 15 * UTHM + eastlongitude; /* 12 */
fixup(&HA);
fixup(&latitude);
#ifdef NOTDEF
printf("%02d/%02d %02d:%02d:%02d l:%g d:%g h:%g\n",
inMM, inDD, inHOUR, inMIN, inSEC, latitude, *DEC, HA);
#endif
return;
/*
* The following calculations are not used, so to save time
* they are not calculated.
*/
#ifdef NOTDEF
*ALT = ASIN(SIN(latitude) * SIN(*DEC) +
COS(latitude) * COS(*DEC) * COS(HA)); /* 13 */
fixup(ALT);
*AZ = ATAN(SIN(HA) /
(COS(HA) * SIN(latitude) - TAN(*DEC) * COS(latitude))); /* 14 */
if (*ALT > 180)
*ALT -= 360;
if (*ALT < -180)
*ALT += 360;
printf("a:%g a:%g\n", *ALT, *AZ);
#endif
#ifdef NOTDEF
printf("Y:\t\t\t %d\t\t %d\t\t %d\n", Y, expY, Y - expY);
comp("ZJ", ZJ, expZJ);
comp("UTHM", UTHM, expUTHM);
comp("D", D, expD);
comp("T", T, expT);
comp("L", L, fixup(&expL));
comp("M", M, fixup(&expM));
comp("epsilon", epsilon, fixup(&expepsilon));
comp("lambda", lambda, fixup(&explambda));
comp("alpha", alpha, fixup(&expalpha));
comp("DEC", DEC, fixup(&expDEC));
comp("eastlongitude", eastlongitude, fixup(&expeastlongitude));
comp("latitude", latitude, fixup(&explatitude));
comp("HA", HA, fixup(&expHA));
comp("ALT", ALT, fixup(&expALT));
comp("AZ", AZ, fixup(&expAZ));
#endif
}
#define SIGN(a) (((a) > 180) ? -1 : 1)
#define ANGLE(a, b) (((a) < (b)) ? 1 : -1)
#define SHOUR(s) ((s) / 3600)
#define SMIN(s) (((s) % 3600) / 60)
#define SSEC(s) ((s) % 60)
#define HOUR(h) ((h) / 4)
#define MIN(h) (15 * ((h) % 4))
#define SEC(h) 0
#define DEBUG1(y, m, d, hh, mm, pdec, dec) \
printf("%4d-%02d-%02d %02d:%02d:00 - %7.7g -> %7.7g\n", \
y, m, d, hh, mm, pdec, dec)
#define DEBUG2(y, m, d, hh, mm, pdec, dec, pang, ang) \
printf("%4d-%02d-%02d %02d:%02d:00 - %7.7g -> %7.7g - %d -> %d\n", \
y, m, d, hh, mm, pdec, dec, pang, ang)
void
equinoxsolstice(int year, double UTCoffset, int *equinoxdays, int *solsticedays)
{
double fe[2], fs[2];
fequinoxsolstice(year, UTCoffset, fe, fs);
equinoxdays[0] = round(fe[0]);
equinoxdays[1] = round(fe[1]);
solsticedays[0] = round(fs[0]);
solsticedays[1] = round(fs[1]);
}
void
fequinoxsolstice(int year, double UTCoffset, double *equinoxdays, double *solsticedays)
{
double dec, prevdec, L;
int h, d, prevangle, angle;
int found = 0;
double decleft, decright, decmiddle;
int dial, s;
int *cumdays;
cumdays = cumdaytab[isleap(year)];
/*
* Find the first equinox, somewhere in March:
* It happens when the returned value "dec" goes from
* [350 ... 360> -> [0 ... 10]
*/
for (d = 18; d < 31; d++) {
/* printf("Comparing day %d to %d.\n", d, d+1); */
sunpos(year, 3, d, UTCoffset, 0, 0, 0, 0.0, 0.0, &L, &decleft);
sunpos(year, 3, d + 1, UTCoffset, 0, 0, 0, 0.0, 0.0,
&L, &decright);
/* printf("Found %g and %g.\n", decleft, decright); */
if (SIGN(decleft) == SIGN(decright))
continue;
dial = SECSPERDAY;
s = SECSPERDAY / 2;
while (s > 0) {
/* printf("Obtaining %d (%02d:%02d)\n",
dial, SHOUR(dial), SMIN(dial)); */
sunpos(year, 3, d, UTCoffset,
SHOUR(dial), SMIN(dial), SSEC(dial),
0.0, 0.0, &L, &decmiddle);
/* printf("Found %g\n", decmiddle); */
if (SIGN(decleft) == SIGN(decmiddle)) {
decleft = decmiddle;
dial += s;
} else {
decright = decmiddle;
dial -= s;
}
/*
printf("New boundaries: %g - %g\n", decleft, decright);
*/
s /= 2;
}
equinoxdays[0] = 1 + cumdays[3] + d + (dial / FSECSPERDAY);
break;
}
/* Find the second equinox, somewhere in September:
* It happens when the returned value "dec" goes from
* [10 ... 0] -> <360 ... 350]
*/
for (d = 18; d < 31; d++) {
/* printf("Comparing day %d to %d.\n", d, d+1); */
sunpos(year, 9, d, UTCoffset, 0, 0, 0, 0.0, 0.0, &L, &decleft);
sunpos(year, 9, d + 1, UTCoffset, 0, 0, 0, 0.0, 0.0,
&L, &decright);
/* printf("Found %g and %g.\n", decleft, decright); */
if (SIGN(decleft) == SIGN(decright))
continue;
dial = SECSPERDAY;
s = SECSPERDAY / 2;
while (s > 0) {
/* printf("Obtaining %d (%02d:%02d)\n",
dial, SHOUR(dial), SMIN(dial)); */
sunpos(year, 9, d, UTCoffset,
SHOUR(dial), SMIN(dial), SSEC(dial),
0.0, 0.0, &L, &decmiddle);
/* printf("Found %g\n", decmiddle); */
if (SIGN(decleft) == SIGN(decmiddle)) {
decleft = decmiddle;
dial += s;
} else {
decright = decmiddle;
dial -= s;
}
/*
printf("New boundaries: %g - %g\n", decleft, decright);
*/
s /= 2;
}
equinoxdays[1] = 1 + cumdays[9] + d + (dial / FSECSPERDAY);
break;
}
/*
* Find the first solstice, somewhere in June:
* It happens when the returned value "dec" peaks
* [40 ... 45] -> [45 ... 40]
*/
found = 0;
prevdec = 0;
prevangle = 1;
for (d = 18; d < 31; d++) {
for (h = 0; h < 4 * HOURSPERDAY; h++) {
sunpos(year, 6, d, UTCoffset, HOUR(h), MIN(h), SEC(h),
0.0, 0.0, &L, &dec);
angle = ANGLE(prevdec, dec);
if (prevangle != angle) {
#ifdef NOTDEF
DEBUG2(year, 6, d, HOUR(h), MIN(h),
prevdec, dec, prevangle, angle);
#endif
solsticedays[0] = 1 + cumdays[6] + d +
((h / 4.0) / 24.0);
found = 1;
break;
}
prevdec = dec;
prevangle = angle;
}
if (found)
break;
}
/*
* Find the second solstice, somewhere in December:
* It happens when the returned value "dec" peaks
* [315 ... 310] -> [310 ... 315]
*/
found = 0;
prevdec = 360;
prevangle = -1;
for (d = 18; d < 31; d++) {
for (h = 0; h < 4 * HOURSPERDAY; h++) {
sunpos(year, 12, d, UTCoffset, HOUR(h), MIN(h), SEC(h),
0.0, 0.0, &L, &dec);
angle = ANGLE(prevdec, dec);
if (prevangle != angle) {
#ifdef NOTDEF
DEBUG2(year, 12, d, HOUR(h), MIN(h),
prevdec, dec, prevangle, angle);
#endif
solsticedays[1] = 1 + cumdays[12] + d +
((h / 4.0) / 24.0);
found = 1;
break;
}
prevdec = dec;
prevangle = angle;
}
if (found)
break;
}
return;
}
int
calculatesunlongitude30(int year, int degreeGMToffset, int *ichinesemonths)
{
int m, d, h;
double dec;
double curL, prevL;
int *pichinesemonths, *monthdays, *cumdays, i;
int firstmonth330 = -1;
cumdays = cumdaytab[isleap(year)];
monthdays = monthdaytab[isleap(year)];
pichinesemonths = ichinesemonths;
h = 0;
sunpos(year - 1, 12, 31,
-24 * (degreeGMToffset / 360.0),
HOUR(h), MIN(h), SEC(h), 0.0, 0.0, &prevL, &dec);
for (m = 1; m <= 12; m++) {
for (d = 1; d <= monthdays[m]; d++) {
for (h = 0; h < 4 * HOURSPERDAY; h++) {
sunpos(year, m, d,
-24 * (degreeGMToffset / 360.0),
HOUR(h), MIN(h), SEC(h),
0.0, 0.0, &curL, &dec);
if (curL < 180 && prevL > 180) {
*pichinesemonths = cumdays[m] + d;
#ifdef DEBUG
printf("%04d-%02d-%02d %02d:%02d - %d %g\n",
year, m, d, HOUR(h), MIN(h), *pichinesemonths, curL);
#endif
pichinesemonths++;
} else {
for (i = 0; i <= 360; i += 30)
if (curL > i && prevL < i) {
*pichinesemonths =
cumdays[m] + d;
#ifdef DEBUG
printf("%04d-%02d-%02d %02d:%02d - %d %g\n",
year, m, d, HOUR(h), MIN(h), *pichinesemonths, curL);
#endif
if (i == 330)
firstmonth330 = *pichinesemonths;
pichinesemonths++;
}
}
prevL = curL;
}
}
}
*pichinesemonths = -1;
return (firstmonth330);
}
#ifdef NOTDEF
int
main(int argc, char **argv)
{
/*
year Mar June Sept Dec
day time day time day time day time
2004 20 06:49 21 00:57 22 16:30 21 12:42
2005 20 12:33 21 06:46 22 22:23 21 18:35
2006 20 18:26 21 12:26 23 04:03 22 00:22
2007 21 00:07 21 18:06 23 09:51 22 06:08
2008 20 05:48 20 23:59 22 15:44 21 12:04
2009 20 11:44 21 05:45 22 21:18 21 17:47
2010 20 17:32 21 11:28 23 03:09 21 23:38
2011 20 23:21 21 17:16 23 09:04 22 05:30
2012 20 05:14 20 23:09 22 14:49 21 11:11
2013 20 11:02 21 05:04 22 20:44 21 17:11
2014 20 16:57 21 10:51 23 02:29 21 23:03
2015 20 22:45 21 16:38 23 08:20 22 04:48
2016 20 04:30 20 22:34 22 14:21 21 10:44
2017 20 10:28 21 04:24 22 20:02 21 16:28
*/
int eq[2], sol[2];
equinoxsolstice(strtol(argv[1], NULL, 10), 0.0, eq, sol);
printf("%d - %d - %d - %d\n", eq[0], sol[0], eq[1], sol[1]);
return(0);
}
#endif
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