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449 lines
12 KiB
C
449 lines
12 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2009-2010 Edwin Groothuis <edwin@FreeBSD.org>.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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#include <sys/cdefs.h>
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/*
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* This code is created to match the formulas available at:
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* Formula and examples obtained from "How to Calculate alt/az: SAAO" at
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* http://old.saao.ac.za/public-info/sun-moon-stars/sun-index/how-to-calculate-altaz/
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <limits.h>
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#include <math.h>
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#include <string.h>
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#include <time.h>
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#include "calendar.h"
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#define D2R(m) ((m) / 180 * M_PI)
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#define R2D(m) ((m) * 180 / M_PI)
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#define SIN(x) (sin(D2R(x)))
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#define COS(x) (cos(D2R(x)))
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#define TAN(x) (tan(D2R(x)))
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#define ASIN(x) (R2D(asin(x)))
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#define ATAN(x) (R2D(atan(x)))
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#ifdef NOTDEF
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static void
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comp(char *s, double v, double c)
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{
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printf("%-*s %*g %*g %*g\n", 15, s, 15, v, 15, c, 15, v - c);
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}
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int expY;
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double expZJ = 30.5;
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double expUTHM = 8.5;
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double expD = 34743.854;
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double expT = 0.9512349;
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double expL = 324.885;
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double expM = 42.029;
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double expepsilon = 23.4396;
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double explambda = 326.186;
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double expalpha = 328.428;
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double expDEC = -12.789;
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double expeastlongitude = 17.10;
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double explatitude = -22.57;
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double expHA = -37.673;
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double expALT = 49.822;
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double expAZ = 67.49;
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#endif
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static double
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fixup(double *d)
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{
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if (*d < 0) {
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while (*d < 0)
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*d += 360;
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} else {
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while (*d > 360)
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*d -= 360;
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}
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return (*d);
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}
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static double ZJtable[] = {
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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 };
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static void
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sunpos(int inYY, int inMM, int inDD, double UTCOFFSET, int inHOUR, int inMIN,
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int inSEC, double eastlongitude, double latitude, double *L, double *DEC)
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{
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int Y;
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double ZJ, D, T, M, epsilon, lambda, alpha, HA, UTHM;
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ZJ = ZJtable[inMM];
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if (inMM <= 2 && isleap(inYY))
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ZJ -= 1.0;
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UTHM = inHOUR + inMIN / FMINSPERHOUR + inSEC / FSECSPERHOUR - UTCOFFSET;
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Y = inYY - 1900; /* 1 */
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D = floor(365.25 * Y) + ZJ + inDD + UTHM / FHOURSPERDAY; /* 3 */
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T = D / 36525.0; /* 4 */
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*L = 279.697 + 36000.769 * T; /* 5 */
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fixup(L);
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M = 358.476 + 35999.050 * T; /* 6 */
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fixup(&M);
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epsilon = 23.452 - 0.013 * T; /* 7 */
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fixup(&epsilon);
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lambda = *L + (1.919 - 0.005 * T) * SIN(M) + 0.020 * SIN(2 * M);/* 8 */
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fixup(&lambda);
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alpha = ATAN(TAN(lambda) * COS(epsilon)); /* 9 */
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/* Alpha should be in the same quadrant as lamba */
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{
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int lssign = sin(D2R(lambda)) < 0 ? -1 : 1;
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int lcsign = cos(D2R(lambda)) < 0 ? -1 : 1;
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while (((sin(D2R(alpha)) < 0) ? -1 : 1) != lssign
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|| ((cos(D2R(alpha)) < 0) ? -1 : 1) != lcsign)
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alpha += 90.0;
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}
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fixup(&alpha);
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*DEC = ASIN(SIN(lambda) * SIN(epsilon)); /* 10 */
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fixup(DEC);
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fixup(&eastlongitude);
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HA = *L - alpha + 180 + 15 * UTHM + eastlongitude; /* 12 */
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fixup(&HA);
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fixup(&latitude);
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#ifdef NOTDEF
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printf("%02d/%02d %02d:%02d:%02d l:%g d:%g h:%g\n",
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inMM, inDD, inHOUR, inMIN, inSEC, latitude, *DEC, HA);
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#endif
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return;
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/*
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* The following calculations are not used, so to save time
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* they are not calculated.
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*/
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#ifdef NOTDEF
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*ALT = ASIN(SIN(latitude) * SIN(*DEC) +
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COS(latitude) * COS(*DEC) * COS(HA)); /* 13 */
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fixup(ALT);
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*AZ = ATAN(SIN(HA) /
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(COS(HA) * SIN(latitude) - TAN(*DEC) * COS(latitude))); /* 14 */
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if (*ALT > 180)
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*ALT -= 360;
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if (*ALT < -180)
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*ALT += 360;
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printf("a:%g a:%g\n", *ALT, *AZ);
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#endif
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#ifdef NOTDEF
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printf("Y:\t\t\t %d\t\t %d\t\t %d\n", Y, expY, Y - expY);
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comp("ZJ", ZJ, expZJ);
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comp("UTHM", UTHM, expUTHM);
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comp("D", D, expD);
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comp("T", T, expT);
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comp("L", L, fixup(&expL));
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comp("M", M, fixup(&expM));
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comp("epsilon", epsilon, fixup(&expepsilon));
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comp("lambda", lambda, fixup(&explambda));
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comp("alpha", alpha, fixup(&expalpha));
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comp("DEC", DEC, fixup(&expDEC));
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comp("eastlongitude", eastlongitude, fixup(&expeastlongitude));
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comp("latitude", latitude, fixup(&explatitude));
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comp("HA", HA, fixup(&expHA));
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comp("ALT", ALT, fixup(&expALT));
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comp("AZ", AZ, fixup(&expAZ));
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#endif
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}
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#define SIGN(a) (((a) > 180) ? -1 : 1)
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#define ANGLE(a, b) (((a) < (b)) ? 1 : -1)
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#define SHOUR(s) ((s) / 3600)
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#define SMIN(s) (((s) % 3600) / 60)
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#define SSEC(s) ((s) % 60)
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#define HOUR(h) ((h) / 4)
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#define MIN(h) (15 * ((h) % 4))
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#define SEC(h) 0
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#define DEBUG1(y, m, d, hh, mm, pdec, dec) \
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printf("%4d-%02d-%02d %02d:%02d:00 - %7.7g -> %7.7g\n", \
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y, m, d, hh, mm, pdec, dec)
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#define DEBUG2(y, m, d, hh, mm, pdec, dec, pang, ang) \
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printf("%4d-%02d-%02d %02d:%02d:00 - %7.7g -> %7.7g - %d -> %d\n", \
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y, m, d, hh, mm, pdec, dec, pang, ang)
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void
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equinoxsolstice(int year, double UTCoffset, int *equinoxdays, int *solsticedays)
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{
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double fe[2], fs[2];
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fequinoxsolstice(year, UTCoffset, fe, fs);
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equinoxdays[0] = round(fe[0]);
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equinoxdays[1] = round(fe[1]);
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solsticedays[0] = round(fs[0]);
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solsticedays[1] = round(fs[1]);
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}
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void
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fequinoxsolstice(int year, double UTCoffset, double *equinoxdays, double *solsticedays)
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{
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double dec, prevdec, L;
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int h, d, prevangle, angle;
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int found = 0;
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double decleft, decright, decmiddle;
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int dial, s;
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int *cumdays;
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cumdays = cumdaytab[isleap(year)];
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/*
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* Find the first equinox, somewhere in March:
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* It happens when the returned value "dec" goes from
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* [350 ... 360> -> [0 ... 10]
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*/
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for (d = 18; d < 31; d++) {
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/* printf("Comparing day %d to %d.\n", d, d+1); */
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sunpos(year, 3, d, UTCoffset, 0, 0, 0, 0.0, 0.0, &L, &decleft);
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sunpos(year, 3, d + 1, UTCoffset, 0, 0, 0, 0.0, 0.0,
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&L, &decright);
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/* printf("Found %g and %g.\n", decleft, decright); */
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if (SIGN(decleft) == SIGN(decright))
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continue;
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dial = SECSPERDAY;
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s = SECSPERDAY / 2;
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while (s > 0) {
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/* printf("Obtaining %d (%02d:%02d)\n",
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dial, SHOUR(dial), SMIN(dial)); */
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sunpos(year, 3, d, UTCoffset,
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SHOUR(dial), SMIN(dial), SSEC(dial),
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0.0, 0.0, &L, &decmiddle);
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/* printf("Found %g\n", decmiddle); */
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if (SIGN(decleft) == SIGN(decmiddle)) {
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decleft = decmiddle;
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dial += s;
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} else {
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decright = decmiddle;
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dial -= s;
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}
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/*
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printf("New boundaries: %g - %g\n", decleft, decright);
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*/
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s /= 2;
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}
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equinoxdays[0] = 1 + cumdays[3] + d + (dial / FSECSPERDAY);
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break;
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}
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/* Find the second equinox, somewhere in September:
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* It happens when the returned value "dec" goes from
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* [10 ... 0] -> <360 ... 350]
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*/
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for (d = 18; d < 31; d++) {
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/* printf("Comparing day %d to %d.\n", d, d+1); */
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sunpos(year, 9, d, UTCoffset, 0, 0, 0, 0.0, 0.0, &L, &decleft);
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sunpos(year, 9, d + 1, UTCoffset, 0, 0, 0, 0.0, 0.0,
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&L, &decright);
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/* printf("Found %g and %g.\n", decleft, decright); */
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if (SIGN(decleft) == SIGN(decright))
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continue;
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dial = SECSPERDAY;
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s = SECSPERDAY / 2;
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while (s > 0) {
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/* printf("Obtaining %d (%02d:%02d)\n",
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dial, SHOUR(dial), SMIN(dial)); */
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sunpos(year, 9, d, UTCoffset,
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SHOUR(dial), SMIN(dial), SSEC(dial),
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0.0, 0.0, &L, &decmiddle);
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/* printf("Found %g\n", decmiddle); */
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if (SIGN(decleft) == SIGN(decmiddle)) {
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decleft = decmiddle;
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dial += s;
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} else {
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decright = decmiddle;
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dial -= s;
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}
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/*
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printf("New boundaries: %g - %g\n", decleft, decright);
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*/
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s /= 2;
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}
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equinoxdays[1] = 1 + cumdays[9] + d + (dial / FSECSPERDAY);
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break;
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}
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/*
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* Find the first solstice, somewhere in June:
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* It happens when the returned value "dec" peaks
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* [40 ... 45] -> [45 ... 40]
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*/
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found = 0;
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prevdec = 0;
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prevangle = 1;
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for (d = 18; d < 31; d++) {
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for (h = 0; h < 4 * HOURSPERDAY; h++) {
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sunpos(year, 6, d, UTCoffset, HOUR(h), MIN(h), SEC(h),
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0.0, 0.0, &L, &dec);
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angle = ANGLE(prevdec, dec);
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if (prevangle != angle) {
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#ifdef NOTDEF
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DEBUG2(year, 6, d, HOUR(h), MIN(h),
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prevdec, dec, prevangle, angle);
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#endif
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solsticedays[0] = 1 + cumdays[6] + d +
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((h / 4.0) / 24.0);
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found = 1;
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break;
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}
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prevdec = dec;
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prevangle = angle;
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}
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if (found)
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break;
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}
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/*
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* Find the second solstice, somewhere in December:
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* It happens when the returned value "dec" peaks
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* [315 ... 310] -> [310 ... 315]
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*/
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found = 0;
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prevdec = 360;
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prevangle = -1;
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for (d = 18; d < 31; d++) {
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for (h = 0; h < 4 * HOURSPERDAY; h++) {
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sunpos(year, 12, d, UTCoffset, HOUR(h), MIN(h), SEC(h),
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0.0, 0.0, &L, &dec);
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angle = ANGLE(prevdec, dec);
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if (prevangle != angle) {
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#ifdef NOTDEF
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DEBUG2(year, 12, d, HOUR(h), MIN(h),
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prevdec, dec, prevangle, angle);
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#endif
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solsticedays[1] = 1 + cumdays[12] + d +
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((h / 4.0) / 24.0);
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found = 1;
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break;
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}
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prevdec = dec;
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prevangle = angle;
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}
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if (found)
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break;
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}
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return;
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}
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int
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calculatesunlongitude30(int year, int degreeGMToffset, int *ichinesemonths)
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{
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int m, d, h;
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double dec;
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double curL, prevL;
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int *pichinesemonths, *monthdays, *cumdays, i;
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int firstmonth330 = -1;
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cumdays = cumdaytab[isleap(year)];
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monthdays = monthdaytab[isleap(year)];
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pichinesemonths = ichinesemonths;
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h = 0;
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sunpos(year - 1, 12, 31,
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-24 * (degreeGMToffset / 360.0),
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HOUR(h), MIN(h), SEC(h), 0.0, 0.0, &prevL, &dec);
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for (m = 1; m <= 12; m++) {
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for (d = 1; d <= monthdays[m]; d++) {
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for (h = 0; h < 4 * HOURSPERDAY; h++) {
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sunpos(year, m, d,
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-24 * (degreeGMToffset / 360.0),
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HOUR(h), MIN(h), SEC(h),
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0.0, 0.0, &curL, &dec);
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if (curL < 180 && prevL > 180) {
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*pichinesemonths = cumdays[m] + d;
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#ifdef DEBUG
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printf("%04d-%02d-%02d %02d:%02d - %d %g\n",
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year, m, d, HOUR(h), MIN(h), *pichinesemonths, curL);
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#endif
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pichinesemonths++;
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} else {
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for (i = 0; i <= 360; i += 30)
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if (curL > i && prevL < i) {
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*pichinesemonths =
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cumdays[m] + d;
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#ifdef DEBUG
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printf("%04d-%02d-%02d %02d:%02d - %d %g\n",
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year, m, d, HOUR(h), MIN(h), *pichinesemonths, curL);
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#endif
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if (i == 330)
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firstmonth330 = *pichinesemonths;
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pichinesemonths++;
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}
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}
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prevL = curL;
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}
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}
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}
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*pichinesemonths = -1;
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return (firstmonth330);
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}
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#ifdef NOTDEF
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int
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main(int argc, char **argv)
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{
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/*
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year Mar June Sept Dec
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day time day time day time day time
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2004 20 06:49 21 00:57 22 16:30 21 12:42
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2005 20 12:33 21 06:46 22 22:23 21 18:35
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2006 20 18:26 21 12:26 23 04:03 22 00:22
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2007 21 00:07 21 18:06 23 09:51 22 06:08
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2008 20 05:48 20 23:59 22 15:44 21 12:04
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2009 20 11:44 21 05:45 22 21:18 21 17:47
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2010 20 17:32 21 11:28 23 03:09 21 23:38
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2011 20 23:21 21 17:16 23 09:04 22 05:30
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2012 20 05:14 20 23:09 22 14:49 21 11:11
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2013 20 11:02 21 05:04 22 20:44 21 17:11
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2014 20 16:57 21 10:51 23 02:29 21 23:03
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2015 20 22:45 21 16:38 23 08:20 22 04:48
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2016 20 04:30 20 22:34 22 14:21 21 10:44
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2017 20 10:28 21 04:24 22 20:02 21 16:28
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*/
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int eq[2], sol[2];
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equinoxsolstice(strtol(argv[1], NULL, 10), 0.0, eq, sol);
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printf("%d - %d - %d - %d\n", eq[0], sol[0], eq[1], sol[1]);
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return(0);
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}
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#endif
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