1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
/* solseqn.cpp: computes date/times of solstices and equinoxes
Copyright (C) 2010, Project Pluto
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA. */
/* Some test code I wrote a while back to compute dates/times for
solstices and equinoxes. I don't actually use it anywhere. You
can disregard it freely. */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "watdefs.h"
#include "afuncs.h"
#include "lunar.h"
#include "date.h"
#define PI 3.1415926535897932384626433832795028841971693993751058209749445923
double get_solstice_equinox_date( double jd); /* solseqn.cpp */
static double daily_variation( const double t_cen)
{
double rval = 3548.193;
int i;
static const double constants[34] = {
7.311, 333.4515, 359993.7286, /* tau */
.305, 330.9814, 719987.4571, /* tau */
.010, 328.5170, 1079981.1857, /* tau */
118.568, 87.5287, 359993.7286,
2.476, 85.0561, 719987.4571,
1.376, 27.8502, 4452671.1152,
.119, 73.1375, 450368.8564,
.114, 337.2264, 329644.6718,
.086, 222.5400, 659289.3436,
.078, 162.8136, 9224659.7915,
.054, 82.5823, 1079981.1857,
0. };
for( i = 0; constants[i] != 0.; i += 3)
{
const double arg = constants[i + 1] + constants[i + 2] * t_cen / 10.;
double term = sin( arg * PI / 180.);
if( i < 9)
term *= t_cen / 10.;
rval += constants[i] * term;
}
return( rval);
}
double get_solstice_equinox_date( double jd)
{
double err = 1.;
while( fabs( err) > .000001)
{
const double t_c = (jd - 2451545.) / 36525.;
double lon, ovals[3], d_lon;
if( calc_big_vsop_loc( NULL, 3, ovals, t_c, 0.))
return( 0.); /* failed to find the 'big_vsop.bin' file */
lon = ovals[0] - .09033 * (PI / 180.) / 3600.;
nutation( t_c, &d_lon, NULL);
lon += d_lon * (PI / 180.) / 3600.;
/* now include aberration: */
lon -= .005775518 * ovals[2] *
daily_variation( t_c) * (PI / 180.) / 3600.;
/* now convert to degrees: */
lon *= 180. / PI;
while( lon > 45.)
lon -= 90.;
while( lon < -45.)
lon += 90.;
jd -= lon * 365.25 / 360.;
err = lon;
}
return( jd);
}
#ifdef TEST_CODE
int main( const int argc, const char **argv)
{
double year = atof( argv[1]), jd = 1721139.29189 + 365.242137 * year;
double max_jd = 1721139.29189 + 365.242137 * 10000.;
/* jd is approx March equinox */
int season = 0, i, verbose = 0, output_mask = 15;
int use_ut = 0;
FILE *output_file = NULL;
for( i = 1; i < argc; i++)
if( argv[i][0] == '-')
switch( argv[i][1])
{
case 'u':
use_ut = 1;
break;
case 'm':
max_jd = 1721139.29189 + 365.242137 * atof( argv[i] + 2);
break;
case 'v':
verbose = 1 + atoi( argv[i] + 2);
break;
case 'o':
output_mask = atoi( argv[i] + 2);
break;
case 'f':
output_file = fopen( argv[i] + 2, "w");
break;
default:
printf( "'%s' is not a recognized option\n", argv[i]);
break;
}
setvbuf( stdout, NULL, _IONBF, 0);
if( verbose > 1)
printf( "Starting up...\n");
while( jd < max_jd)
{
char time_buff[80];
const char *season_text[4] =
{ "Mar equ", "Jun sol", "Sep equ", "Dec sol" };
if( verbose > 1)
printf( "Iterating...\n");
jd = get_solstice_equinox_date( jd);
if( !jd)
{
printf( "Couldn't find 'big_vsop.bin'\n");
exit( -1);
}
if( verbose > 2)
printf( " full_ctime\n");
if( use_ut)
jd -= td_minus_ut( jd) / 86400.;
full_ctime( time_buff, jd, 0);
if( (output_mask >> season) & 1)
{
if( output_file)
fprintf( output_file, "%s: %s %.5lf\n", season_text[season], time_buff, jd);
printf( "%s: %s %.5lf\n", season_text[season], time_buff, jd);
}
season = (season + 1) % 4;
jd += 91.3; /* advance to "mean" next season */
}
if( output_file)
fclose( output_file);
return( 0);
}
#endif
|
