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
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
|
/* standalone moon phase calculation */
/* clang -lm moon.c -o moon && ./moon */
/* via http://wiki.xxiivv.com/etc/moon.c.txt */
#include <stdio.h>
#include <math.h>
#include <time.h>
#define PI 3.1415926535897932384626433832795
#define RAD (PI / 180.0)
#define SMALL_FLOAT (1e-12)
typedef struct {
int year, month, day;
double hour;
} TimePlace;
void
JulianToDate(TimePlace *now, double jd)
{
long jdi, b, c, d, e, g, g1;
jd += 0.5;
jdi = jd;
if(jdi > 2299160) {
long a = (jdi - 1867216.25) / 36524.25;
b = jdi + 1 + a - a / 4;
} else
b = jdi;
c = b + 1524;
d = (c - 122.1) / 365.25;
e = 365.25 * d;
g = (c - e) / 30.6001;
g1 = 30.6001 * g;
now->day = c - e - g1;
now->hour = (jd - jdi) * 24.0;
if(g <= 13)
now->month = g - 1;
else
now->month = g - 13;
if(now->month > 2)
now->year = d - 4716;
else
now->year = d - 4715;
}
double
Julian(int year, int month, double day)
{
/* Returns the number of julian days for the specified day. */
int a, b = 0, c, e;
if(month < 3) {
year--;
month += 12;
}
if(year > 1582 || (year == 1582 && month > 10) ||
(year == 1582 && month == 10 && day > 15)) {
a = year / 100;
b = 2 - a + a / 4;
}
c = 365.25 * year;
e = 30.6001 * (month + 1);
return b + c + e + day + 1720994.5;
}
double
sun_position(double j)
{
double n, x, e, l, dl, v, m2;
int i;
n = 360 / 365.2422 * j;
i = n / 360;
n = n - i * 360.0;
x = n - 3.762863;
if(x < 0) x += 360;
x *= RAD;
e = x;
do {
dl = e - .016718 * sin(e) - x;
e = e - dl / (1 - .016718 * cos(e));
} while(fabs(dl) >= SMALL_FLOAT);
v = 360 / PI * atan(1.01686011182 * tan(e / 2));
l = v + 282.596403;
i = l / 360;
l = l - i * 360.0;
return l;
}
double
moon_position(double j, double ls)
{
double ms, l, mm, n, ev, sms, z, x, lm, bm, ae, ec, d, ds, as, dm;
int i;
/* ls = sun_position(j) */
ms = 0.985647332099 * j - 3.762863;
if(ms < 0) ms += 360.0;
l = 13.176396 * j + 64.975464;
i = l / 360;
l = l - i * 360.0;
if(l < 0) l += 360.0;
mm = l - 0.1114041 * j - 349.383063;
i = mm / 360;
mm -= i * 360.0;
n = 151.950429 - 0.0529539 * j;
i = n / 360;
n -= i * 360.0;
ev = 1.2739 * sin((2 * (l - ls) - mm) * RAD);
sms = sin(ms * RAD);
ae = 0.1858 * sms;
mm += ev - ae - 0.37 * sms;
ec = 6.2886 * sin(mm * RAD);
l += ev + ec - ae + 0.214 * sin(2 * mm * RAD);
l = 0.6583 * sin(2 * (l - ls) * RAD) + l;
return l;
}
double
moon_phase(int year, int month, int day, double hour, int *ip)
{
double j = Julian(year, month, (double)day + hour / 24.0) - 2444238.5;
double ls = sun_position(j);
double lm = moon_position(j, ls);
double t = lm - ls;
if(t < 0) t += 360;
*ip = (int)((t + 22.5) / 45) & 0x7;
return (1.0 - cos((lm - ls) * RAD)) / 2;
}
static void
nextDay(int *y, int *m, int *d, double dd)
{
TimePlace tp;
double jd = Julian(*y, *m, (double)*d);
jd += dd;
JulianToDate(&tp, jd);
*y = tp.year;
*m = tp.month;
*d = tp.day;
}
int
main(int argc, char **argv)
{
int y, m, d, m0, h, i;
int ymax, mmax, dmax, hmax;
int ymin, mmin, dmin, hmin;
int begun = 0;
double step = 1;
double pmax = 0;
double pmin = 1;
double plast = 0;
time_t seconds = time(NULL);
struct tm zt = {0};
struct tm *t = localtime(&seconds);
if(t == NULL)
t = &zt;
printf("year[%d]: ", t->tm_year + 1900);
fflush(stdout);
scanf("%d", &y);
printf("month[%d]: ", t->tm_mon + 1);
fflush(stdout);
scanf("%d", &m);
d = 1;
m0 = m;
printf("\nDate Time Phase Segment\n");
for(;;) {
double p;
int ip;
for(h = 0; h < 24; h += step) {
p = moon_phase(y, m, d, h, &ip);
if(begun) {
if(p > plast && p > pmax) {
pmax = p;
ymax = y;
mmax = m;
dmax = d;
hmax = h;
} else if(pmax) {
printf("%04d/%02d/%02d %02d:00 (fullest)\n",
ymax,
mmax,
dmax,
hmax);
pmax = 0;
}
if(p < plast && p < pmin) {
pmin = p;
ymin = y;
mmin = m;
dmin = d;
hmin = h;
} else if(pmin < 1) {
printf("%04d/%02d/%02d %02d:00 (newest)\n",
ymin,
mmin,
dmin,
hmin);
pmin = 1.0;
}
if(h == 16) {
printf("%04d/%02d/%02d %02d:00 %5.1f%% (%d)\n",
y,
m,
d,
h,
floor(p * 1000 + 0.5) / 10,
ip);
}
} else
begun = 1;
plast = p;
}
nextDay(&y, &m, &d, 1.0);
if(m != m0) break;
}
return 0;
}
|