summaryrefslogtreecommitdiff
path: root/navit/sunriset.h
blob: 36a770935c74fae5d63c1095f076ff8ccc28968a (plain)
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
extern const char* timezone_name;
extern long int timezone_offset;

#define TMOD(x) ((x)<0?(x)+24:((x)>=24?(x)-24:(x)))
#define DAYSOFF(x) ((x)<0?"(-1) ":((x)>=24?"(+1) ":""))

#define HOURS(h) ((int)(floor(h)))
#define MINUTES(h) ((int)(60*(h-floor(h))))

#ifndef ABS
#define ABS(x) ((x)<0?-(x):(x)) 
#endif

/* A macro to compute the number of days elapsed since 2000 Jan 0.0 */
/* (which is equal to 1999 Dec 31, 0h UT)                           */
/* Dan R sez: This is some pretty fucking high magic. */
#define days_since_2000_Jan_0(y,m,d) \
    (367L*(y)-((7*((y)+(((m)+9)/12)))/4)+((275*(m))/9)+(d)-730530L)

/* Some conversion factors between radians and degrees */

#ifndef PI
 #define PI        3.1415926535897932384
#endif

#define RADEG     ( 180.0 / PI )
#define DEGRAD    ( PI / 180.0 )

/* The trigonometric functions in degrees */

#define sind(x)  sin((x)*DEGRAD)
#define cosd(x)  cos((x)*DEGRAD)
#define tand(x)  tan((x)*DEGRAD)

#define atand(x)    (RADEG*atan(x))
#define asind(x)    (RADEG*asin(x))
#define acosd(x)    (RADEG*acos(x))
#define atan2d(y,x) (RADEG*atan2(y,x))

/* Following are some macros around the "workhorse" function __daylen__ */
/* They mainly fill in the desired values for the reference altitude    */
/* below the horizon, and also selects whether this altitude should     */
/* refer to the Sun's center or its upper limb.                         */


/* This macro computes the length of the day, from sunrise to sunset. */
/* Sunrise/set is considered to occur when the Sun's upper limb is    */
/* 50 arc minutes below the horizon (this accounts for the refraction */
/* of the Earth's atmosphere).                                        */
/* The original version of the program used the value of 35 arc mins, */
/* which is the accepted value in Sweden.                             */
#define day_length(year,month,day,lon,lat)  \
        __daylen__( year, month, day, lon, lat, -50.0/60.0, 1 )

/* This macro computes the length of the day, including civil twilight. */
/* Civil twilight starts/ends when the Sun's center is 6 degrees below  */
/* the horizon.                                                         */
#define day_civil_twilight_length(year,month,day,lon,lat)  \
        __daylen__( year, month, day, lon, lat, -6.0, 0 )

/* This macro computes the length of the day, incl. nautical twilight.  */
/* Nautical twilight starts/ends when the Sun's center is 12 degrees    */
/* below the horizon.                                                   */
#define day_nautical_twilight_length(year,month,day,lon,lat)  \
        __daylen__( year, month, day, lon, lat, -12.0, 0 )

/* This macro computes the length of the day, incl. astronomical twilight. */
/* Astronomical twilight starts/ends when the Sun's center is 18 degrees   */
/* below the horizon.                                                      */
#define day_astronomical_twilight_length(year,month,day,lon,lat)  \
        __daylen__( year, month, day, lon, lat, -18.0, 0 )


/* This macro computes times for sunrise/sunset.                      */
/* Sunrise/set is considered to occur when the Sun's upper limb is    */
/* 35 arc minutes below the horizon (this accounts for the refraction */
/* of the Earth's atmosphere).                                        */
#define sun_rise_set(year,month,day,lon,lat,rise,set)  \
        __sunriset__( year, month, day, lon, lat, -35.0/60.0, 1, rise, set )

/* This macro computes the start and end times of civil twilight.       */
/* Civil twilight starts/ends when the Sun's center is 6 degrees below  */
/* the horizon.                                                         */
#define civil_twilight(year,month,day,lon,lat,start,end)  \
        __sunriset__( year, month, day, lon, lat, -6.0, 0, start, end )

/* This macro computes the start and end times of nautical twilight.    */
/* Nautical twilight starts/ends when the Sun's center is 12 degrees    */
/* below the horizon.                                                   */
#define nautical_twilight(year,month,day,lon,lat,start,end)  \
        __sunriset__( year, month, day, lon, lat, -12.0, 0, start, end )

/* This macro computes the start and end times of astronomical twilight.   */
/* Astronomical twilight starts/ends when the Sun's center is 18 degrees   */
/* below the horizon.                                                      */
#define astronomical_twilight(year,month,day,lon,lat,start,end)  \
        __sunriset__( year, month, day, lon, lat, -18.0, 0, start, end )


/* Function prototypes */

double __daylen__( int year, int month, int day, double lon, double lat,
                   double altit, int upper_limb );

int __sunriset__( int year, int month, int day, double lon, double lat,
                  double altit, int upper_limb, double *rise, double *set );

void sunpos( double d, double *lon, double *r );

void sun_RA_dec( double d, double *RA, double *dec, double *r );

double revolution( double x );

double rev180( double x );

double GMST0( double d );