src/gen/sun.c

#ifndef lint
static const char       RCSid[] = "$Id: sun.c,v 2.3 2003/02/22 02:07:24 greg Exp $";
#endif
/*
 *           SOLAR CALCULATIONS
 *
 *               3/31/87
 *
 */

#include  <math.h>

#define  PI  3.141592654

double  s_latitude = 0.66;      /* site latitude (radians) */
double  s_longitude = 2.13;     /* site longitude (radians) */
double  s_meridian = 2.0944;    /* standard meridian (radians) */


int
jdate(          /* Julian date (days into year) */
        int month,
        int day
)
{
        static short  mo_da[12] = {0,31,59,90,120,151,181,212,243,273,304,334};
        
        return(mo_da[month-1] + day);
}


double
stadj(          /* solar time adjustment from Julian date */
        int  jd
)
{
        return( 0.170 * sin( (4*PI/373) * (jd - 80) ) -
                0.129 * sin( (2*PI/355) * (jd - 8) ) +
                12 * (s_meridian - s_longitude) / PI );
}


double
sdec(           /* solar declination angle from Julian date */
        int  jd
)
{
        return( 0.4093 * sin( (2*PI/368) * (jd - 81) ) );
}


double
salt(   /* solar altitude from solar declination and solar time */
        double sd,
        double st
)
{
        return( asin( sin(s_latitude) * sin(sd) -
                        cos(s_latitude) * cos(sd) * cos(st*(PI/12)) ) );
}


double
sazi(   /* solar azimuth from solar declination and solar time */
        double sd,
        double st
)
{
        return( -atan2( cos(sd)*sin(st*(PI/12)),
                        -cos(s_latitude)*sin(sd) -
                        sin(s_latitude)*cos(sd)*cos(st*(PI/12)) ) );
}
Revision:	2.4
Committed:	Sun Nov 16 10:29:38 2003 UTC (20 years, 5 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad3R7P2, rad3R7P1, rad3R6, rad3R6P1, rad3R8, rad3R9
Changes since 2.3:	+19 -11 lines
Log Message:	Continued ANSIfication and reduced other compile warnings.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	schorsch	2.4	static const char RCSid[] = "$Id: sun.c,v 2.3 2003/02/22 02:07:24 greg Exp $";
3	greg	1.1	#endif
4	greg	1.2	/*
5	greg	1.1	* SOLAR CALCULATIONS
6			*
7			* 3/31/87
8			*
9			*/
10
11	greg	2.2	#include <math.h>
12
13	greg	1.1	#define PI 3.141592654
14
15			double s_latitude = 0.66; /* site latitude (radians) */
16			double s_longitude = 2.13; /* site longitude (radians) */
17			double s_meridian = 2.0944; /* standard meridian (radians) */
18
19
20			int
21	schorsch	2.4	jdate( /* Julian date (days into year) */
22			int month,
23			int day
24			)
25	greg	1.1	{
26			static short mo_da[12] = {0,31,59,90,120,151,181,212,243,273,304,334};
27
28			return(mo_da[month-1] + day);
29			}
30
31
32			double
33	schorsch	2.4	stadj( /* solar time adjustment from Julian date */
34			int jd
35			)
36	greg	1.1	{
37			return( 0.170 * sin( (4PI/373) (jd - 80) ) -
38			0.129 * sin( (2PI/355) (jd - 8) ) +
39			12 * (s_meridian - s_longitude) / PI );
40			}
41
42
43			double
44	schorsch	2.4	sdec( /* solar declination angle from Julian date */
45			int jd
46			)
47	greg	1.1	{
48			return( 0.4093 * sin( (2PI/368) (jd - 81) ) );
49			}
50
51
52			double
53	schorsch	2.4	salt( /* solar altitude from solar declination and solar time */
54			double sd,
55			double st
56			)
57	greg	1.1	{
58			return( asin( sin(s_latitude) * sin(sd) -
59			cos(s_latitude) * cos(sd) * cos(st*(PI/12)) ) );
60			}
61
62
63			double
64	schorsch	2.4	sazi( /* solar azimuth from solar declination and solar time */
65			double sd,
66			double st
67			)
68	greg	1.1	{
69			return( -atan2( cos(sd)sin(st(PI/12)),
70			-cos(s_latitude)*sin(sd) -
71			sin(s_latitude)cos(sd)cos(st*(PI/12)) ) );
72			}