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greg |
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/* Copyright (c) 1989 Regents of the University of California */ |
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greg |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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greg |
1.2 |
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/* |
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greg |
1.1 |
* SOLAR CALCULATIONS |
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* |
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* 3/31/87 |
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* |
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*/ |
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#define PI 3.141592654 |
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double s_latitude = 0.66; /* site latitude (radians) */ |
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double s_longitude = 2.13; /* site longitude (radians) */ |
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double s_meridian = 2.0944; /* standard meridian (radians) */ |
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int |
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jdate(month, day) /* Julian date (days into year) */ |
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int month, day; |
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{ |
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static short mo_da[12] = {0,31,59,90,120,151,181,212,243,273,304,334}; |
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return(mo_da[month-1] + day); |
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} |
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double |
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stadj(jd) /* solar time adjustment from Julian date */ |
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int jd; |
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{ |
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double sin(); |
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return( 0.170 * sin( (4*PI/373) * (jd - 80) ) - |
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0.129 * sin( (2*PI/355) * (jd - 8) ) + |
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12 * (s_meridian - s_longitude) / PI ); |
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} |
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double |
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sdec(jd) /* solar declination angle from Julian date */ |
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int jd; |
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{ |
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double sin(); |
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return( 0.4093 * sin( (2*PI/368) * (jd - 81) ) ); |
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} |
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double |
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salt(sd, st) /* solar altitude from solar declination and solar time */ |
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double sd, st; |
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{ |
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double sin(), cos(), asin(); |
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return( asin( sin(s_latitude) * sin(sd) - |
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cos(s_latitude) * cos(sd) * cos(st*(PI/12)) ) ); |
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} |
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double |
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sazi(sd, st) /* solar azimuth from solar declination and solar time */ |
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double sd, st; |
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{ |
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double sin(), cos(), atan2(); |
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return( -atan2( cos(sd)*sin(st*(PI/12)), |
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-cos(s_latitude)*sin(sd) - |
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sin(s_latitude)*cos(sd)*cos(st*(PI/12)) ) ); |
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} |
