| 1 | #include "slalib.h"
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| 2 | #include "slamac.h"
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| 3 | void slaEcleq ( double dl, double db, double date,
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| 4 | double *dr, double *dd)
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| 5 | /*
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| 6 | ** - - - - - - - - -
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| 7 | ** s l a E c l e q
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| 8 | ** - - - - - - - - -
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| 9 | **
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| 10 | ** Transformation from ecliptic coordinates to J2000.0
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| 11 | ** equatorial coordinates.
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| 12 | **
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| 13 | ** (double precision)
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| 14 | **
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| 15 | ** Given:
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| 16 | ** dl,db double ecliptic longitude and latitude
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| 17 | ** (mean of date, IAU 1980 theory, radians)
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| 18 | ** date double TDB (loosely ET) as Modified Julian Date
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| 19 | ** (JD-2400000.5)
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| 20 | ** Returned:
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| 21 | ** *dr,*dd double J2000.0 mean RA,Dec (radians)
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| 22 | **
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| 23 | ** Called:
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| 24 | ** slaDcs2c, slaEcmat, slaDimxv, slaPrec, slaEpj, slaDcc2s,
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| 25 | ** slaDranrm, slaDrange
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| 26 | **
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| 27 | ** Last revision: 31 October 1993
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| 28 | **
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| 29 | ** Copyright P.T.Wallace. All rights reserved.
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| 30 | */
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| 31 | {
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| 32 | double rmat[3][3], v1[3], v2[3];
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| 33 |
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| 34 | /* Spherical to Cartesian */
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| 35 | slaDcs2c ( dl, db, v1 );
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| 36 |
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| 37 | /* Ecliptic to equatorial */
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| 38 | slaEcmat ( date, rmat );
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| 39 | slaDimxv ( rmat, v1, v2 );
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| 40 |
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| 41 | /* Mean of date to J2000 */
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| 42 | slaPrec ( 2000.0, slaEpj ( date ), rmat );
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| 43 | slaDimxv ( rmat, v2, v1 );
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| 44 |
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| 45 | /* Cartesian to spherical */
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| 46 | slaDcc2s ( v1, dr, dd );
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| 47 |
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| 48 | /* Express in conventional ranges */
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| 49 | *dr = slaDranrm ( *dr );
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| 50 | *dd = slaDrange ( *dd );
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| 51 | }
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