source: trunk/FACT++/pal/palEcleq.c@ 19353

Last change on this file since 19353 was 18347, checked in by tbretz, 9 years ago
File size: 2.7 KB
Line 
1/*
2*+
3* Name:
4* palEcleq
5
6* Purpose:
7* Transform from ecliptic coordinates to J2000.0 equatorial coordinates
8
9* Language:
10* Starlink ANSI C
11
12* Type of Module:
13* Library routine
14
15* Invocation:
16* void palEcleq ( double dl, double db, double date,
17* double *dr, double *dd );
18
19* Arguments:
20* dl = double (Given)
21* Ecliptic longitude (mean of date, IAU 1980 theory, radians)
22* db = double (Given)
23* Ecliptic latitude (mean of date, IAU 1980 theory, radians)
24* date = double (Given)
25* TT as Modified Julian Date (JD-2400000.5). The difference
26* between TT and TDB is of the order of a millisecond or two
27* (i.e. about 0.02 arc-seconds).
28* dr = double * (Returned)
29* J2000.0 mean RA (radians)
30* dd = double * (Returned)
31* J2000.0 mean Dec (Radians)
32
33* Description:
34* Transform from ecliptic coordinate to J2000.0 equatorial coordinates.
35
36* Authors:
37* PTW: Patrick T. Wallace
38* TIMJ: Tim Jenness (Cornell University)
39* {enter_new_authors_here}
40
41* History:
42* 2014-11-18 (TIMJ):
43* Initial version
44* Adapted with permission from the Fortran SLALIB library.
45* {enter_further_changes_here}
46
47* Copyright:
48* Copyright (C) 1995 Rutherford Appleton Laboratory
49* Copyright (C) 2014 Cornell University
50* All Rights Reserved.
51
52* Licence:
53* This program is free software; you can redistribute it and/or
54* modify it under the terms of the GNU General Public License as
55* published by the Free Software Foundation; either version 3 of
56* the License, or (at your option) any later version.
57*
58* This program is distributed in the hope that it will be
59* useful, but WITHOUT ANY WARRANTY; without even the implied
60* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
61* PURPOSE. See the GNU General Public License for more details.
62*
63* You should have received a copy of the GNU General Public License
64* along with this program; if not, write to the Free Software
65* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
66* MA 02110-1301, USA.
67
68* Bugs:
69* {note_any_bugs_here}
70*-
71*/
72
73#include "pal.h"
74#include "pal1sofa.h"
75
76void palEcleq ( double dl, double db, double date, double *dr, double *dd ) {
77 double v1[3], v2[3];
78 double rmat[3][3];
79
80 /* Spherical to Cartesian */
81 eraS2c( dl, db, v1 );
82
83 /* Ecliptic to equatorial */
84 palEcmat( date, rmat );
85 eraTrxp( rmat, v1, v2 );
86
87 /* Mean of date to J2000 */
88 palPrec( 2000.0, palEpj(date), rmat );
89 eraTrxp( rmat, v2, v1 );
90
91 /* Cartesian to spherical */
92 eraC2s( v1, dr, dd );
93
94 /* Express in conventional range */
95 *dr = eraAnp( *dr );
96 *dd = palDrange( *dd );
97}
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