| 1 | /*
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| 2 | *+
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| 3 | * Name:
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| 4 | * palNut
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| 5 |
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| 6 | * Purpose:
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| 7 | * Form the matrix of nutation
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| 8 |
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| 9 | * Language:
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| 10 | * Starlink ANSI C
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| 11 |
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| 12 | * Type of Module:
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| 13 | * Library routine
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| 14 |
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| 15 | * Invocation:
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| 16 | * void palNut( double date, double rmatn[3][3] );
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| 17 |
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| 18 | * Arguments:
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| 19 | * date = double (Given)
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| 20 | * TT as modified Julian date (JD-2400000.5)
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| 21 | * rmatn = double [3][3] (Returned)
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| 22 | * Nutation matrix in the sense v(true)=rmatn * v(mean)
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| 23 | * where v(true) is the star vector relative to the
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| 24 | * true equator and equinox of date and v(mean) is the
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| 25 | * star vector relative to the mean equator and equinox
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| 26 | * of date.
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| 27 |
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| 28 | * Description:
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| 29 | * Form the matrix of nutation for a given date using
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| 30 | * the IAU 2006 nutation model and palDeuler.
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| 31 |
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| 32 | * Authors:
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| 33 | * PTW: Patrick T. Wallace
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| 34 | * TIMJ: Tim Jenness (JAC, Hawaii)
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| 35 | * {enter_new_authors_here}
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| 36 |
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| 37 | * Notes:
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| 38 | * - Uses eraNut06a via palNutc
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| 39 | * - The distinction between TDB and TT is negligible. For all but
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| 40 | * the most critical applications UTC is adequate.
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| 41 |
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| 42 | * History:
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| 43 | * 2012-03-07 (TIMJ):
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| 44 | * Initial version
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| 45 | * Adapted with permission from the Fortran SLALIB library.
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| 46 | * {enter_further_changes_here}
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| 47 |
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| 48 | * Copyright:
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| 49 | * Copyright (C) 2005 Patrick T. Wallace
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| 50 | * Copyright (C) 2012 Science and Technology Facilities Council.
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| 51 | * All Rights Reserved.
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| 52 |
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| 53 | * Licence:
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| 54 | * This program is free software; you can redistribute it and/or
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| 55 | * modify it under the terms of the GNU General Public License as
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| 56 | * published by the Free Software Foundation; either version 3 of
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| 57 | * the License, or (at your option) any later version.
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| 58 | *
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| 59 | * This program is distributed in the hope that it will be
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| 60 | * useful, but WITHOUT ANY WARRANTY; without even the implied
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| 61 | * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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| 62 | * PURPOSE. See the GNU General Public License for more details.
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| 63 | *
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| 64 | * You should have received a copy of the GNU General Public License
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| 65 | * along with this program; if not, write to the Free Software
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| 66 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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| 67 | * MA 02110-1301, USA.
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| 68 |
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| 69 | * Bugs:
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| 70 | * {note_any_bugs_here}
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| 71 | *-
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| 72 | */
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| 73 |
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| 74 | #include "pal.h"
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| 75 |
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| 76 | void palNut( double date, double rmatn[3][3]) {
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| 77 | double dpsi, deps, eps0;
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| 78 |
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| 79 | /* Nutation component and mean obliquity */
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| 80 | palNutc( date, &dpsi, &deps, &eps0 );
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| 81 |
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| 82 | /* Rotation matrix */
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| 83 | palDeuler( "XZX", eps0, -dpsi, -(eps0+deps), rmatn );
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| 84 |
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| 85 | }
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