source: trunk/MagicSoft/slalib/nut.c@ 9472

Last change on this file since 9472 was 731, checked in by tbretz, 24 years ago
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1#include "slalib.h"
2#include "slamac.h"
3void slaNut ( double date, double rmatn[3][3] )
4/*
5** - - - - - - -
6** s l a N u t
7** - - - - - - -
8**
9** Form the matrix of nutation for a given date (IAU 1980 theory).
10**
11** (double precision)
12**
13** References:
14** Final report of the IAU working group on nutation,
15** chairman P.K.Seidelmann, 1980.
16** Kaplan, G.H., 1981, USNO circular no. 163, pA3-6.
17**
18** Given:
19** date double TDB (loosely ET) as Modified Julian Date
20** (=JD-2400000.5)
21**
22** Returned:
23** rmatn double[3][3] nutation matrix
24**
25** The matrix is in the sense v(true) = rmatn * v(mean) .
26**
27** Called: slaNutc, slaDeuler
28**
29** Last revision: 11 April 1999
30**
31** Copyright P.T.Wallace. All rights reserved.
32*/
33{
34 double dpsi, deps, eps0;
35
36/* Nutation components and mean obliquity */
37 slaNutc ( date, &dpsi, &deps, &eps0 );
38
39/* Rotation matrix */
40 slaDeuler ( "xzx", eps0, -dpsi, - ( eps0 + deps ), rmatn );
41}
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