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Diffstat (limited to 'ast/pal/palEcmat.c')
-rw-r--r-- | ast/pal/palEcmat.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/ast/pal/palEcmat.c b/ast/pal/palEcmat.c new file mode 100644 index 0000000..e9d9aeb --- /dev/null +++ b/ast/pal/palEcmat.c @@ -0,0 +1,82 @@ +/* +*+ +* Name: +* palEcmat + +* Purpose: +* Form the equatorial to ecliptic rotation matrix - IAU 2006 +* precession model. + +* Language: +* Starlink ANSI C + +* Type of Module: +* Library routine + +* Invocation: +* palEcmat( double date, double rmat[3][3] ) + +* Arguments: +* date = double (Given) +* TT as Modified Julian Date (JD-2400000.5). The difference +* between TT and TDB is of the order of a millisecond or two +* (i.e. about 0.02 arc-seconds). +* rmat = double[3][3] (Returned) +* Rotation matrix + +* Description: +* The equatorial to ecliptic rotation matrix is found and returned. +* The matrix is in the sense V(ecl) = RMAT * V(equ); the +* equator, equinox and ecliptic are mean of date. + +* Authors: +* PTW: Pat Wallace (STFC) +* DSB: David Berry (JAC, Hawaii) +* {enter_new_authors_here} + +* History: +* 2012-02-10 (DSB): +* Initial version with documentation taken from Fortran SLA +* Adapted with permission from the Fortran SLALIB library. +* {enter_further_changes_here} + +* Copyright: +* Copyright (C) 1996 Rutherford Appleton Laboratory +* Copyright (C) 2012 Science and Technology Facilities Council. +* All Rights Reserved. + +* Licence: +* This program is free software: you can redistribute it and/or +* modify it under the terms of the GNU Lesser General Public +* License as published by the Free Software Foundation, either +* version 3 of the License, or (at your option) any later +* version. +* +* This program is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +* GNU Lesser General Public License for more details. +* +* You should have received a copy of the GNU Lesser General +* License along with this program. If not, see +* <http://www.gnu.org/licenses/>. + +* Bugs: +* {note_any_bugs_here} +*- +*/ + +#include "pal.h" +#include "palmac.h" +#include "pal1sofa.h" + +void palEcmat( double date, double rmat[3][3] ) { + +/* Mean obliquity (the angle between the ecliptic and mean equator of + date). */ + double eps0 = eraObl06( PAL__MJD0, date ); + +/* Matrix */ + palDeuler( "X", eps0, 0.0, 0.0, rmat ); + +} |