#include "sofa.h" void iauC2teqx(double rbpn[3][3], double gst, double rpom[3][3], double rc2t[3][3]) /* ** - - - - - - - - - - ** i a u C 2 t e q x ** - - - - - - - - - - ** ** Assemble the celestial to terrestrial matrix from equinox-based ** components (the celestial-to-true matrix, the Greenwich Apparent ** Sidereal Time and the polar motion matrix). ** ** This function is part of the International Astronomical Union's ** SOFA (Standards Of Fundamental Astronomy) software collection. ** ** Status: support function. ** ** Given: ** rbpn double[3][3] celestial-to-true matrix ** gst double Greenwich (apparent) Sidereal Time (radians) ** rpom double[3][3] polar-motion matrix ** ** Returned: ** rc2t double[3][3] celestial-to-terrestrial matrix (Note 2) ** ** Notes: ** ** 1) This function constructs the rotation matrix that transforms ** vectors in the celestial system into vectors in the terrestrial ** system. It does so starting from precomputed components, namely ** the matrix which rotates from celestial coordinates to the ** true equator and equinox of date, the Greenwich Apparent Sidereal ** Time and the polar motion matrix. One use of the present function ** is when generating a series of celestial-to-terrestrial matrices ** where only the Sidereal Time changes, avoiding the considerable ** overhead of recomputing the precession-nutation more often than ** necessary to achieve given accuracy objectives. ** ** 2) The relationship between the arguments is as follows: ** ** [TRS] = rpom * R_3(gst) * rbpn * [CRS] ** ** = rc2t * [CRS] ** ** where [CRS] is a vector in the Geocentric Celestial Reference ** System and [TRS] is a vector in the International Terrestrial ** Reference System (see IERS Conventions 2003). ** ** Called: ** iauCr copy r-matrix ** iauRz rotate around Z-axis ** iauRxr product of two r-matrices ** ** Reference: ** ** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), ** IERS Technical Note No. 32, BKG (2004) ** ** This revision: 2013 August 24 ** ** SOFA release 2013-12-02 ** ** Copyright (C) 2013 IAU SOFA Board. See notes at end. */ { double r[3][3]; /* Construct the matrix. */ iauCr(rbpn, r); iauRz(gst, r); iauRxr(rpom, r, rc2t); return; /*---------------------------------------------------------------------- ** ** Copyright (C) 2013 ** Standards Of Fundamental Astronomy Board ** of the International Astronomical Union. ** ** ===================== ** SOFA Software License ** ===================== ** ** NOTICE TO USER: ** ** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND ** CONDITIONS WHICH APPLY TO ITS USE. ** ** 1. The Software is owned by the IAU SOFA Board ("SOFA"). ** ** 2. Permission is granted to anyone to use the SOFA software for any ** purpose, including commercial applications, free of charge and ** without payment of royalties, subject to the conditions and ** restrictions listed below. ** ** 3. You (the user) may copy and distribute SOFA source code to others, ** and use and adapt its code and algorithms in your own software, ** on a world-wide, royalty-free basis. That portion of your ** distribution that does not consist of intact and unchanged copies ** of SOFA source code files is a "derived work" that must comply ** with the following requirements: ** ** a) Your work shall be marked or carry a statement that it ** (i) uses routines and computations derived by you from ** software provided by SOFA under license to you; and ** (ii) does not itself constitute software provided by and/or ** endorsed by SOFA. ** ** b) The source code of your derived work must contain descriptions ** of how the derived work is based upon, contains and/or differs ** from the original SOFA software. ** ** c) The names of all routines in your derived work shall not ** include the prefix "iau" or "sofa" or trivial modifications ** thereof such as changes of case. ** ** d) The origin of the SOFA components of your derived work must ** not be misrepresented; you must not claim that you wrote the ** original software, nor file a patent application for SOFA ** software or algorithms embedded in the SOFA software. ** ** e) These requirements must be reproduced intact in any source ** distribution and shall apply to anyone to whom you have ** granted a further right to modify the source code of your ** derived work. ** ** Note that, as originally distributed, the SOFA software is ** intended to be a definitive implementation of the IAU standards, ** and consequently third-party modifications are discouraged. All ** variations, no matter how minor, must be explicitly marked as ** such, as explained above. ** ** 4. You shall not cause the SOFA software to be brought into ** disrepute, either by misuse, or use for inappropriate tasks, or ** by inappropriate modification. ** ** 5. The SOFA software is provided "as is" and SOFA makes no warranty ** as to its use or performance. SOFA does not and cannot warrant ** the performance or results which the user may obtain by using the ** SOFA software. SOFA makes no warranties, express or implied, as ** to non-infringement of third party rights, merchantability, or ** fitness for any particular purpose. In no event will SOFA be ** liable to the user for any consequential, incidental, or special ** damages, including any lost profits or lost savings, even if a ** SOFA representative has been advised of such damages, or for any ** claim by any third party. ** ** 6. The provision of any version of the SOFA software under the terms ** and conditions specified herein does not imply that future ** versions will also be made available under the same terms and ** conditions. * ** In any published work or commercial product which uses the SOFA ** software directly, acknowledgement (see www.iausofa.org) is ** appreciated. ** ** Correspondence concerning SOFA software should be addressed as ** follows: ** ** By email: sofa@ukho.gov.uk ** By post: IAU SOFA Center ** HM Nautical Almanac Office ** UK Hydrographic Office ** Admiralty Way, Taunton ** Somerset, TA1 2DN ** United Kingdom ** **--------------------------------------------------------------------*/ }