#include "sofam.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 ** 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: 2008 May 11 ** ** Copyright (C) 2008 IAU SOFA Review 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) 2008 ** Standards Of Fundamental Astronomy Review Board ** of the International Astronomical Union. ** ** ===================== ** SOFA Software License ** ===================== ** ** NOTICE TO USER: ** ** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING TERMS AND CONDITIONS ** WHICH APPLY TO ITS USE. ** ** 1. The Software is owned by the IAU SOFA Review Board ("the Board"). ** ** 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 adapt the SOFA software and its ** algorithms for your own purposes and you may copy and distribute ** a resulting "derived work" to others on a world-wide, royalty-free ** basis, provided that the derived work complies 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 contain ** software provided by SOFA or software that has been distributed ** by or endorsed by SOFA. ** ** b) The source code of your derived work must contain descriptions ** of how the derived work is based upon and/or differs from the ** original SOFA software. ** ** c) The name(s) of all routine(s) that you distribute shall differ ** from the SOFA names, even when the SOFA content has not been ** otherwise changed. ** ** d) The routine-naming prefix "iau" shall not be used. ** ** e) 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. ** ** f) 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. ** ** 4. In any published work or commercial products which includes ** results achieved by using the SOFA software, you shall acknowledge ** that the SOFA software was used in obtaining those results. ** ** 5. You shall not cause the SOFA software to be brought into ** disrepute, either by misuse, or use for inappropriate tasks, or by ** inappropriate modification. ** ** 6. The SOFA software is provided "as is" and the Board makes no ** warranty as to its use or performance. The Board does not and ** cannot warrant the performance or results which the user may obtain ** by using the SOFA software. The Board 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 the Board be liable to the user for any consequential, ** incidental, or special damages, including any lost profits or lost ** savings, even if a Board representative has been advised of such ** damages, or for any claim by any third party. ** ** 7. 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. ** ** Correspondence concerning SOFA software should be addressed as ** follows: ** ** Internet email: sofa@rl.ac.uk ** Postal address: IAU SOFA Center ** Rutherford Appleton Laboratory ** Chilton, Didcot, Oxon OX11 0QX ** United Kingdom ** **---------------------------------------------------------------------*/ }